Building Regulations

Since April 2002, all replacement glazing has come within the scope of the Building Regulations. This means anyone who installs replacement windows or doors has to comply with new thermal performance standards. (Just replacing the glass is exempt).

When the time comes to 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 prove compliance:

  • A certificate showing that the work has been done by an installer who is registered under the FENSA Scheme

  • A certificate from the local authority saying that the installation has approval under the Building Regulations.

The FENSA scheme allows window and door installation companies that meet certain criteria to self-certify that their work complies with the Building Regulations. It was set up by the Glass and Glazing Federation, in association with all key stakeholders, and meets with central Government approval. 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 a firm which is not registered by FENSA, including work done as a DIY project by a homeowner, needs full local authority approval under the Building Regulations. You should note that you, as the homeowner, are ultimately responsible for ensuring the work complies with the Building Regulations.

Means of Fire Escape - Part B

Fire escape windows must provide an unobstructed opening of at least 0.33m² with a minimum dimension of 450mm in height or width. Single side opening windows will need to have a minimum frame width of 610mm to comply with building regulations and a 2 pane side opening window needs to have a minimum width of 595mm.

Ventilation - Part F

A trickle vent is a very small opening in a window or other building envelope component to allow small amounts of ventilation in spaces intended to be naturally ventilated when major elements of the design - windows, doors, etc., are otherwise closed. Build regulations state that you are required to replace windows like for like. If the old window already has a trickle vent your new window will need one fitted too. All windows to be fitted in new builds and extensions will require trickle vents.

Thermal Efficiency and Performance - Part L

Replacement windows and doors now have to meet the same standards as new windows:

  • UPVC Windows – U value = 1.6 W/m2.K and WER Band C

  • Doors – U value = 1.8 W/m2.K

U values are calculated for the whole unit, both glazing and frame.

Wheelchair Access - Part M

All new builds are required to meet building regulations Part M. This is to achieve a minimum clear opening width of 775mm. To meet this requirement, you would need to order an external door frame width of at least 950mm overall including the frame.

Toughened Safety Glass - Part N

The glass units in windows will have to be toughened if the lowest part of the window is 800mm from the floor. All glass units for doors must be toughened as windows that are connected to doors (side panels and flag windows).

The shaded areas shown in the diagram below show critical locations where toughened safety glass will be required.