Removing 1 window and installing 2 in its place

Question

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?

Marius · Answer

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

Michael · Answer

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

Mike · Answer

You would not need permission, but l was to be asked for a price...l would have visit the site

Daniel · Answer

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.

Oleh · Answer

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.

Vincent · Answer

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)

Jason · Answer

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

Kyle · Answer

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

Removing 1 window and installing 2 in its place

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