Extension party wall drainage - leave a gap or not?

[Key1004]

Hi everyone,

I'm going to do a rear extension, and as from the attached photo, my neighbour has already extended a bit, and we have signed the party wall agreement with them.

My builder suggested to not build a wall alongside my neighbour's, instead, they'll build a new wall and leave about 15cm from my neighbour's wall for hanging the gutter pipe.

I have huge concern about leaving that narrow gap because of various reasons - damp, trapped animals, unable to maintain. I have expressed my concerns to my builders, but they said no need to worry and it's all standard. so I really need your help advice me what to do.

Thanks a lot!!!

 

[freddiemercurystwin]

No need to worry and it's all standard.

 

[Key1004]

No need to worry and it's all standard.

I saw some other people do their extension is to build the wall alongside the neighbour's so there's no gap in between. My builder said it's better to leave a gap, but I'm really not sure.

 

[freddiemercurystwin]

Not sure I follow, you want to build 'alongside' - so you don't want a gap or you do if so what gap do you want? In anycase you cannot overhang the boundary, wherever that may be. 150mm is fine , an animal won't get trapped, you can get a broom head or whatever down there to rake out any leaves etc should that happen, more than adequate for ventilation, the finish on the wall should be one that requires no further maintenance, it lets the builder enough gap to work, depending on the fascia detail etc.

 

[^woody^]

I need to check my gaps for dead animals that were previously trapped

 

[Key1004]

potentially, the walls

Not sure I follow, you want to build 'alongside' - so you don't want a gap or you do if so what gap do you want? In anycase you cannot overhang the boundary, wherever that may be. 150mm is fine , an animal won't get trapped, you can get a broom head or whatever down there to rake out any leaves etc should that happen, more than adequate for ventilation, the finish on the wall should be one that requires no further maintenance, it lets the builder enough gap to work, depending on the fascia detail etc.

can end up like this

 

[Key1004]

I need to check my gaps for dead animals that were previously trapped

how do you feel? would you done it differently if you can?

 

[freddiemercurystwin]

What am I looking at?

 

[Key1004]

What am I looking at?

this will be the gap between my and the neighbour's external walls, it's going to be very narrow. I don't know if sealing this gap and do a parapet gutter is better

 

[freddiemercurystwin]

You're overthinking it.

 

[^woody^]

Build it as close as you like, there are zero issues with any gap that may be formed.

 

[wyk126]

Build it as close as you like, there are zero issues with any gap that may be formed.

The builder said if leave very minimum gap, the air brick won't work so might have damp issue in the future?

 

[freddiemercurystwin]

I'm out!

 

[^woody^]

Tell the builder that if he leaves a gap smaller than the width of his head, his head wont then get shoved into it while you kick his arrse.