Residential Property
This is a list of the one hundred most common issues raised in my experience in Building Survey reports requiring action by the client or giving rise to some warning in relation to a future repairing liability or aff ecting the value of the property. This list is not intended to be exhaustive but should be of interest.
1. Materials containing asbestos.
30. Leaking parapet and valley gutters.
31. Inadequate means of escape in the event of fi re from fl ats.
32. Poorly insulated ceilings in lofts.
33. Lack of party/fi re walls in old terraced roof spaces.
34. Sagging and spreading of roof timbers.
35. Condensation in old chimney fl ues.
36. Failure of damp-proof courses.
37. Leakage of water into wall cavities from concrete ‘ Finlock ’ gutters.
38. Cracked and leaning boundary and retaining walls.
39. Tree roots posing risk to structure.
40. Coastal erosion.
41. Failure of old lath and plaster ceilings and partitions.
42. Leaking gutters and down pipes.
43. Inadequate support when chimney breasts are removed.
44. Shortage of power sockets.
45. Inadequate ventilation to bathrooms and showers.
46. Inadequate ventilation to kitchens.
47. Poor septic tank and cess pit drainage arrangements.
48. Inadequate sub-fl oor ventilation to timber ground fl oors.
FIG 2.5 Condensation between the glass in double-glazed sealed units generally arises when the windows are between 10 and 20 years old, often (and conveniently
for the manufacturers), just after the 10-year guarantee period has run out. The sealed units then have to be replaced. The cost/benefi t and payback calculations for double glazing need to refl ect the fact that these windows are not maintenance free. During a Building Survey, it is necessary to check any condensation on the glass to see if it is inside, outside or between the panes. If it is between the panes, there is likely to be a developing problem with the windows which could be expensive for the client.
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85. Removal of internal walls and chimney breasts compromising structural stability.
86. Use of spiral and open riser staircases which do not comply with Building Regulations.
92. Lack of asbestos management arrangements for common parts to blocks of fl ats.
93. No proper pavement crossover for forecourt parking.
94. Storm water soakaway systems completely blocked and needing relaying.
95. Hot-water pumping over into loft header tanks.
96. Furring up of cylinders and pipework in hard water areas.
97. Failure to obtain listed building or conservation area consent where these apply.
98. Thermal expansion and contraction causing cracks to Calcium Silicate brickwork.
99. Death watch beetle in old damp hardwoods especially Oak.
100. Neighbours undertaking works to party walls without necessary agreement.
It is interesting to compare this list with the list I prepared in 1980 for the fi rst draft of this book and how clients ’ concerns have changed. The three main issues raised by clients still seem to be cracks, damp and the roof. But we now also have asbestos, radon, fl ood-ing, contaminated land and electromagnetic fi elds generated by pylons and mobile phone masts together with a much greater concern with the standard of fi nish and how the services work. Some of these issues have arisen as a consequence of the additional environmental and other searches made by conveyancers and media coverage.
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FIG 2.6 During the survey any ladders used must be properly angled and grounded. A 4 to 1 ratio of height to distance is best. Steeper and the user may topple backwards; shallower and the ladder may slide from beneath.
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And every one that heareth these sayings of mine, and doeth them not, shall be likened unto a foolish man, which built his house upon sand; and the rain descended, and the fl oods came, and the winds blew and beat upon that house;
and it fell: and great was the fall of it.
St. Matthew VII 24 – 27
I
well remember the long hot summer of 1976. The previous year had also been quite dry so we started with reduced water reserves in the reservoirs, and as 1976 pro-gressed the dry landscape of England came increasingly to resemble that of Spain or even North Africa. Properties built on clay soils began to crack and by the autumn there was widespread subsidence damage to buildings especially in the London area.Readers familiar with the workings of insurance companies will know that they rarely give away something for nothing but a few years earlier, at the beginning of the 1970s, the insurance companies, at the behest of the building societies and other lenders, had agreed to extend the cover off ered in the standard household insurance policies they issued. These policies, which started life just covering properties for fi re, had been pro-gressively expanded to deal with storm damage, burst pipes and other perils. And in the 1970s the cover was extended to include subsidence and landslip (and later heave) with the general level of premium unchanged.
CHAPTER 3
Foundations
An unintended consequence of this largess by the insurance companies was that fol-lowing the drought of 1976 there was a massive increase in the number of insurance claims for subsidence and many builders, seeing an obvious business opportunity, set themselves up as underpinning contractors and started to tout for the repair work which was being funded by insurance claims. Claims escalated and the unhappy insur-ers found themselves paying out hundreds of millions of pounds in exchange for no commensurate increase in premiums.
When undertaking a building survey, it is essential that the surveyor has a full under-standing of the principles involved in foundation design both in terms of modern practice and also what was done in the past, and it is important to be able to distin-guish between evidence of movement and cracks which may be of little consequence (although perhaps alarming to the client), and those which may indicate something seri-ously wrong below ground. In those cases where further investigation is needed then it is normal to refer the client on to a structural engineer unless the surveyor concerned is also qualifi ed in that fi eld.
Design
Modern foundations for simple low-rise buildings are likely to be either shallow strip, deep strip, pad-and-beam, pile-and-beam or raft. Each type has advantages and disad-vantages and will be suitable for some conditions and unsuitable for others. It should be bourne in mind that builders will generally use the most economical foundation which will satisfy the building inspector or district surveyor at the time, and fashions in foundation design change.
Older buildings erected before modern concretes became generally available, often had very little in the way of foundation at all. Common practice in the 19th century and earlier, especially in rural areas, was to dig shallow trenches and lay a brick footing on a bed of hoggin perhaps about 500 mm below ground level. It is surprising how well many buildings erected in this way have stood the test of time.
Surveyors often fi nd themselves inspecting foundations exposed for some reason, and it is common to fi nd that the actual foundations diff er from what the plans, or normal practice, would have required. Often the foundation depth in particular will be shal-lower than expected, indicating poor supervision during the course of the works because the builders excavating the trenches would have stopped digging as soon as they could persuade whoever was in charge that they had dug far enough.
I remember once supervising the construction of a small shop extension in Staines in Middlesex close to the Thames where the subsoil is a very variable mix of alluvium and river terrace gravels. The builders had to dig the trenches by hand because there was no access for machinery. Every so often they would stop and ask me to look at the bot-tom of the trench. At one point they complained that they must, by now, be down to Roman Staines if not deeper and surely they could now stop and place the concrete.
I was not happy and told them to carry on digging. Shortly after, they uncovered a fl uo-rescent light tube. Not something one associates with the 1st century BC .
31 Design
Foundations are not normally exposed for inspection during a building survey. The Royal Institution of Chartered Surveyors (RICS) practice note does not require this and most standard terms and conditions of engagement specifi cally exclude this type of intrusive investigation in the fi rst instance.
A surveyor must not be afraid of stating an opinion on a foundation when sure of his or her ground (in both senses), neither should surveyors be reluctant to refer a client to a specialist engineer when this seems appropriate. This is when local knowledge can be invaluable. Some surveyors have actually seen the buildings being constructed in their area and know fi rst hand what type and depth of foundation was used.
Stepped footings
Shallow concrete strip 500–750 mm below ground Slate dpc
Unrendered brickwork
Oversite concrete 75 mm
Quarry tiles Plaster
FIG 3.1 Late Victorian foundation, circa 1900.
The old Building Regulations laid down the following standards for foundations:
Foundations must (a) safely transfer all dead, imposed and wind loads to the ground without settlement or other movement which would impair the stability of, or cause damage to, the building or any adjoining building or works; (b) be taken down below frost damage or soil movement levels; be resistant to attacks by sulphates or other deleterious matters in the subsoil.
In England and Wales, a depth of 450 mm is suffi cient to place foundations below the level of frost damage in the most extreme conditions for which provision ought rea-sonably to be made. In practice a greater depth than this is generally advised because ground conditions on the surface of a site may vary, and foundations must always be taken down below the level of any disturbed topsoil. A minimum depth of 900 mm is therefore recommended unless the bearing subsoil is a hard rock formation or similar base of undisputed strength and regularity.
Subsoils
Care is required on chalk soils to ensure that the foundations are at least below the minimum for frost damage since chalks can be subject to considerable frost heave close to the surface.
Despite Biblical claims to the contrary, sandy soils make good foundation bases in many cases, although high-frequency vibrations in the range of 500 – 2500 impulses per minute can cause serious settlement problems, a point unlikely to arise with residential structures unless near to machinery. This factor should be borne in mind when dealing with indus-trial structures, particularly in the case of changes of use involving machinery.
On shrinkable clay soils a foundation depth of 1200 mm is recommended which would be below the level of seasonal change on level sites in the absence of vegetation. On sloping sites rather greater depths are required, especially on south-facing slopes where the ground will drain and dry out readily during periods of dry weather.
The presence of trees or bushes on shrinkable clay sites causes a particular problem for surveyors advising a prospective purchaser. The standard against which the property should be judged should be that set out in the appropriate British Standard. (BS 5837, 1980 ‘ Code of Practice for Trees in Relation to Construction ’ ). This BS states: ‘ Where the presence of shrinkable clay has been established and where roots have been found
Solid 225 mm brick work Pebbledash
Rendered plinth bridging dpc
Two-layer slate dpc
Grounds
Tongued-and-grooved boarding 100 mm 50 mm joists at 400 mm centres
100 mm 50 mm sleeper plates Bituminous felt dpc
Honeycombed sleeper walls
100 mm oversite concrete
Concrete strip foundation 750–900 mm from ground level
Hardcore fill
Ventilated sub-floor area, vents at 1.5 m centres
FIG 3.2 Typical 1930 domestic foundation.
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or are anticipated in the future, it is advisable to take precautionary measures in the design of the building’s foundation (in accordance with CP 2004, 1972 and CP 101, 1972). Alternatively, consideration should be given to designing the superstructure to accommodate any foundation movement that might be induced by clay shrinkage.
Where a subsoil investigation has not been carried out, an approximate rule-of-thumb guide is that on shrinkable clay, if risk of damage is to be minimised, special pre-cautionary measures with foundations or superstructure should be considered where the height or anticipated height of the tree exceeds its distance from the building. ’ One should pause for a moment to consider the full implications of BS 5837. In most cases the property being inspected, whether residential, commercial or industrial in character, is unlikely to have special foundations of the type anticipated, unless it is quite modern. Generally a short-bored pile-and-beam foundation, or pad-and-beam, or occasionally a raft design, would be used to accommodate the seasonal ground move-ments induced on clay sites by tree roots. (A sketch section through a pile-and-beam foundation is shown in Figure 3.3 .) It follows that for most older structures on clay sites a traditional shallow foundation design may be assumed, and that if trees are present whose height at maturity will exceed their distance from the walls of the structure,
Subsoils
Short-bored pile Reinforced ground beam Polystyrene packing
100 mm oversite concrete Slip plane
Fully-spanned timber floor Flooring-grade chipboard
Loosely-laid polythene membrane (optional)
Ventilated sub-floor area, vents at 1.5 m centres
FIG 3.3 Modern short-bored pile foundation for domestic and other buildings. Common 1990 foundation.
then the structure is at risk from shrinkage of the clay subsoil and damaging founda-tion movements would be possible during a dry summer.
Accordingly, the surveyor should make a note of the locations of all trees and bushes near the building being inspected and record their distances from the main walls, and identify the species of tree involved, confi rming whether or not the subsoil may be shrinkable. It should also be confi rmed whether specifi c trees or bushes may be within the curtilage of the property under review, or in adjoining curtilages.
The surveyor should then comment and warn the client as necessary in the light of cur-rent knowledge. Three separate situations may arise. A building with shallow foundations on shrinkable clay may have trees within the curtilage closer to the structure than their mature height. In similar circumstances there may be such trees but they may be located in an adjoining curtilage under other ownership. Possibly there may be trees within the curti-lage of the subject property which, while well back from the property concerned, could be a threat to an adjoining structure and thus give rise to a legal liability in the future.
If trees are closer to the building than the recommended distances, and within the curtilage, some action in the nature of removal, crowning, pollarding or simply subject-ing to a period of observation and future prunsubject-ing, may be advisable dependsubject-ing upon the circumstances.
If trees in other ownership are closer than would be recommended then the surveyor could advise the client to write to the owners of these trees, pointing out that their root systems could be hazardous to the property he is acquiring, and suggesting that further advice be taken in the light of the fact that by virtue of the laws of nuisance the owner of a tree is liable in law for damage caused by its roots extracting moisture from the subsoil under adjoining structures. (See Bunclark v. Hertfordshire County Council (1977) 243 EG 455 reported in Estates Gazette , 30 July 1977.)
Conversely, in a situation where trees within the curtilage of the property being acquired could pose a threat to adjoining structures, then the client should be warned of his own potential liability under the law of nuisance in case this should become sig-nifi cant in future years.
Certain species of tree are really unsuitable in a garden setting on shrinkable clay soil, particularly poplars, willows and elm, and if these are found they should be regarded with a critical eye. Poplar roots can extend for a distance of up to twice the height of the tree in search of moisture. I have also found ash trees to have searching root sys-tems, and a particular liking for entering cracked drains and disturbing paving, quite apart from their possible eff ects on shallow foundations.
It is recommended that surveyors practising in localities where shrinkage clays are found should familiarise themselves with the various aspects of this particular prob-lem, and that they should be able to identify any species of tree encountered during their work where this seems necessary. The reader may fi nd Trees in Britain, Europe and North America by Roger Phillips (Pan Books) to be a most useful guide to tree identifi ca-tion throughout the seasons.
One factor which can commonly cause problems with older foundations is subsoil ero-sion caused by cracked or leaking drains, or leaking water pipes. Unfortunately, storm
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drains and gullies to older property were rarely constructed well and soakaways will often have become blocked after the passage of time so that a point-discharge of water into the subsoil immediately adjoining the main walls will often occur. This can be damaging, especially to foundations on light sandy or silty soils which erode easily.
Clients should be warned of the importance of maintaining both foulwater and storm-water gullies and drains in good order and to avoid any point-discharge of storm-water into the subsoil adjoining the main walls.
Good building practice is to maintain foulwater drains in a watertight condition in normal use and to lay storm drains watertight for a distance of 3 m from any structure.
After this distance, storm drains may be laid as open-jointed land drains if required, and may run to soakaways if alternative stormwater sewers are unavailable and the soil is suitably porous.
Clients will rarely give a thought to what happens to the storm and foulwater dis-charges from their property and their signifi cance unless these points are described,
Subsoils
FIG 3.4 This settlement fracture has been poorly repaired and opened up again indicating continuing movement.
and their importance to the structure is discussed. In practice, lack of access to storm drains will often preclude any description of the actual system by the surveyor.