SBI 189

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SINGLE FAMILY HOUSES

SBI

189

Insulation – moisture protection, acoustics, fire resistance, ventilation and strength.

2

nd

EDITION

SBI-DIRECTION 189

STATENS BVGGEFORSKNINGSINSTITUT

1999

Translation from Danish to English: Karsten Lundager and Roger Taylor

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Preface

This SBI Direction is complementary to Building Regulations for Small Dwelling, 1998 and replaces SBI Direction 147: Constructions in small house, which was complementary to Building Regulations for Small Dwelling, 1985. The Direction also replaces SBI Direction 111: Thermal insulation of buildings, 2nd edition.

The Direction covers such issues as thermal insulation, moisture insulation, sound insulation, fire, wet rooms, indoor climate as well as strength and stability.

As the Direction covers a wide range of subject matters is has been necessary to call upon a wide range of specialist SBI writers. Apart from the project manager, civil engineer Jørgen Munch-Andersen, the following have also participated:

Academy engineer Søren

Aggerholm, academy engineer Niels Christian Bergsøe, civil engineer Erik Brandt, academy engineer Mogens Buhelt, civil engineer Henry H. Knutsson, academy engineer Peter A. Nielsen and architect m.a.a. Hans Zacharias-sen. The extensive editing work has been carried out by civil engineer Jens Christian Ellum.

Several technicians within the Danish building industry have contributed with valuable information. We are very grateful for these contributions.

The elaboration of the Direction has received support from By- og Boligministeriel og Energistyrelsen. (Ministry of Housing)

The target group of this Direction is engineers, architects, contractors and other designers and executors within construction. Also public administration is a target group.

Supplements to the SBI Direction will be published at the SBF homepage http://www.sbi.dk.

SBI

STATENS

BYGGEFORSKNINGSINST

ITUT

Department of Building technique and Productivity, June 1998

Georg Christensen, Research

manager Preface to the 2nd edition This is the 2nd edition of SBI Direction 189 concerning »Single family houses«. Compared to the 1st edition a few changes and additions have been made. These are to large degree based on a dialogue with practice which has taken place during a number of seminars where the Direction has been presented. In relation to that SBI would like to express its gratitude for all received suggestions and comments for improvement.

SBI

STATENS

BYGGEFORSKNINGSINST

ITUT

Department of Building technique and Productivity, November 1998 Georg Christensen, Research manager

SBI Direction 189 9

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Introduction

This SBI Direction contains guidance on and examples of constructions in one family houses. The examples all comply with the requirements laid down in “Building Regulations for Small Dwellings, 1998 (BRS 98)

The Direction covers detached as well as semidetached one family houses up to 2 storeys and a basement, as shown in figure 1. The maximum height above ground level is 8.5 m, measured from the ridge.

It must be stressed that the examples shown in this Direction should be considered as examples, and alternative solutions fulfilling the requirements in BRS 98 are acceptable. An example: The dimensions stated for load bearing and bracing constructions may in many cases be reduced considering the actual conditions under which they are carried out. This, however, requires dimensioning by an engineer.

Reference to other existing literature is either done by full reference in the text (written in italics) or simply by referring to the list of literature at the back of the Direction (only in the Danish Version).

The Direction starts with a short introduction to the load-bearing and bracing system with special emphasis on load acceptance. In enclosure D, The Bracing System, it is shown how the bracing necessary to secure the stability of the house can be designed and dimensioned,. Different parts of the house are accounted for. Examples of building components are shown; their design and how they are connected to other building components. In the

out in a satisfactory way and at the same time fulfilling the requirements concerning fire resistance and sound insulation. In the shown examples it will in many cases be possible to substitute mineral wool with other insulation materials but care must be taken that the fire resistance requirements are met.

Dimensions are stated for usual constructions. Alternative constructions may be dimensioned using the loads stated in enclosure A, Loads.

The U-values in the shown examples fulfil the requirements of U-values stated in BRS 98, which are also the basis for determining the Heat Loss Frame for the house. In the chapter Heat Insulation it is discussed how the Heat Loss Frame and the Energy Frame could be used as a tool for choosing constructions with other U-values.

In the chapters Wet Rooms and Glass examples of fulfilment of BRS 98 requirements in the said areas are shown.

The chapter Indoor Climate primarily describes the establishment of satisfactory natural ventilation in one family houses. Issues related to stoking are treated in the chapter Fire Places and Chimneys.

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Side 7 af 101 Ground floor

1 storey with ground supported floor

Ground floor

Basement

1 storey with basement

Attic Attic

Ground floor

1½ storey with ground supported floor

Ground floor

Basement

1½ storey with basement

1st_floor

Ground floor

1st_floor

Ground floor

Basement 2 storeys with ground supported floor

2 storeys with basement

Figure 1. The Building Regulations for Small Dwellings encompasses one

family houses up to 2 storeys and a basement. The houses may be detached

or semidetached. The Regulations do not apply to houses with separate

dwellings divided by a storey partition (horizontal division).

SBI Direction 189 11

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Loads, load acceptance and

load transmission

Houses shall be built in such a way that they can accept and transmit occurring loads. The loads can be divided into:

• Gravity based loads, i.e. the dead load of building components, the

imposed load (furniture and people) and snow load.

• Wind action

Wind acts primarily perpendicularly on the surfaces of the house. The external walls and the roof surfaces at the windward side are exposed to pressure. The other surfaces are exposed to suction.

Usually, the acceptance and transmission of gravity-based load do not present major problems. However, one must be aware that load-bearing walls are affected by horizontal wind action and vertical load simultaneously. The acceptance and transmission of wind

action require a stabilising system, which is described briefly in the following.

Figure 2 shows the most important types of collapse, which must be prevented by the use of a stabilising system.

Terrain classes for wind

The force of the wind action depends among other things on the type of the terrain

surrounding the building. In The Code of practice for Loads for the design of structures (DS 410) three terrain classes are defined. In the Code these classes are referred to as

Smooth, Agricultural and Built- up, see table 1. Most new constructions shall be dimensioned for wind action according to the terrain class Agricultural

.

In an area with low buildings surrounded by farmland the wind action will only be reduced to a level corresponding to terrain class Smooth some 500-600 m inside the built-up area.

a) b)

c)

d) _e)

f)

Figure 2. The stability of the house is ensured by anchoring the various structural elements to each other. The roof trusses must be braced to prevent them from cascading (a) and anchored against horizontal forces (b) and upward-acting forces (c). The walls must be supported at the top by the ceiling diaphragm (d), and this must be able to transmit horizontal forces to the wind-bracing walls. In ome cases, the walls must also be anchored at the bottom to prevent sliding (e) and collapse or lifting (f)

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SBI Direction 189 KLJ

9 SBI-Direction 186: “Stability of small

houses” gives a more detailed description of terrain classes and of the possibilities to utilise the wind action’s dependency on the actual shelter conditions in connection to wind from various directions.

Table 1 Definition of terrain classes according to “Loads for the design of structures”. The description applies to the surrounding terrain. Terrain

class

Description of terrain

Smooth Smooth terrain e.g. aquatic areas and moors without shelter. Agricultural Farm land with wind breaks,

farms with gardens etc. Built-up Built-up areas or woodland.

Stabilising system

The central parts of the stabilising system are the bracing walls and the so-called ceiling diaphragm . Some important terms are indicated on figures 3 and 4.

The ceiling diaphragm supports the external walls at the top and furthermore transmits horizontal forces from the roof including the gable triangles. The ceiling diaphragm must be able to transmit these forces to the bracing walls, which may be internal walls as well as external walls. Consequently, the ceiling diaphragm must be fixed to all external walls and to the internal bracing walls. Further, the ceiling diaphragm must be sufficiently stiff in order to secure that forces can be distributed to the braced walls without causing fatal deformations, see figure 5.

The stabilising system must be able to transmit the forces to the foundation or floor slab. This will often require a protection against sliding and /or anchoring against upward-acting forces on the walls

In addition, the roof construction itself must be braced and anchored to prevent failure as shown in figures 2a-2c. Failure as shown in figure 2c is caused by the considerable lifting force occurring as a result of the longitudinal wind (along the roof).

Figure 3. Wind acting transversely: The gables and internal transverse wall may act as bracing walls.

Figure 4. Wind acting along the house: The facades and the internal longitudinal walls may act as bracing walls.

Figure 5. The ceiling diaphragm shall be adequately strong and rigid in order to distribute the wind action to the bracing walls. Transverse wall Gable Facade Transverse wind action Longitudinal wall Facade Longitudinal wind action Wind SBI Direction 189 13 Translation KLJ

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Dimensioning and design

The dimensioning of load bearing and stabilising structures usually requires the assistance of an engineer. Enclosures A and D can be used to assist when dimensioning. Enclosure A, Loads, gives loads used in dimensioning structural elements affected by vertical action perpendicularly to their plane.

The chapters concerning the specific construction elements give examples of designs with sufficient strength to transmit the forces.

Enclosure D, Stabilising system describes how the stabilising system in 1-and 1½ storey single length houses with pitched roof can be designed and dimensioned.

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SBI Direction 189,

KLJ 11

Foundations

Foundation includes dimensioning and construction of foundations i.e. the structural elements that transmit load from the house to firm bearing stratum. Examples of

foundations for various types of buildings are shown in figures 6,7 and 8.

Figure 6

Foundation at ground supported floor. Normally in situ cast concrete as a deep strip foundation is used (cross-hatched in the figure). The upper part is often built using clinker concrete blocks. Hollow concrete blocks may also be used especially where the topsoil excavation level is below the topside of the deep strip foundation, thus avoiding the use of formwork for casting the upper part of the foundation. The foundation shall have at least the same width as the wall above and should be symmetrically placed below this. The figure also shows the placement of a perimeter drain and a branch drain, which connect the capillary breaking layer beneath the floor with the perimeter drain. It is not necessary to connect the branch drain directly to the perimeter drain.

This chapter only applies to the construction elements accentuated in these figures. The remaining elements are discussed in subsequent chapters.

Figure 7

Foundation at crawl space. Often a concrete pad is cast in situ (cross-hatched in the figure) and the crawl space wall is then constructed using clinker concrete blocks or hollow concrete blocks cast with concrete. The wall can also be cast fully or partly in situ, i.e. to the topsoil excavation level. The foundation shall have at least the same width as the wall above, and it should be

symmetrically placed below this.

Level of topsoil excavation Level of topsoil

excavation Level of topsoil_excavation

Excavation trench profile

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Figure 8

Foundation at basement. Usually a concrete pad is cast in situ (cross-hatched in the figure) and the basement wall is then built using clinker concrete blocks or using hollow concrete blocks cast with concrete.

Alternatively, the entire wall can be cast in situ. The foundation pad shall have at least the same width as the basement wall and it should be symmetrically placed below it. The figure also shows the placement of a perimeter drain and a branch drain which connect the capillary breaking layer under the floor with the perimeter drain.

Foundation control classes

Foundation work must comply with the directions given in Foundation Engineering -DS 415 in which 3 foundation control classes are defined: Low, normal and high control class. In the present SBI direction, it is assumed that the control class is low. This class only comprises small and simple foundations on virgin and stable stratum above the water table. Such foundations can -under certain conditions (as mentioned in the following) - be constructed based on empiric knowledge and without prior geo-technical surveys. If these conditions are not fulfilled the foundation shall be constructed according to normal or high foundation control class. In such cases geo-technical surveys of the sub soil shall be undertaken. Likewise, design as well as implementation control shall be carried out by experts. In such cases, we refer to the more extensive treatment of foundation problems in SBI-Direction 181: “Foundation of smaller buildings”.

Low foundation control class

Foundations shall be constructed to a dept where they will rest directly on firm bearing stratum. That is usually a packed mixture of clay, sand and stone (called moraine clay by

Excavation trench profile

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SBI Direction 189,

KLJ 13

can also consist of packed sand, gravel or coarse silt (called non-cohesive soil).

If the bearing stratum is deeper than app. 2 m, it will usually be expedient to let an expert carry out the actual design work.

When inspecting finished excavations, it must always be verified that foundation is carried out on firm and stable sediments. This inspection must be carried out by a person who possesses adequate geological and geo-technical knowledge.

The local building authorities will in many cases demand to inspect the excavation before casting the first foundation. Likewise, the authorities may demand inspection of other parts of the construction.

Usually the following soil layers are not considered stable: Fill, soil which has been excavated before or frozen soil, sediments with content of organic material e.g. turf, mud and certain special fat clays. The latter is characterised by not containing sand or stones and by having a high water content (25-40%), and by the fact that they sometimes crack. Such very fat clays are found in the western part of Funen and in the eastern part of

Jutland .e.g. by the Little Belt, by the fjords in eastern Jutland and in the area around Skive.

Apart from resting on a bearing stratum, foundations shall be constructed at least to frost-free depth. Regarding external wall foundations, frost-free depth is usually 0.9 m below the surface. However, with special soil conditions such as silty soil the depth may have to be high. Silt is a soil type with grains rougher than clay but finer than sand.

In low foundation control class there must be no digging below the level of the water table. It is therefore important to ensure that the water table is deeper than the planned level of foundation before starting the excavation. The excavation must not constitute any risk of damages to neighbouring buildings, sewer and supply lines, public traffic areas or similar. Thus, conditions in the neighbouring areas can in some cases exclude foundation work according to conditions in low

foundation control class.

Dimensions

Based on the above presumptions deep strip foundation can be carried out without further investigations - using the values found in table 2.

Table 2 Dimensions of deep strip foundation under walls in small single length houses. The dimensions given require that the width of the house is less than 9 m.

Width of deep strip foundation in m Type of house

Under load-bearing and non-load-bearing external walls

Under load-bearing internal walls 1 storey with ground supported floor

1½ storeys with ground supported floor 2 storeys with ground supported floor

0.30 0.30 0.30 0.20 0.20 0.25 1 storey with crawl space

1½ storeys with crawl space 2 storeys with crawl space

0.30 0.30 0.35 0.25 0.35 0.35 1 storey with basement

1½ storeys with basement 2 storeys with basement

0.35 0.35 0.40 0.25 0.35 0.40

The foundation height should be chosen to at least 0.30 m under load-bearing internal walls. However, in houses with ground supported floor, at least 0.20 m. Brickwork chimneys and fireplaces require a foundation of the same height as stated for the deep strip foundations.

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The dimensions are valid for traditional single length houses that is, houses with

load-bearing facades and possible load-load-bearing longitudinal walls placed close to the centre line of the house.

Deep strip foundations shall have at least the same width as the wall above and should be placed symmetrically beneath this. In houses with basement where the foundation is used as abutment for the concrete slab in the basement floor, the foundation shall be at least 0.10m wider than the basement wall. This will usually be fulfilled if the width is chosen to 0.50m.

Non load-bearing internal walls can usually be founded directly at the floor deck concrete slab. The maximum linear and point loads, which can be transmitted, depend on the concrete slab and the insulating material. Reference is made to product catalogues from the insulation manufacturers . Alternatively non load-bearing internal walls can be founded on top of the capillary breaking layer, see figures 19 and 21 on pages 27 and 28.

If bracing walls are not founded as load-bearing walls one must ensure that the vertical reaction can be absorbed by the bed on which the wall is resting (e.g. concrete slab).

Workmanship

Foundation work starts by excavating an area similar to the geometry of the building - for example to a level corresponding to the upper side of the deep strip foundations (see figures 6, 7 and 8). However, topsoil must be

removed to a depth where the stratum is no longer weak and compressible (removal of layers containing organic material). Hereafter commences the excavation of trenches for the foundation according to dimensions (widths and depths) given in table 2. Dug out material must under no circumstances be filled back into the trenches. Notice that the foundation level (depth) shall at least correspond to the

see paragraph on concrete. Internal wall foundations in houses with ground supported floor shall only be taken down to load bearing subsoil, as they will not be exposed to frost (due to the temperature conditions under the house).

If the oversite excavation level is lower than the topside of the deep strip foundation the upper part of the foundation can be cast using formwork. Alternatively hollow blocks of concrete or clinker concrete as well as

massive clinker concrete blocks may be used.. The hollow blocks are stacked on the strip foundation with tight joints and bonding. When casting no more than two courses must be cast at one time using 5 or better. The concrete is carefully compressed with immersion vibrator. Horizontal construction joints shall be placed along the centreline of the blocks. Solid clinker concrete blocks are laid with filled joints using mortar KC

20/80/550 or better according to the “Code of practice for the Structural Use of Masonry” (DS 414) .

When oversite excavation reaches deep down it might be expedient to build the entire foundation of hollow blocks on top of a concrete blinding.

The underside of the foundation shall be horizontal. Stepping shall be carried out as shown in figure 9.

Where service lines are taken across the foundation, the foundation must be carried out according to figure 10.

Figure 9 The underside of deep strip foundations shall be horizontal and even. Stepping must have a maximum height of

Max. 0.60m

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SBI Direction 189,

KLJ 15

Figure 10. Where service lines cross the deep strip foundation, the underside of the

foundations shall be at least 0.1 m deeper than the crossing line at a distance of minimum 0.6 m on either side of the line. Trenches for sewer and drain pipes which are dug parallel to the foundation must not be dug deeper than the bottom of the foundation. . Inserts or recesses

To ensure the stability of the house it is often necessary to anchor the roof construction and/or the walls to the foundation. The placement of anchors must be determined prior to casting the foundation because the fixing of anchors can be done either

simultaneously to casting or recesses can be made in the concrete for later fixing. The same applies to the placement of branch drains, which will be further elaborated in the chapters; “Drainage” and “ Domestic Ground supported floor”.

Concrete

Concrete 5 or better is used, cf. table 3. According to” Code of Practice for the structural use of concrete” (DS 411).

the crushing strength of the concrete shall be controlled but factory control is considered adequate when concrete is supplied by a concrete manufacturer being a member of the “The Concrete Manufacturers’ Control

Board” (In Danish FBK) or “The Danish Concrete Certification” (In Danish DBC)

Furthermore, concrete can be mixed on site without strength control as stated in table 3. The slump range of the concrete should be between 60 and 100mm and must not exceed 150mm.

The requirements for concrete aggregates and the implementation of concrete work are described more thoroughly in the ”Code of Practice for the Structural Use of Concrete” (DS 411)

Concrete and light clinker concrete hollow blocks shall fulfil the requirements for strength class 3.0 Mpa and must be delivered from a factory affiliated to an approved control system (i.e. marked with a triangle). Solid clinker concrete blocks shall fulfil the requirements for strength class 2.6 MPa according to “Code of practice for the Structural Use of Masonry” (DS 414) and must be delivered from a factory affiliated to an approved control system (i.e. marked with a triangle or marked “LBK”)

Table 3. Concrete mixing ratio (cement: sand: stone)

Concrete type Mixing ratio according to volume Mixing ratio according to weight Concrete 5 Concrete 10 Concrete 15 1:4:7 1:3:5 1:2:3 1/4/6 1/3/4 1/2/2½

Normal foundation depth

Note:

According to new standards concerning concrete strength the values in the table are no longer applicable. When using prefabricated concrete it is recommended to prescribe concrete 4, 12 and 16

respectively

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Drainage

Houses shall be built in such a way that surface water, ground water and earth moisture do not cause damage. Hence, surface water shall be drained off by establishing an adequate slope in the ground away from the house, see figure 11. Where the subsoil is not adequately self-drained, that is where infiltration water does not quickly soak away by itself, drains shall be established along the external wall foundations of the house – a so-called perimeter drain. However, a perimeter drain can be left out in houses where the surface of the floor deck is more than 300mm above the external ground level.

The purpose of draining is to reduce or completely remove water pressure on construction carried out directly against the soil. In this way seepage in the construction can be minimised and building components below ground can be kept reasonably dry. Draining does not eliminate moisture and, depending on the circumstances, draining must therefore be supplemented with moisture insulation.

In this chapter only draining of houses in non-complicated situations will be described, that is where the ground water level is below the

drainage level. In this case, drainage only includes the draining off of infiltrated surface water.

Draining shall be carried out in accordance with the Code of Practice for the groundwater drainage of structures (DS 436) and Code of Practice for Sanitary Drainage - Waste-water installations (DS 432). A more comprehensive discussion on the subject can be found in SBI direction 185: Sanitary Drainage Installations.

Workmanship

A drain consists of two parts, namely the drainage pipe and the drainage fill. Drainage fill is a filter (for instance gravel) which ensures the collection and transportation of affluent water from the surroundings. At the same time it prevents unwanted pollution and possible blocking of the drainage pipe (in the form of sediments). Thus the filter shall be build of a material with a grain size that fulfils the so-called filter criteria (criteria that regulates the size and the grains in the filter and the grains of the surrounding soil). The drainage pipe, which usually consists of a perforated pipe (with slits and holes in the pipe wall) directs the captured water to e.g. established waste water installations. When building a filter the pore size and the flow

Figure 11. Ground levelling must drain surface water away from the house. On flat terrain the slope away from the house must be minimum 20 per mill (1:50) within a distance of 3 m. On sloping terrain the ground must be levelled on the side of the house where the initial level is highest, and an intercepting drain must be installed at the

intersection between the initial terrain and the

Flat terrain Sloping terrain

Perimeter drain Intercepting drain

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SBI Directive 189 KLJ

17 openings should increase from the

surroundings towards the drainage pipe. Drainage pipes shall be laid with a grade of at least 3 per mille. Due to the risk of frost damage the overall bottom level should be at least 0.60m below finished ground level. Moreover, the highest bottom level should be at least 0.3 m below the construction part to be drained. Excavations must not be carried out below the bottom level of the foundations. Pipe dimensions must not be less than 70 mm (as smaller dimensions may cause cleaning problems). Pipe and fittings must fulfil the requirements laid down in the Code of Practice for the groundwater drainage of structures (DS 436). Pipes without socket joints should not be used.

Figures 6,7 and 8 show examples of placing a perimeter drain. If the surrounding soil consists of clay (firm cohesive soil), the filter may consist of a layer of small pebbles (2-8 mm) or pea gravel (5-16mm). A coarser material may be used when 80mm perforated PVC pipes or similar are used. In sand and similar (noncohesive soil) a filter of well-graded sand with d10>0.3mm and

1,5mm<d50<2,5 will be suitable. In this case

the slits in the drainage pipe must not exceed 1,5 mm in width.

The designations d10and d50 refer to the mesh

size in a sieve through which 10 percent and 50 percent respectively of the filter material can pass.

A filter shall have a thickness of at least 0.10 m at all sides of a drainage pipe.

Protective wraps such as filter cloth with small pore sizes may cause clogging and as such they must not be used neither to substitute the filter nor as a supplementary filter to gravel fill.

When backfilling the excavation the topmost layer must have a thickness of minimum 0.20 m and must consist of a sealing layer (for instance topsoil mixed with clay) and the ground shall be re-established sloping away from the house, as described in figure 11.

Branch drain

A branch drain, connecting the capillary breaking layer to the perimeter drain, must be established below domestic ground floors and below basement floors – see figures 6 and 8. The branch drain secures the discharge of water from the capillary breaking layer and also serves as a pressure equaliser in order to prevent the radioactive gas radon from penetrating the building. At least two branch drains must be established per building. If the capillary breaking layer is divided into sections by foundations of internal walls, a branch drain must be established for each section.

External basement walls

Under normal circumstances external basement walls shall be drained by the use of a perimeter drain system which can capture the surface water which always seeps into the soil around a basement. The perimeter drain system shall be placed in such a way that that it can effectively drain the capillary breaking layer below the floor via a branch drain. Consequently, the bottom level in the drain pipe shall always be placed below the top level of the capillary breaking layer.

There are no special requirements for the material which is used as backfill above the filter. However, along the wall a so-called wall drain must be established. This drain captures and directs surface water to the perimeter drain, see figure 8. This drain can either consist of well-drained sand or gravel with d10>0,3 mm in a thickness of at least 0.2

m or an insulating material with properties for draining.

The primary function of the so-called drainage slabs (thin PVC slabs) is to insulate the wall against moisture penetration (not draining). Consequently they must always be used in combination with a wall drain (as described above).

Cleaning

Drains must be accessible to cleaning and consequently inspection chambers

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(manholes) and inspection junctions (the latter with a diameter of minimum 300 mm) must be established at selected bends and on level stretches at intervals not exceeding 60 m. Figure 12 shows some examples of placement of inspection junctions in a drainage system. When placing inspection junctions considerations must be given to the fact that

Figure 12 Example of placements of inspection junctions in a drainage system.

the tools used for cleaning may have difficulties in passing bends without the risk of damaging the pipe. As a consequence all bends must be accessible for cleaning from two sides via inspection junctions. Surface water must not be drained directly to the drainage system. It is, however, permitted to drain the insignificant amount of rainwater from light shafts or covered external basement stairways directly to a perimeter drain. It is not necessary to ventilate drainage systems.

Drainage

Drained water is usually discharged to a waste water installation. The connection shall be made to a 300 mm gully at least 0.2 m above the water level. The gully must have a sand trap, a gully trap and a rain water inlet. Also, the connection level must lay above the highest damming level in the main sewer system with the addition a safety factor of 0.3m. This type of “direct” connection must

Figure 13 Fascines shall be placed inside the property boundary and at least 2 m away from any boundary line. Furthermore, they shall be placed at least 25 m away from drinking water wells, inspection chambers and the like. The distance from the centre line of the fascine (longitudinal axis) and from the fascine extremities to domestic houses shall be at least 5 m. Fascines are build as 0.4-0.5 m wide stone-filled trenches with a horizontal bottom. Stones to be used could be 32/64 mm washed course gravel covered with filter cloth and a layer of soil of at least 0.3-0.4 m. The volume of a fascine in clay soil can be determined at 1 m3per 30 m2 rain area. When constructing fascines

Minimum 2 m away from non habitable buildings or basement Minimum 5 m away from habitable building or basement

Plot boundary Filter cloth

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19 only be carried out provided the whole

drainage system is situated above the maximum damming level of the waste water installation in order to prevent pollution of the drainage system. In cases where these conditions can not be fulfilled the connection must be made through a pump well. When the outlet from the pump well is situated less then 0.2 m above maximum damming level it must be supplied with a retention valve.

Protection against rats

In areas pestered by rats it is advisable to place a detachable grid (made from copper or galvanised steel) at pipe openings in the inspection chambers and junctions in order to avoid the penetration of rodents into the pipes.

Fascines

Whenever building as well as soil conditions are considered appropriate, the authorities may approve the discharge of water from roofs, smaller paved areas and drainage water directly into a fascine for percolation. For detailed design we refer to “Code of Practice for smaller drainage disposal systems for percolations into the ground” (DS 440)

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Ground supported floors

A ground supported floor is a floor construction resting directly on the ground. Ground supported floors shall be insulated against ingress of moisture and loss of heat. Also they shall be sufficiently sealed in order to prevent the ingress of air containing radon (from the subsurface). In the “Heat loss frame” (see chapter on Thermal Insulation) ground supported floors assume the U-value 0.20 and in case of floor heating 0.15. A domestic ground floor is usually constructed as follows: At the bottom a capillary breaking layer preventing the absorption of ground moisture into the floor construction. This layer is followed by a heat-insulating layer and next a so-called load distributing layer usually in the form of a concrete slab cast in situ, and finally a floor finish. When the floor finish is a joist floor, a minor part of the heat insulation can be placed on top of the concrete slab. Apart from the floor finish all materials used in the construction of the domestic ground floor must be non sensitive to moisture.

An extensive treatment of questions concerning moisture in ground supported floors can be found in “SBI Directive 178 -The moisture insulation of buildings”.

Ground conditions

Ground supported floors shall rest on a strata of subsoil which as a minimum fulfils the requirements applying to the level of oversite excavation, mentioned on p. 18. If this level is deeper than the underside of the capillary breaking layer the remaining gap must be filled with replacement material such as sand or gravel which is filled in gradually using watering and compacting (with a plate vibrator).

Capillary breaking layers

Capillary breaking layers may consist of : Pebbles, shingles or gravel with a minimum grain size of 4 mm;

Light weight clinker floor blocks or

polystyrene insulation slabs resting on a levelled gravel surface

The thickness of the capillary breaking layer shall be at least 150mm.

Heat insulating layers

Insulating material shall be pressure-resistant and may consist of for example coated loose light clinkers, floor blocks, pressure-resistant mineral wool batts, or polystyrene slabs. Concluding: Some materials can be both capillary breaking and heat insulating.

Concrete slab

The slab should be cast in minimum 100 mm thickness using concrete 15 or better, see page 19. Shrinkage reinforcement should be used, for example 5 mm reinforcement mesh with 150 mm grid placed in the middle of the slab.

When casting the slab the concrete must either have a plasticity which prevents it from penetrating the underlying layer, or it must be cast on top of a diffusion open underlay for example filter cloth.

Immediately upon casting the concrete shall be protected against drying up by covering it with a vapour tight membrane, for example polyethylene foil. It should remain covered for app. 8 days.

Floor finishes

When using moisture sensitive floor finishes, such as wooden floors on joists or floating floors containing wood, a damp proof membrane must always be placed on top of the concrete slab as the slab will emit construction moisture for a considerable period of time after casting.

A 0.15 mm polyethylene foil is suitable as a damp proof membrane. It must, however, be laid with an overlap of at least 200-300 mm. When using wooden floors on joists, the joists must rest on blocks preventing the rising of moisture, for example adjustable plastic

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21 concrete slab. In doing so, a softer insulation

material may be used. This reduces cost and also reduces the total thickness of the ground supported floor. In order to avoid condensation on the top side of the damp proof membrane, the major part of the insulating material must be placed below the concrete slab.

Radon-proofing

When the atmospheric pressure decreases radon rises from the soil together with air. The pressure differences in question are up to 0.1 atmospheres and consequently the ingress of radon can only be avoided by equalising pressure in the capillary breaking layer with the outside pressure. Simultaneously to this the ground supported floor must be made as airtight as possible. The concrete slab is considered airtight but it is necessary to secure tightness along the foundation as indicated in figures 18, 19, 20 and 21. Equalising pressure of the capillary breaking layer can be achieved by the use of a branch drain connected to the perimeter drain, as described in the chapter “Drainage”.

Examples of ground supported floors

The figures 14, 15, 16 and 17 show examples of ground supported floor constructions. Achievement of the indicated U-values at the shown insulation thicknesses requires the establishment of an effective interruption of the cold bridge where the floor construction meets the foundation.

The figures 18, 19 and 20 show examples where a heavy external wall meets the floor. In the remaining part of the foundation an insulating layer should always be inserted between the two leaves of clinker concrete. Solid clinker concrete blocks provide a considerable cold bridge – even when a vertical internal insulation is used. One should be aware that the inner leaf is not always airtight and this may result in the ingress of radon as the gas may penetrate through the insulation in the cavity. This can be avoided by the placing of a continuous layer of

Figure 14 Ground supported floor: Concrete slab with wooden joist floor placed on a capillary breaking and heat-insulating layer of loose light clinkers. The layer thickness required to achieve the U-value

0.20 depends on the l-class of the light

clinkers.

Figure 15 Ground supported floor: Concrete slab with wooden joist floor placed on a capillary breaking layer of shingles and a pressure-resistant insulating layer.

A wooden floor is very sensitive to moisture and a damp proof membrane must therefore always be placed on top of the concrete slab, as the concrete emits moisture during a considerable period of time after casting.

Concrete slab with wooden joist floor Wooden floor on joists. Damp proof membrane

Concrete 100 mm Loose light clinkers, coated

Loose light clinkersλ-class 80, 260 mm Loose light clinkersλ-class 100, 320 mm

Concrete slab with wooden joist floor Wooden floor on joists. Damp proof membrane Concrete 100 mm

Pressure resistant insulation,λ-class 39, 125 mm Shingels capillary breaking layer, 150 mm

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Figure 16 Ground supported floor: Concrete slab with wooden joist floor placed on a capillary breaking and heat-insulating layer of loose light clinkers. The layer thickness required to achieve the U-value 0.20 depends

on thel-class of the light clinkers

A wooden floor is very sensitive to moisture and a damp proof membrane must therefore always be placed on top of the concrete slab, as the concrete emits moisture in a considerable period of time after casting. To avoid condensation on the topside of the damp proof membrane the major part of the insulation material must be placed below the concrete slab.

Figure 17 Ground supported floor: Thin floor finish on a concrete slab placed on pressure resistant insulation and a capillary breaking layer of light clinkers. When using

bitumen felt as shown in figure 19. Consequently, the constructions in figures 18 and 20 are only radon proof provided the inner leaf is adequately airtight – also where it meets the concrete slab.

Figure 21 shows how a stud wall can be connected to a ground supported floor. Tightness against radon ingress requires a tight connection between concrete slab and wall, for example by the use of bitumen felt adhered to concrete slab and to internal wall surface.

Alternative solutions, which differ significantly from the ones shown here can be found in SBI Directive 184 “The heat loos of buildings and U-values”

The figures 18-21 show examples of the construction of load-carrying and non load-carrying internal walls on ground supported floors. Figures 19 and 21 show non load-carrying internal walls founded on the capillary breaking layer. Often it will be possible to place these directly on the concrete slab as shown in figure 20 and mentioned on page 18.

Foundations shall be so constructed that no damage can occur as a result of ground moisture. This is normally secured by rendering foundation blockwork on the outside (150 mm below ground level) and plastering the uppermost 150 mm (the visible part).

Concrete slab with wooden joist floor Wooden floor on joists.

Mineral wool ,λ-class 39, 50 mm Damp proof membrane Concrete 100 mm Loose light clinkers, coated

Concrete slab with thin floor finish Thin floor finish

Concrete 100 mm

Pressure resistant insulation,λ-class 39, 75 mm Loose light clinkers, coated

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23

Figure 18 The cold bridge through the upper part of the foundation (a) is broken by the use of clinker concrete blocks with an insulating layer in the middle. Radon penetration is avoided by suspending bitumen felt across the edge insulation groove and bonding it to the concrete slab. In cases where the inner leaf will be treated with a surface coating making it radon tight the bitumen felt can taken up along the wall - overlapping the surface coating- and bonded to this. (shown with a dotted line). The figure also shows a load-carrying (b) and a non load-carrying internal wall (c). Bitumen felt under the internal walls is bonded to the concrete slab.

Figure 19 The cold bridge through the upper part (a) of the foundation is broken by an insulating layer between two clinker concrete blocks in the topmost course. Radon penetration is avoided by suspending bitumen felt across the edge insulation groove and bonding it to the concrete slab. The figure also shows a load-carrying (b) and a non load-carrying internal wall (c). The latter is founded directly on the capillary breaking layer, see page 18. The foundation under the load-carrying internal wall is taken to the topside of the concrete slab and the damp proof course is bonded to the concrete slab.

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Figure T1.

Placing of door at the external foundation as in figure 18 (p. 27).

The concrete slab in the ground supported floor must be extended and the topmost clinker block must be changed along the door opening. Sealing against radon penetration is done by the use of bitumen felt, which is extended into the door opening. Additional floor joists are added in the door opening depending on the orientation of the joists

Figure T2

Placing of door at the external foundation as in figure 19(p. 27).

The concrete slab in the ground supported floor must be extended and the topmost clinker block must be

changed along the door opening. Sealing against radon penetration is done by the use of bitumen felt, which is extended into the door opening

.

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25

Figure 20 The cold bridge through the upper part of the foundation (a) is broken by the use of clinker

concrete blocks with an insulating layer in the middle. A damp proof membrane on the topside protects moisture sensitive parts of the floor construction. Casting the concrete slab on top of the foundation secures against the penetration of radon along the foundation. In case the internal leaf is not radon tight , an additional layer of bitumen felt should be inserted (as indicated with a dotted line). The figure also shows a load-carrying (b) and a non load-carrying internal wall (c). The latter is founded directly on the capillary breaking layer, see page 18.

Figure 21 The cold bridge through the upper part of the foundation (a) is broken by the placing of an

insulating layer inside the foundation. In this way the insulation in wall and floor is connected. Radon penetration along the foundation is avoided by bonding a strip of bitumen felt to the concrete slab and the wall. The figure also shows a load-carrying (b) and a non load-carrying internal wall (c). The latter is not always founded directly on the capillary breaking layer.

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Crawl space

The normal height for a crawl space ranges from 0,6-0,8 m. The purpose of a crawl space is to obtain a distance from the ground to the ground floor, to prevent contact with ground moisture. See figure 22. A crawl space must be protected from ground moisture and sur-face water.

The external wall must be constructed so that it can withstand the surrounding earth pres-sure.

Fire demands

The floor (deck) over the crawl space, be-cause it can be used for storage, must fulfill the same fire demands for a floor over a basement (BD 60 for 1 '/4 + 2 storey houses).

U-value

The deck over a crawl space must fulfill the heat frame demand of U-value 0,20.

Figure 22

Crawl space deck construction can be of prefabricated light weight slab with 100 mm insulation bonded to the underside. The outside edge of the slabs by the external walls, should be insulated in between the external leca blocks, to prevent thermal loss (cold bridge).

The timber floor construction over the slab must be protected from building component moisture with a 0,15 mm polythylen DPM, laid on the slab. 75 mm extra insulation is laid on the DPM to prevent condensation on the overside of the DPM.

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Figure 23

It is recommended that ventilation vents are placed every 6 meters in the external walls. Each vent must have a minimum cross area of 150 m2. The vents must be placed so that still air pockets are' prevented in the crawl space.

Air vents must be placed in internal walls when necessary, to create airflow from external wall to external wall.

It must be possible to inspect the full area of the crawl space by inspection hatches and openings. With regards to the inner walls stability the inspection openings must not be placed by the external walls. If the crawl space's deck is constructed in concrete or similar non-moisture sensitive mate-rial, the number of vents can be reduced by 50%, but there must be at least one vent at each corner.

Ventilation

Moisture, that enters the crawl space is re-moved by ventilation. For size and position-ing of vents see figure 23 and 24.

Crawl space floor

The floor in the crawl space is normally cast in 80 mm non reinforced concrete 5 or stronger. The concrete slab can rest on the ground if the top soil is removed. It is recom-mended to cast the concrete on a 0,15 mm polythylen sheet.

Crawl space external walls

Crawl space external walls can be constructed of concrete foundation blocks that are cast with concrete or of (leca) light weight con-crete blocks.

The external wall can also be cast on site in form work with concrete 10 or better. The walls must have at least the same thickness of load bearing walls above. The foundation blocks must be bonded together on a strip foundation and cast together highest two courses at a time with concrete 10. Horizontal joints must be placed in the concrete in the middle of the block. Leca blocks must be bricked up with full joints, with mortar KC 20/80/550 or better. The blocks can be reinforced with 2 pieces of BI steel or 2 pieces of 6 mm tentor steel in every 1/3 horizontal joint. The reinforcement must continue along the wall and around corners. Over lapping must be a minimum of 300 mm.

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Figure 24

The vents in the crawl space walls must be placed 80-100 mm over the ground and end under the crawl spaces deck (under side floor). A horizontal vent channel through the external wall can cause the ground floor level to lie too high over the ground. This distance can be reduced, if the vent channel is bent down and inwards. If so the channels cross section should be increased min. 50%.

The casting of the wall should be done at one time, the concrete must be compressed care-fully with vibrator.

Holes and indentations must be repaired with cement mortar 1:3.

To be sure of the walls stability, because of ground pressure, see max. wall size page 38. The house must also be stabilized against wind suction, with casting of anchors in the crawl space external wall or foundation, if the walls are constructedwith leca blocks. The crawl space's external walls must be moisture resistant. The walls of blocks must be rough rendered in the full height and then fine rendered on the visible part over ground level and 150 mm under ground level.

The rest of the external side of the wall mus' be coated with bitumen. The same for walls cast in concrete 10.

Filling out at the external wall must not be started before the crawl spaces floor is cast and internal cross walls are constructed. If a 4 sided supported wall is implemented then the deck over the crawl space must be con-structed.

Internal walls

Internal walls in crawl spaces are normally constructed in concrete foundation blocks, leca blocks, light weight concrete. The walls must be a minimum thickness of the load bearing walls above.

Minimum 80-100 Minimum

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Crawl space deck

The deck (floor) over the crawl space is normally constructed with timber floor joist or prefabricated elements of leca concrete. Under wet rooms the joists are replaced with concrete slabs.

Timber joists

For joists dimensions, see page 41. To obtain a U-value of 0,20, the joist con-struction must be insulated with approx. 200 mm mineral wool. Approx. 1/3 of the insulation shall be placed under the joists to prevent moisture concentration. The insula-tion must be fixed carefully so that air cur-rents do not penetrate the joints. The deck must be wind resistant so that draughts are prevented from the floor. This can be done by placing a DPM under the floor boards and fixing it at the back of the skirting board. This will also prevent radon expo-sure.

The floor joist construction must be insu-lated against moisture at the walls by laying a DPC of bitumen felt between the walls and timber.

The ends of the joist in the external wall and the joist sides by the external wall must be coated 2 times with timber impregnation paint.

Figure 25 shows an example of a timber joist construction, and figure 26 shows an example of a concrete slab under a wet room.

Figures 27 and 28 show examples of con-nections between joists and external walls. To limit the joists height it is normal to use a height of 150 mm as shown in figure 25. This will reduce the max span of the joists, therefore extra load bearing walls will be constructed in the crawl space. Foundations dimensions from table 2, page 17 can be reduced to the half of the given sizes though min. 0,15 m.

Mineral wool 39, 150 mm between joists

Stiff, wind resistant mineralwool boards 36, 75 mm Fixed under joists

U = 0,18 Figure 25

1/3 of the insulation placed under the joists. Reduce the insulation thickness between the joists to 125 mm, increases the U-value to

0,20.

Wet room with concrete slab cast in situ Floor tiles laid in mortar

Concrete slab with/without heated floor

Pressure resistant insulation, 30 mm Concrete slab

Insulation X-kl.36, 150 mm

fixed mechanically U = 0,19 Figure 26

Crawl space deck constructed with timber joists and concrete slab under a wet room. To keep the timber joists from the wet room, they are load bearing on brick piers.

•Timber joists over crawl space Floor boards

DPM

Joists 75 x 150 mm

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Figure 27

Timber joist crawl space deck. A cold bridge is avoided by placing c

vertical pressure resistant insulation in the middle of the wall. Heating pipes fixed under the joists are insulated independently. DPM laid directly under floor boards prevents draughts and radon from the crawl space.

Figure 28

Timber joist construction.

Cold bridge between stud frame and timber joists is prevented by placing insulation vertical over the leca block. The DPM must be bonded to the internal wall cladding to prevent draughts and radon. The bottom frame of the wall must be pressure

impregnated.

For dimension of concrete slab cast in situ, see page 42. Leca concrete deck can be developed in standard size and load bearing capacity.

To obtain a U-value of 0,20 the concrete and leca concrete must be constructed with insulation, 175 - 200 mm depending on the slabs own insulation ability.

With timber floor boards on battens or other sensitive floor coverings a DPM must always be laid on the overside of the concrete deck for protection against building component moisture.

In this case a layer of insulation max. 75 mm can be placed over the DPM to prevent condensation forming on the overside of the DPM.

Figure 29 is an example of a leca concrete with insulation cast on the underside. Figure 30 is an example of a wet room floor

construction on a leca beton slab. An example of the connection between slab and wall is shown in figure 31. The figures 32 and 33 are details of external door and slab construction.

Floor boards Timber joists

Mineral wool between joists Stiff, wind resistant mineral wool Boards under joists

Heating pipes under timber joists

Stud frame with timber cladding Electricity pipes on the warm side of the insulation

Floor boards, DPM Timber joists

Mineral wool between joists Stiff, wind resistant mineral wool under joists

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Leca concrete component over crawlspace

Floor boards on battens. Mineral wool 39, 75 mm, DPM.

Deck component, sandwich construction 160 mm density 600 kg/m3.

Mineral wool 39,100 mm.

Cast on component in the factory U = 0,20

Figure 29

Crawlspace deck of leca concrete

component with insulation. Only a minor part of the insulation must lay over DPM.

Figure 31

Leca concrete component deck as show in

figure 22. The deck construction isplaa as low as possible in connection to the ground level, approx. 150 mm underflow level.

If the level between in and out should be reduced even more, a trench could be established along the external wall.

Figure 30

Wet floor construction on leca

concrete components see page 29. If an extra 50 mm insulation is fixed on the underside of the deck a U-value ofO, 18 can be obtained.

Or to fulfill the heat loss frame the extra 50 mm insulation can be placed on another building component.

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Figure 32

Detail of an inward opening door with a construction as shown in figure 31. There must be a landing of steel mesh or ground raised to the same level of internal floor covering. There must be a gap between the raised earth and external wall to prevent moisture penetration. This could be achie-ved by placing a paving stone on its edge to hold the soil away from the external wall. The air gap should be so wide that it is possible to clean it for leafs, dirt etc. If the entrance is designed with an open porch a smaller open drain channel will be

sufficient.

Figure 33

Detail of outward opening entrance door with a construction as shown in figure 31. To be sure, that the door can open in all conditions, the landing should lay a min. of 20 mm under the doors leafs under side. The difference in levels can be solved with a steel meshed ramp etc. placed between the landing and external wall.

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SBI Direction 189

Translation RHT 34

Basements

A basement must be insulated against heat loss, moisture and radon penetration from the ground. The basements external walls must withstand ground pressure. The deck over an unheated basement must have a U-value of 0,40 or better.

Fire prevention

Basements external walls, load bearing in-ternal walls and deck must be constructed with a minimum of a BD-building component 30. In houses of 1½ or 2 floors and basement the load bearing construction must be con-structed as a BD-building component 60, and a stairway from basement to ground floor must be separated from the basement or ground floor with a minimum of a BD-building component 60 with a BD door 30. The walls and ceilings must be constructed with a minimum of a class 2 cladding. Basement floor

A basement floor is normally constructed with a concrete slab with contraction

rein-forcement, heat loss, insulation and a capil-lary breaking layer or a combined insulation and capillary breaking layer. The U-value for a basement floor is U-value 0,20. See figures 35 and 36. Radon penetration can be prevented by casting the slab floor and the external walls foundation and internal walls foundation as shown in figure 34. The concrete floor can rest on the ground

Basements external walls

Can be constructed of concrete or concrete foundation blocks or solid light weight con-crete blocks. Or can be cast in situ with shut-tering or form work with concrete 10 or stronger. They must have a minimum thick-ness of the wall it carries from above. See fi-gures 34,38, 39 and 40.

Foundation blocks are laid on a strip founda-tion in a bond and are cast out max two courses at a time with concrete 10 or stronger. Solid light weight blocks are laid with full joints with mortar KC 20/80/550 or stronger referring to masonry norm. There must be laid Bl-steel or 2 x 6mm tentor steel or similar steel with the same strength in every third horizontal joint. The reinforcement must continue along the wall and around corners. Overlapping must be a minimum of 300 mm. The casting of the wall should be done at one time, the concrete must be compressed care-fully with a vibrator. Holes and indentations must be repaired with cement mortar 1:3. If the basement wall is constructed as a cavity wall, it is recommended to fix an extra row of wall ties under the deck.

_A

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Figure 34

The section referring to low and high lying terrain. The top part of the external basement wall is constructed as an insulated cavity wall. The insulation in the cavity must overlap the external insu-lation with a minimum of 200 m. In this case the top part can not be counted as (with the basement deck) load bearing for ground pressure. The basement window is constructed on the outer leaf with a brick lintel and inner leaf with a prefabricated concrete beam A cold bridge is prevented with

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SBI Direction 189

Translation RHT 36

Concrete basement floor 100 mm concrete

Plastic membrane to prevent radon 100 mm pressure resistant insulation 150 mm capillary breaking layer of gravel Pressure resistant insulation X-kl. 39 U = 0,21 Pressure resistant insulation X-kl. 36 U = 0,20

Figure 35

Concrete slab basement floor with separate insulation and capillary gravel layer

Concrete basement floor 100 mm concrete

Plastic membrane to prevent radon 250 mm Ieca modules Wcl.80 U = 0,20

Figure 36

Concrete basement floor combined insulation and capillary layer of Ieca nodules.

The specified external basement wall in this, chapter fulfills the fire prevention demands and radon prevention recommendations. Filling in around the basement external walls must not start before the basement floor and internal cross walls are con-structed. If a 4-sided supported basement external wall is to be implemented the deck over the basement must be constructed, also before filling in.

Dimension

The soil pressures forces on the basements external walls, as a rule will only be sup-ported along 3 sides, the bottom side and two vertical sides, see figure 34; A basement deck of light weight concrete with correct construction detailing together with the basement walls, for example with

reinforcement to compensate for the weak-ened construction due to the cavity wall, can be classed as a 4-sided supported con-struction. Basement walls or non-reinforced concrete cast in situ (concrete norm 5.55) can be constructed in sizes given in table 4.

Table 4 Maximum sizes h x I for non-reinforced concrete 10 basement walls or foundation blocks cast but with concrete 10. h and I is given in figure 37.

Supported Wall thickness, _t

300 mm 400 mm 3-sided 4-sided 10 m2 15 m2 13,3 m2 20,0 m2

For wall thickness between 300 m and 400 m, the maximum

size is calculated with interpolation between the

SBI 189

SINGLE FAMILY HOUSES

SBI

189

2

EDITION

SBI-DIRECTION 189

1999

Contents

Preface

Introduction

Figure 1. The Building Regulations for Small Dwellings encompasses one

family houses up to 2 storeys and a basement. The houses may be detached

or semidetached. The Regulations do not apply to houses with separate

dwellings divided by a storey partition (horizontal division).

Loads, load acceptance and

load transmission

Foundations

Low foundation control class

Dimensions

Drainage

Ground supported floors

Figure T2

.

Crawl space

Basements