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Making back extension slightly bigger then plans

I have a approved back extension but after starting building work it is seen that it can be made 6 inches bigger by taking out a wall we own and building it at the wall side.

We have told the builders this who first agreed it will work and then after payment and getting the plans their supervisor says they have to follow the plans.

My question is i would like to make use of the 6 inches space as my neighbour has theirs built right up to the line aswell but the architect felt we wish to keep the wall for some reason.

Is this something i need to bring with architect, council LPA or leave as building work has started two days ago and they have nearly finished all the foundation and not worth the hassle?

4 Answers from MyBuilder Architectural Designers

Best Answer

Hello, if you've had planning approved there will be a condition on the decision notice that states you would have to build the extension in accordance with the plans. If you wanted to increase the size by 6inches then you would need to seek approval from the Local Planning Authority possibly by submitting a non-material amendment application. You would also need to check party wall details and notices may be required to your neighbour.


Answered 13th Sep 2019

Firstly I would suggest having a good discussion with your builders - and informing them of your desires and your concerns. It's important to maintain good working relationships - and therefore it's advisable to be very clear with your builders as to your reasons for reviewing the plans. Then I would insist on a meeting with the building inspector - with the senior builder present - to discuss any possible problems. There are issues related to party wall regulations, the affect on foundations - and visual aspects. When you speak to the building inspector you should ensure you have the full details of your Planning Permission with you - so that you can clarify the implications in relation to Planning laws - which address different issues and concerns compared to Building Regulations. If you are clear about your wishes - and engage everyone in open discussion you'll get the right answers and avoid taking risks which could lead to more major problems in the future.


Answered 18th Sep 2019

Richardson Architectural Design is right. You need to check with planning and look at the party wall issues. If your neighbour has built right up to the centre line of the boundary you need to check their foundation. If it’s flush with the wall it maybe deeper than the existing strip. You may need a structural engineer to look at that for you if you are abutting upto it.


Answered 24th Sep 2019

If it's permitted development then you don't need any permission at all, which a lot of rear extensions are, but you will need to speak to your architect as this will change the detail against the neighbours property.


Answered 1st Oct 2019

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