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Utilising a boundary wall in a rear extension

If I have a brick boundary wall that is mine, can I utilise this as the outer skin of an extension with a cavity & new internal wall? Also would I need a party wall agreement for this, although it is only a boundary wall that I own/have responsibility for & is there specific building regs to adhere to for this type of build?



4 Answers from MyBuilder Bricklayers

Best Answer

Providing the wall in in good condition and the foundation of the wall is adequate then this should not be a problem. If the foundations are not adequate whilst digging out for the inner leaf you will then have the opportunity to underpin the existing outer leaf.
If your excavation is within 3m of a neighbouring building you should server a party wall notice on the neighbour.
As for Regulations you will need to comply with a number of relevant Building Regulations, you will need to make an application to Building Control who will oversee the work you are doing and offer advice on how to comply with those Regulations should you need it.


Answered 8th May 2019

I would not utilise a boundary wall for an extension the footings would be unsuitable and it's not fit for purpose.


Answered 31st May 2019

Boundary walls generally are not suitable because of footings ..
You could come inside and upto your side of the wall , and dig down 1m minimum And 600mm wide pour concrete foundation and leave a section of ground in so as not to undermine existing foundation And install a further pad at about 1.5m and install two prestressed lintels over ... building control officers like this solution as it negates any disturbance To existing foundations ..and. Then allows you to build right up to your boundary wall ..while only losing a small amount of space sectional foundations


Answered 2nd Jun 2019

If the wall and the foundations are in good condition and in a suitable condition to accept whatever you are wanting to do with it and your structural engineer is happy then yes you can use it. As for a cavity and inner leaf how about securing 100 mm rigid insulation to the inside of the wall secured by 100 mm x 25 mm treated timbers then board and skim finish. Again insulation thickness will have to be okayed by building control but it will save costs and give the same job. Before any of that you need an architect and structural survey to know the best way forward


Answered 20th Dec 2019

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