Removing 1 window and installing 2 in its place
HI, i am unsure of who can answer my question but here goes. We are looking at removing the 1 window in our bedroom and replacing it with 2 smaller windows to enable us to split the room giving each room its own window. Does anyone know whether this will require planning permission and what the approximate costs would be?
Asked by Ka on 1st Sep 2025
Expert Trade Answers
"Do you need planning permission?
Probably not if your house isn’t listed or in a special area.
But check with your local council to be sure.
How much will it cost?
About £1,000 to £3,000 to replace one big window with two smaller ones.
The price depends on window type and how tricky the work is.
What to do next?
Contact your local council to ask about planning permission.
Get quotes from a few window installers or builders"
Answered on 11th Sep 2025 - Member since Sep 2025 -
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"Hello Ka,
If windows are already within the same wall you should not have a problem and it does not require planning
Cost would range from £3,000 to £4,500"
Answered on 2nd Sep 2025 - Member since Nov 2023 -
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"You would not need permission, but l was to be asked for a price...l would have visit the site"
Answered on 2nd Sep 2025 - Member since Jan 2025 -
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"Wouldn't need planning for the windows put possibly for the extra room being created l, the rough cost of the window work would be in the region of £1000
Hope this helps
BLOA maintenance limited"
Answered on 18th Oct 2025 - Member since Oct 2025 -
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"Technically if you change the outside appearance of your property it requires planning permission. Ask your council planning dept it may simply be covered with a few photos and a letter.
Splitting a room does however require to meet minimum space standards to be classified as a habitable room. If it’s a rental you may then be required to obtain an hmo, change of use etc."
Answered on 3rd Sep 2025 - Member since Aug 2025 -
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"Hi! 🙂
In most cases, if you’re just replacing an existing window opening with two new ones of a similar style, it usually falls under permitted development and wouldn’t need full planning permission. However, if you’re altering the size/shape of the opening in the wall (making it wider, adding new lintels, etc.), then building regulations approval will definitely be needed, even if planning permission isn’t.
Costs can vary depending on:
• Whether brickwork needs to be cut out and new lintels installed.
• The type and size of windows you choose (uPVC being the most cost-effective, aluminium/wood more expensive).
• Labour rates in your area.
As a rough guide:
• Simple uPVC window supply & fit might start from £400–£600 per window.
• If structural changes are needed (new lintel, brickwork, making one large opening into two), you might be looking at £1,000–£2,000+ in total.
Best approach: get a builder/window installer to come and have a look — they’ll be able to tell you if structural work is needed and whether you should get building control involved."
Answered on 9th Sep 2025 - Member since Apr 2025 -
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"Unless you are in a conservation area or your building is listed . You wouldn’t need planning and worst case is you could apply for retrospective planning after work is done , if someone complains (unlikely ) including the cost of windows , possible and remedial work expect £800 to £1200"
Answered on 21st Oct 2025 - Member since Dec 2024 -
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"Planning: If it’s a house (not listed, not in a conservation area), swapping 1 window for 2 similar-looking ones is usually permitted development—no planning needed. If they’re upper-floor, side-facing, they must be obscure-glazed with limited opening. Flats/listed places usually do need permission.
Building Regs: Still required—use a FENSA/Certass installer.
Cost ballpark (Essex): ~£1.4k–£3k all-in (two uPVC windows plus splitting the opening/lintel and making good)"
Answered on 26th Sep 2025 - Member since Sep 2025 -
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"Hi
This is possible
Is either of the new windows looking towards your neighbours property ?
Hard go say a cost without seeing your property but £4400 to £7000 would be a fair guess
The work would need to be fensa registered or under building control
Hope that helps"
Answered on 1st Sep 2025 - Member since Jul 2025 -
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"If it doesn’t alter the front face of the properly it won’t require planning if it’s at the front can be done on permitted development and the cost would require a site visit"
Answered on 1st Sep 2025 - Member since Jul 2025 -
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