Building regulations when adding to the existing extension

[DIY master builder]

Hi everyone,

We’ve got a half width single storey rear extension built in the early 80s with no building regs sign off (was not required back then as built pre-1984).
The extension looks very well-built and doesn’t show any wear (apart from being a bit dated inside).
We want to build an in-fill extension on the other half and join with the existing one.

I’m going to dig a pilot hole and verify that the old extension has got some satisfactory foundations, but despite it all being in a good shape I am sure it won’t pass today’s BR so probably will need to be demolished and rebuilt.

Question - will the full building regs apply to the old extension?

Trying to see if we could do anything to retain the old extension and just build on the side of it.

Appreciate any advice on this

 

[jeds]

Only the new build requires a regulations application. Regulations require an application if you upgrade the main elements of the existing building - i.e. roof, wall surfaces, rendering, etc. or if you alter anything structurally or any controlled fittings - e.g. windows and doors.