21 August 2008Since April 2002, all replacement glazing (including windows, glazed doors and roof lights) has come within the scope of the Building Regulations. That means anyone who installs replacement windows or doors has to comply with strict new thermal performance standards (replacing just the glass and not the frame is exempt).
One of the main reasons for the change is the need to reduce energy loss. The Building Regulations have controlled glazing in new buildings for many years but this represents a very small percentage of total building stock. It is also essential to improve the performance of the much larger numbers of existing buildings if we are to meet stringent national and global energy saving targets.
When you sell your property, your purchaser’s surveyors will ask for evidence that any replacement glazing installed after April 2002 complies with the new Building Regulations. There are two ways to show compliance:
1. a certificate showing that the work has been done by an installer who is registered under the FENSA Scheme; or
2. a certificate from the local authority saying that the installation has approval under the Building Regulations.
The FENSA Scheme
The FENSA scheme, which allows installation companies that meet certain criteria to self-certify that their work complies with the Building Regulations. A sample of the work of every installer is inspected by FENSA appointed inspectors to ensure standards are maintained and installers who fail to perform can be suspended or even excluded from the scheme. FENSA also inform local authorities of all completed FENSA installations and issue certificates to householders confirming compliance.
Any installation done by an installation company, which is not registered to self-certify, this includes work done as a DIY project by a householder, needs local authority approval under the Building Regulations. You should note that the house owner is ultimately responsible for ensuring the work complies with the Building Regulations.
WARNING: There have been reports of installers who are neither members of FENSA nor make applications to the Council. Remember, it will delay or even stop the sale of your home if you cannot prove the replacement glazing was done legally. Before you sign a contract to buy replacement glazing, be sure to ask whether the installer is able to self-certify. If not, an application will have to be made to your local authority for approval under the Building Regulations.
Should you choose the FENSA scheme, you should satisfy yourself that the installer is registered.
This can be done by contacting FENSA on 0870 780 2028 or www.fensa.org.uk
The Local Authority Scheme
Please see Submitting an Application
Requirements new glazing must achieve
Thermal insulation
See Approved Document L1
Replacement timber, Upvc or timber windows & external doors must achieve an average 'U' value of 2.0 W/m2K or less (steel and aluminum - 'U' value of 2.2 or less), and all windows & doors must use glass with a centre pane achieving a 'U' value of 1.2 W/m2K or less.
The 'U' value is a measurement of the rate at which heat is lost through a product or component. A lower 'U' value indicates a more energy efficient product.
Conservatories must be separated from the dwelling by either the existing door/windows/walls or new doors/windows/walls that comply with Part L of the Building Regulations 2002.
Structure
The opening in which the window or door is to be fitted should be made no larger than the existing. An assessment should be made by the contractor of the suitability of the existing support.
If a new opening is to be formed or the existing opening is to be increased in size then an application for the structural alteration will be required. Please contact Building Control for further information.
Means Of Escape In The Event Of Fire
See Approved Document B
All habitable rooms at first floor level and all rooms at ground level whose only escape is via another room (I.e. 'inner room') must be fitted with a suitable escape window.
An escape window must have an unobstructed openable area at least 0.33m2 and be at least 450mm high & 450mm wide (a 450mm wide window will need to be at least 735mm high). The bottom of the window opening must not be more than 1100mm and not less than 800mm above floor level.
Existing windows and/or rooflights (that are not to be replaced) within 'inner rooms' may be already be capable of being used as an escape window. In these cases the size of the opening & cill height should made no worse than before.
Means Of Ventilation
See Approved Document F
The existing area of ventilation openings (i.e. the openable area of windows & doors and the provision of trickle or night ventilators) should not be reduced. The table below shows current ventilation requirements.
| Room | Rapid Ventilation (i.e. opening window area) |
Background Ventilation (i.e. trickle vents) |
| Habitable Room | 1/20th of the floor area of the room | 8000mm2 |
| Kitchen & Utility | Opening window (no minimum size) | 4000mm2 |
| Bathroom/Shower Room | Opening window (no minimum size) | 4000mm2 |
| Sanitary Accommodation | 1/20th of the floor area of the room | 4000mm2 |
The each room must be provided with appropriate rapid and trickle ventilation (each window does not necessarily require trickle ventilators to be fitted).
Proximity To Flues & Chimney
See Approved Document J
If any new window opening or door is sited nearer a balanced or open flue terminal, then Building Control should be consulted. In all cases the boiler manufacturers advice should be followed with regard to proximity of opening windows or doors.
Protection From Falling
See Approved Document K
Where a first floor window cill height is less than 800mm from floor level suitable guarding should be provided to prevent a person (or child) falling through an open window. If this reduces the opening size of an escape window, then a restricted opening device could be used that can be easily overridden in the event of an emergency (child locks should be provided).
Disabled Access
If the property was subject to the Disabled Regulations (in effect from 25th October 1999), any new principle entrance should be no narrower than those existing, i.e. a minimum 775mm clear opening width with a low threshold.
Safety Glazing
See Approved Document N
Safety glazing must be provided in doors, windows adjacent to doors and windows at low level. Areas at critical locations need toughened or safety glass to complying with BS 6206: 1981. (i.e. Glazing in areas numbered 2,4,5,6,7,8,11)
Other Requirements
When replacing windows or doors, consideration should also be given to compliance with other parts of the Building Regulations, and must be no less suitable than those existing in relation to structure; means of escape in the event of a fire; means of ventilation; proximity to flues/chimney's; protection from falling; and disabled access.
