Materials

All the materials used for each part of the conservatory should be suitable for their intended location and use. There are primarily three framing materials and combinations of these mate- rials used, Aluminium, PVC-U and Timber as well as the glass and/or polycarbonate roofing material. The materials and their combinations are designed for a specific purpose and should not be substituted without prior consultation with the product designer to ensure the performance will be suitable. Steel can also be used in a conservatory, however, this is pri- marily to assist with the structural stability.

5.2.1 Aluminium

Aluminium is widely used as the principal roofing framework because of its strength and light- weight properties. It is often clad with PVC-U.

Aluminium extruded sections shall be produced using aluminium alloy complying with BS EN 755-9. Complete aluminium framed conservatory systems, often powder coated, are now available with dual colour.

All exposed aluminium profiles shall be finished with one of the following treatments: A powder coating complying with BS 6496

A liquid organic coating to BS 4842 Anodizing complying with BS 3987

Section 5 - Superstructure Design

5.2.2 PVC-U

PVC-U has excellent durability and requires very low maintenance without the need for spe- cial coatings.

PVC-U is used to manufacture wall frames and can be reinforced with aluminium or galva- nized steel for additional strength. It is also used in conservatory roofs where, in most cases, it is reinforced with structural aluminium supports.

PVC-U rainwater and drainage systems are similarly the most widely used and will match the PVC-U in the conservatory and should meet BS EN 12200-1.

Specifications for Extrusions used for roof and Wall frames:

White PVC-U extrusions should comply with BS EN 12608, (the scope of this standard in- cludes specifications for colour fastness and mechanical properties).

Wood grain or surface covered extrusions should comply with the requirements of BS 7722, or should have an independent product approval by a recognized Certification Body.

5.2.3 Steel

Steel can be used as a structural material within the conservatory construction; the following criteria should be adopted.

Hot rolled steel sections when tested in accordance with BS EN 10002-1 shall have ultimate strength between 355N/mm² and 510N/mm².

Formed sections shall be produced from steel sheet complying with BS1449-1. Pre-galvanized sheet should have a minimum sheet thickness of 1.2mm and complying with the tolerances within BS ISO 16162.

Components made from mild steel should be protected against corrosion by one of the fol- lowing types of finishes:

a) Hot dip galvanizing to BS EN ISO 1461 b) Zinc sprayed coating to BS 2569-1.

c) Powder coating shall comply with BS 6497.

5.2.4 Timber

Timber can be used for both the main conservatory roof members and the wall frames since it has both structural and aesthetic properties.

The Timber used should comply with BS EN 942, this standard defines the classification of sections as:

Window frames and main conservatory members Class J50 Casements and sashes Class J40

Small section beads (less than 15mm sq) Class J10

Section 5 - Superstructure Design

The moisture content appropriate to the end use of the conservatory is important in order to avoid problems resulting from shrinkage or swelling after installation. It is recommended that the external joinery should have an initial moisture content of between 13% and 19%.

5.2.4.1 Preservatives and finishes

The durability of some timber species can be upgraded by treatment with preservatives, the formulations of preservatives and the methods of treatment should comply with BS 8417. Treatment should be carried out after any machining of the timber sections is completed. Ex- ternal finishing systems will further protect against moisture and UV light, while providing a wide range of colour options. Only exterior quality paint and stain finishes should be used (BS 644 Annex A provides advice and recommendations for finishing of external joinery).

5.2.4.2 House Longhorn Beetle

In the geographical areas listed below, the softwood timber in the conservatories should be adequately treated to prevent infestation by the House Longhorn Beetle:

The Boroughs of Bracknell Forest, the parishes of Sandhurst and Crowthorne, Elmbridge, Spelthorne, Surrey Heath, Rushmoor, the area of the former district of Farnborough, Woking, the Districts of Hart, the parishes of Hawley, Yateley, and Runnymede.

5.3 Glazing

The specification of the wall frame and roof glazing should con- sider safety, loading conditions, thermal insulation, solar control and aesthetics.

5.3.1 Vertical glazing

Conservatory glazing shall meet the requirements of Approved Document N1 of the Building Regulations.

5.3.2 Overhead glazing

The glazing materials selected for conservatory roofs shall comply with GGF Data Sheet 5.7.1. Guide to the selection of glass and plastics glazing sheet materials for overhead glazing in con- servatories.

Consideration should be given to the installation of self-cleaning glazing or low maintenance glass (see 5.3.5 below) in conservatory roofs.

Conservatory roofs fitted with self-cleaning or low maintenance glazing must be constructed with a minimum pitch to ensure the correct operation of the self-cleaning glazing.

Tip

For very large areas of full height glazing that may be confused for an

open door, consider manifestation (marking) to make the glazing ap-

parent. NB. For practical purposes and as a requirement for

the GGF Conservatory Association Members, all glazing must conform to BS 6262

Section 5 - Superstructure Design

5.3.3 Insulating Glass Units, (IGUs)

IGUs shall comply with BS EN 1279 and be installed in accordance with the GGF Data Sheet 4.2.

5.3.4 Plastics glazing materials

Plastics glazing sheet materials shall be installed in accordance with GGF Data Sheet 5.7.8

Guide to the installation of hollow section plastics glazing sheet in conservatories or BS 5516

Code of Practice for design of sloping and vertical patent glazing. Specific guidance to the design and selection should be sought from the system manufacturer.

5.3.5 Self-cleaning glazing and reduced maintenance coatings

Easy clean glazing will aid the removal of dirt. Self-cleaning glazing will actively break down and loosen particles of dirt. The degree of the self-cleaning effect will vary according to the type of deposit and the exposure of the glass to water and sunlight.

These types of glazing will typically have a special external coating and should be installed and maintained in accordance with the manufacturers’ literature, any sealants and glazing trims must be compatible with the coating. Compatibility of patination oil and glazing materials must be ensured.

5.3.6 Applied glass films

Films may be applied to the glazing to alter its solar control or light transmitting characteristics. Refer to manufacturers’ information or GGF Data Sheets for further information.

5.3.7 Fire-resisting glazing

Where glazed conservatory walls are located on or in the proximity of the properties boundary or close to another building, the use of fire-resisting wall frames, including glaz- ing, should be considered in accordance with the requirements of Building Regulation B4 ‘External fire spread’.