Here’s a question for the surveyors, architects, builders, and those with nothing better to do on a Saturday night:

Are two walls, built side by side along the property boundary, considered a single party wall?

Here’s the scenario. I live in the middle of a terraced row of houses. Me and my neighbours each have a single story extension across the full width of our houses. As far as I can tell the dividing wall between each extension is made from two separate walls butting up against each other, each wall supporting it’s own roof.

I now need to replace my roof which may need some work being done to my supporting wall. I’ll talk with my neighbours anyway but officially do I need to comply with the Party Wall Act (formal written notification, paying for surveyor if there is a dispute, etc)?

I’m sure they didn’t ask me when they replaced their roof a few years ago!

Not sure about repairs but for new stuff it’s within 3m I think.

if it really is two separate but effectively touching walls then it may not be a PW but there is nothing wrong with party wall agreements despite their bad press. keeps everything fair, reduces disputes and in event of dispute gives proper, independent way to resolve it. I’ve just done my attic and neighbours demanded one.
just talk to a sensible building surveyor who is experienced in PWAs.

Not

I think I should be able to avoid the whole issue by just replacing the roof and not touching the wall. Apparently there is no equivalent party wall act for roofs as they aren’t considered structural.

Provided the boundary runs between the two walls it’s not a PW. The boundary usually follows the centre of the main wall separating the two houses (which will be a PW).

No it doesn’t sound like a party wall scenario, but it would still be a good idea to take a schedule of condition of your neighbours place to protect your interests.