Do you need building regulations for new windows?
Planning permission controls IF you're allowed to build or change a structure. Building regulations control the quality and HOW you build a structure for safety purposes.
In addition to planning permission, you DO need to comply with building regulations for windows.
The main areas that building regulations cover for windows are:
- Thermal heat loss - windows are required to meet the minimum standards for the amount of heat they allow to pass through. This is measured as a U-Value.
- Safety glazing - in certain areas, safety glazing must be used to protect in case of an accident: for a door with glass up to 1500mm from floor level and for an unobstructed openable area at least 0.33 square metres and 450mm high and 450mm wide.
- Ventilation - for rooms such as kitchens and bathrooms with a high production of steam, mechanical fans and window ventilation are needed. For other rooms, standard windows and trickle vents are used.
- Fire safety - some external windows may need to be fixed shut to limit the spread of fire between properties.
- Means of escape - a replacement window can only be reduced to a size that a person can escape through (or it can be the same size). New windows must follow the criteria set for escape windows (see here).
If you want to read more about building regulations for windows, you can find a list of the most recent approved documents for building regulations here.
Instead of seeking approval for building regulations yourself, you have the option to use a registered installer (such as Everest) who are approved to carry out window replacement work.
The supplier will give you a certificate that shows the work was completed by a registered supplier and that the windows meet building regulations.
Building regulations Part O, reducing overheating in buildings
Prompted by climate change, additions to building regulations came into effect in June 2022.
As part of a drive towards reducing emissions, the regulations are intended to reduce overheating in houses by:
- Limiting unwanted solar gains in summer
- Providing adequate means of removing excess heat from a building
Part O relates to glazed areas of new build properties
Windows and glazed areas will be limited to a maximum size depending on:
- The floor area of the room
- The direction they face (south, north, east, west)
- If the building is in a high-risk area (London postcodes being the highest risk)
- Cross-ventilation inside the building (opening windows on opposite facing walls).
In high-risk areas, the use of external shading will be required. Internal blinds and curtains and tree foliage cannot be used for shading.
We recommend reading the documentation of Part O for full guidelines.
Part F relates to replacement windows in existing buildings
If the windows to be replaced currently have background (trickle) ventilators, then the replacement windows must have vents of at least the same size.
If the windows to be replaced don’t currently have background ventilators, then it must be shown that the ventilation will be made no worse than it was before the windows are changed. This may include having background ventilators fitted to the new windows.
It might be considered that a trickle vent could reduce the energy efficiency of the window, but this is not the case. Trickle vents can be closed so that the window frame is still air tight and draught-proof.
Vents are essential so that air can circulate in a room and remove any moisture in the air. This reduces condensation, mould and dampness which can be an issue in modern homes if they are not ventilated on a regular basis.
We recommend reading the documentation of Part F for full guidelines.