To build off neighbour extension or not?

[Narthecius]

We are planning to build a single storey extension to the rear of our property, hopefully around 4m out and 3m high. Our house is a 1930s end-of-terrace.

 

Our attached neighbour's house has a half-width extension (constucted 20-30 years ago) built right up to the boundary of our property, extending approx. 3.7m out and 2.5m high.

 

I've been told that it would be best to seek a party wall agreement and build that side of our extension off the existing wall. There are reasons why I'm hesistant, but I understand leaving a gap between the properties isn't ideal either.

 

If we wanted to build completely separately, is there a recommended gap between the buildings?

 

Concerns:

 

• Our garden boundaries are not straight out from the house, instead they are a parallelogram, sloped in towards my garden. Because our neighbour's extension has been build straight off their house, this has left a small triangle of their land on our side of the fence. I imagine if I wanted to build on this land it might be complicated?
• We would want to build up to maximum 3m height - could this be done off the existing wall?
• If the neighbour wanted to knock down and redevelop their existing extension I guess this could be complicated.

 

 

 

 

 

 

 

 

[markc]

Do yourself a huge favour and keep your structure independent. You will need party wall agreement for digging footings close to theirs but much simpler than connecting to it.

[Narthecius]

Thanks @markc, that's definitely the way I'm leaning. Is there a recommended gap between the properties? I guess as long as it's big enough to get someone down there for access & prevent damp that's sufficient?

[markc]

15 minutes ago, Narthecius said:

Thanks @markc, that's definitely the way I'm leaning. Is there a recommended gap between the properties? I guess as long as it's big enough to get someone down there for access & prevent damp that's sufficient?

No minimum as far as I know. New build not far from me and I don’t think anyone other than a tiny child would get through the gap, seems stupid.

[Mike]

1 hour ago, Narthecius said:

Is there a recommended gap between the properties? I guess as long as it's big enough to get someone down there for access & prevent damp that's sufficient?

No minimum, but how badly do you need the space? You'd need at least 600mm to erect a narrow scaffold tower or squeeze through with a wheelbarrow. And the roof will normally have an overhang.