Doors and windows come in for a lot of punishment over the course of their life. Barbour Index and Scott Brownrigg outline the standards for maximising their performance
Doors and windows are in constant use and must be usable for many years without any decline in performance. Unfortunately, countless examples show a direct correlation between poor specification and less than satisfactory quality. Because of this, the stringent standards for doors and windows must be rigorously applied.
1. Stability and mechanical robustness
The toughness and stability of the frame is vitally important for long-term durability. Size will also have an impact as larger doors and windows have significant forces at the fixings and through the frame. Weather conditions also play a part – stays, in particular, come in for exceptional loads in coastal areas. An assessment of how many cycles of operation will be needed should be carried out based on the required life and the type of use. British Standard 6375 Part 2 defines performance in terms of duty. Light duty must withstand 5000 cycles, medium duty 10,000 cycles and heavy duty 20,000 cycles.
The quality of materials, joining methods, weathering details, ability to withstand solar radiation as well as wind and rain, the quality of applied finishes and the cycles of use are all crucial to the assessment of durability. Refer to the following standards for guidance.
- BS 644 covers timber windows
- BS 4873 covers aluminium windows
- BS 6510 covers steel windows
- BS 7413 covers plastic windows
- BS EN 12400 covers windows and doors’ mechanical durability.
3. Thermal performance
Issues include cold bridging, resistance to condensation, seal performance and solar gain. The British Fenestration Rating Council’s (www.bfrc.org) classification scheme should also be considered.
- BS 5250 Code of practice for the control of condensation in buildings
- BS EN ISO 10077 Thermal performance of windows, doors and shutters – calculation of thermal transmittance.
The ability of the window and door to exclude the weather depends on the design, materials and build quality, which should be carefully matched with the conditions specific to the site.
- BS 5368 Part 2 and BS EN 1027 cover watertightness
- BS 5368 Part 3 Wind resistance
- BS 6399 Wind loadings.
5. Acoustic performance
Quite often, the acoustic requirement for doors and particularly windows is a significant consideration for the specifier. Double-glazing coupled with high-performance seals offers good acoustic performance. For enhanced levels of performance, consider using wider than standard double-glazing cavities.
A glass frame must be strong enough to support the weight of the glazing if the glass isn’t a main structural element. Occasionally fire resistance may also be required. Consider the recommendations of the Glass and Glazing Federation (www.ggf.org.uk).
- BS 5713 Specification for hermetically sealed flat double-glazing units
- BS 6180 Code of practice on barriers in and about buildings
- BS 6262 Covers glazing and safety in buildings.
7. Fire performance
Fire-rated doors and windows must be tested as a complete unit. The fixings must provide the same level of performance. Several organisations offer testing and on-site checking: BRE, Door and Shutters Manufacturers Association, TRADA and Intumescent Fire Seals Association. Fire doors must be specified as a complete unit.
- BS 476 Fire tests on building materials and structures
- BS EN 1634 Fire-resistance tests for doors and shutters
- BS 5588 Fire precautions in the design, construction and use of buildings.
8. Air infiltration
Building Regulations demand doors and windows be well sealed. Therefore the seals, the required testing and the installed performance all need to be specified clearly.
Testing in accordance with the Centre for Window and Cladding Technology principles, BS 6375 or draft standard DD171 can give a range of standards for air infiltration.
- BS 4255 covers the specification of gaskets
- BS 5368 Part 1 and BS EN 1026 cover air permeability testing
- BS 6213 Guide to selection of construction sealants.
Doors and windows are always heavy and often large so they must be detailed for easy and safe installation. Several companies now offer small lifting devices to help with on-site operations. The specifier should consider the need to hold the door or window in any position, in any conditions. Finger trapping hazards can easily be created. Cover strips are available to prevent trapped fingers in the hinge area. Building Regulations also require cleaning to be undertaken safely.
- BS 8213 is a code of practice for cleaning windows and doors.
The Secured by Design principles are the main reference for the specifier and can be followed easily. Ensure the required level of security is clearly identified and applied to the door or window construction, the fixing method and locking devices.
- BS 7950 Specification for enhanced security performance of domestic applicationsn BS 8220 is a guide to security for buildings
- BS EN 1063 covers security glazing.