PP for enlarging a window

23 Sep 2012
Reaction score
United Kingdom
Hi folks,

Short version: Do I need planning permission to enlarge the height of rear elevation windows in a dormer?

Long version: Hopefully a quick one. Have two windows in a dormer that are tiny and we are looking to enlarge. Can find plenty through searching on requirements for widening a window (in particular BC because of the structural changes) but can anyone advise on just enlarging the height of the window as we are content with the width and the dormer is timber framed so likely a nightmare to cut out above (and frankly unnecessary). BC required for thermal/safety etc. will be covered by use of a FENSA installer.

I did wonder if the size of the windows was dictated by planning permission for the dormer (undertaken by past owners of the house) but it appears actually they had plans included to build a lean to which would have come up to the bottom of the windows. They didn't get this far so we have the height available. I thought planning may have dictated small windows at high level because of overlooking but the nearest direct view of another property is probably c.50m but I may be mistaken.

Thanks in advance.
Sponsored Links
BC required for thermal/safety etc. will be covered by use of a FENSA installer.
Unless its changed (again!!) FENSA can only cover direct replacement window in the original size openings.
Sponsored Links
Yes if the dormer was built under a planning permission, you will need further permission to alter the window. Ask the planners, they may be prepared to treat it as a minor operation rather than a full application

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local