Do you need planning permission for changing windows?

This is omething I’m asked on a fairly frequent basis, what are the guidelines if you’re doing work around the house and you’re thinking of altering windows – is planning permission required?

The Department of Environment and Local Government has put together doing-work-around-the-house-the-planning-issues for planning exemptions for undertaking ‘Work around the house’. It covers the planning exemptions regarding extensions, shed and garages well and has this to say regarding alterations to a property:

External works of repair, maintenance and improvement such as painting or replastering do not need planning permission so long as they do not materially affect the external appearance…

So below is my opinion. And as I always say to clients, it’s just an opinion – another architect/engineer may have a different opinion (see disclaimer below).

• Changing windows or doors at the front of a house requires planning permission. Changing doors or windows is changing the appearance of the building from what it’s existing planning permission. NOTE: The ‘front’ in my opinion is the side of the house that faces the road.

• Changing windows or doors at the back of the house does NOT require planning permission (subject to planning exemption conditions). Here is my argument:

You are allowed to build an extension to an existing detached house of 40 square metres (again subject to planning exemption conditions). When you build an extension at this size you are allowed (effectively) to put in any new windows in any new configuration you like.

Therefore, what if you were only extending your house by only 1mm – you could still change all of the windows at the back of the house (subject) to the standard planning exemption conditions.

You could extrapolate further to the first floor in that you could equally build an extension (within the planning exemption conditions) at only 1mm and also have windows at that level at the BACK of the property. Bear in mind the different rules for terraced or semi-detached houses:

“for terraced or semi-detached houses, the floor area of any extension above ground level does not exceed 12 square metres, this includes any previous extensions carried out”

All instances should be taken on a case-by-case basis – see the disclaimer below!


All advice online is remote from the situation and cannot be relied upon as a defence or support – in and of itself – should legal action be taken. Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.

It is an offence to carry out any work that requires planning permission and the offence can carry very heavy fines and imprisonment. You can find out whether your work requires planning permission via a Section 5 Declaration to the Local Authority

It is an offence for a person to carry out either works or a Material Change of Use to which the Building Regulations apply without notifying the Building Control Authority via a Commencement Notice. The notice must be given to the authority not more than 28 days and not less than 14 days before the commencement of works or the change of use. Once validated by the building control authority, works must commence on site by the date specified on the Commencement Notice.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.