Adding an extension to a house still under construction

spupazza · 13-10-2025 07:34PM #1

Hi,

I am purchasing a house currently under construction in the new development and would like to enquire about adding a simple ground‑floor extension to the kitchen.

The proposal:

A- Extend the kitchen by approximately 19 m².

B- Move the existing patio door to the end of the new extension.

C- Work required from the developer: extend foundations, walls and roof/ceiling.

D- Electrical requirements: two ceiling light points and four wall sockets in the new area.

My questions:

Have you or other buyers had experience asking developers to accommodate such changes during construction?

2. Would this request normally require the developer to amend the estate’s planning application?

3. What steps increase the likelihood the developer will approve a change like this?

4. Given the relative simplicity of the work, what ballpark cost should I expect if the developer agrees?

Thank you for your help.

DOCARCH · 13-10-2025 07:48PM

Generally the house needs to be complete to then add an extension under exempt development regulations. I cannot see the developer entertaining this suggestion/request as it will effect their own 'sign offs' in relation to planning, building regulations, BCAR, etc. If an extension added during construction it would not be in complaince with the original planning permission.

Also the original planning permission would have to be checked if (even when the house is complete) an extension could be built under exempt development regulations. For some housing developments the original planning permission may preclude the construction of extensions as exempt development and planning permission required (not matter the size of the extension).

C3PO · 13-10-2025 07:54PM

in the current climate, I would be amazed if the developer/builder would consider this. Far to much trouble for a limited return. Also, how would you foresee the legalities working … would you be paying for the house before the changes are made?

spupazza · 13-10-2025 09:29PM

https://www.boards.ie/discussion/comment/123902911#Comment_123902911

Yes I would be paying for the house before changes are made, but I imagined as you're saying that in this climate developers may not even entertain the idea

blackbox · 13-10-2025 09:33PM

In my limited experience a developer doesn't want to make any changes. We only wanted a chimney changed and they wouldn't do it.

kippy · 13-10-2025 09:43PM

https://www.boards.ie/discussion/comment/123903187#Comment_123903187

There are a few variables but in the vast majority of cases this wouldn't be entertained.

j14 · 13-10-2025 09:43PM

A friend of mine did this but it was in 1989. The extension required seperate planning application and the main house had to be finished first but the builder left it so the house could easily be extended.

It was a seperate builder who completed the extension as the main builder was focusing on finishing the housing estate.

muffler · 13-10-2025 09:44PM

Personally I cant see this happening.

Mellor · 15-10-2025 11:35AM

https://www.boards.ie/discussion/2058426641/adding-an-extension-to-a-house-still-under-construction

I’d say it’s highly unlikely to be entertained unless you pay over the odds. Would require planning updated.
Do the kitchen cabinets also need to be modified?

https://www.boards.ie/discussion/comment/123903187#Comment_123903187

As the plans are changing, it’s more accurate to say you are buying the new house from the developer. So you should probably be hit for stamp duty on the total cost.

https://www.boards.ie/discussion/comment/123903239#Comment_123903239

FYI that’s just a normal extension and nothing like the OP. If the house is finished first, then most likely no planning is needed (under 40sqm limit)

Adding an extension to a house still under construction

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