Extending using an existing outside cavity wall

[jordan8w]

The wall out the back of my house to retain clay is a cavity wall, the foundations of the wall are as thick as the house foundations, I'm wondering if I could do a single story extension off of the wall and just build up to the wall plate. My issue is what about DPC? Obviously there is no DPC in the existing wall. Do I have to knock it all down and then rebuild from the dpc course or is there a way I can do it without knocking it down.

 

[freddiemercurystwin]

Well ignoring the dpc issue for starters you'd have to insulate the wall internally, which is fine if you intend to build the rest of the extension like that but a PITA if not so I would say by all means use the foundation if it's suitable but probably more hassle than it's worth trying to use that bit of ropy wall.

 

[jordan8w]

Well ignoring the dpc issue for starters you'd have to insulate the wall internally, which is fine if you intend to build the rest of the extension like that but a PITA if not so I would say by all means use the foundation if it's suitable but probably more hassle than it's worth trying to use that bit of ropy wall.

Was going to fill the wall with the same type of insulation the house currently has, I wondered if they had planned for it as the wall is the exact size of the rear of the house.

 

[freddiemercurystwin]

That won't get you anywhere near enough to meet current regs.

 

[jordan8w]

That won't get you anywhere near enough to meet current regs.

Well I was planning to do it under permitted development and keep it single story, I was hoping worst case to only remove the inner skin add dpc and then build from there. Is this feasible?

 

[freddiemercurystwin]

PD has nothing to do with achieving the necessary Regs approval, and how will you fit the wall ties leaving just one skin? Honestly cut your losses, use the foundation by all means but the wall is not worth saving.