low_and_there Posted August 17, 2023 Share Posted August 17, 2023 (edited) After an earlier agreement to build on to the party wall that our neighbour built 5 years ago (before we bought the house), things have gone sour and we've decided to build a standalone wall on our side to avoid the Party Wall Act (PWA) process entirely. Looking for opinions/experience/ideas on how to weatherproof the exterior of the wall we'll build when the gap left will be very small. I know that it is not good practice to leave a gap too small to maintain but I'm afraid we will be doing just that because it's a narrow mid terrace - 4.6m wide. I am looking at leaving around a 50mm gap. Obviously I don't want to create problems for the future so keen to understand just what those problems might be and how we might mitigate them - for example, to stop debris falling in, presumably we can use some mesh; to stop water pooling, we can ensure water is directed away and if it does collect there, we can perhaps have some kind of tilted fillet at the base to ensure water is directed away can be directed away. This whole approach was suggested by Building Control, who have indicated that they'd be happy with Raft Foundations instead of traditional trench ones (meaning we don't trigger the PWA), and Fireboard (9mm Magply) on the external face of a Timber Frame structure. As such, what I'm thinking is that we construct the external wall lying down, with the Magply board attached, and then lift it into position. Constructive suggestions on alternatives or ideas on what issues we may run into would be appreciated. (And yes, we have really really tried to resolve the Party Wall issue with the neighbour but it has reached an impasse.) Edited August 17, 2023 by low_and_there clarification Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted August 17, 2023 Share Posted August 17, 2023 Looking on their website it says it can be exposed for minimum 3 months, i'm guessing that should read maximum. It'll need rendering in that case. What is their disagreement? Do you not want to go down the PW Dispute route? Link to comment Share on other sites More sharing options...
markc Posted August 17, 2023 Share Posted August 17, 2023 Assuming the relationship has gone past mediation, how about building upto the wall but not onto it. Treat it like a cavity, drainage channel at the bottom, compressible insulation etc. between the two walls to prevent debris etc. getting in. Your neighbour could complain saying you have stopped them accessing their wall but they built to the boundary. Yes everyone wants to build as big as possible but building upto a boundary rarely ends well. Link to comment Share on other sites More sharing options...
low_and_there Posted August 17, 2023 Author Share Posted August 17, 2023 1 hour ago, MikeGrahamT21 said: Looking on their website it says it can be exposed for minimum 3 months, i'm guessing that should read maximum. It'll need rendering in that case. @MikeGrahamT21 I will go back to them to clarify because I spoke to them and they indicated it can be left exposed. Any thoughts on a suitable thin alternative weatherproof finish there? Perhaps metal... @markc To clarify, our neighbour has built past the boundary - i.e. it's a Party Wall. That sits astride the boundary. When you say 'drainage channel' at the bottom - what kind of thing are you thinking? Like a ACO drain or some kind of custom formed floor gutter made of lead or something? Link to comment Share on other sites More sharing options...
ETC Posted August 17, 2023 Share Posted August 17, 2023 (edited) New cavity wall with facing brick outer leaf and an ACO drain down the "gap". Mono-pitched roof (high part of roof to party wall). Edited August 17, 2023 by ETC 1 Link to comment Share on other sites More sharing options...
low_and_there Posted August 17, 2023 Author Share Posted August 17, 2023 14 minutes ago, ETC said: New cavity wall with facing brick outer leaf and an ACO drain down the "gap". Mono-pitched roof (high part of roof to party wall). What do you see as the benefit of a brick outer leaf? Weatherproofing? Longevity over a timber structure? Thanks Link to comment Share on other sites More sharing options...
ETC Posted August 17, 2023 Share Posted August 17, 2023 What are you building? Link to comment Share on other sites More sharing options...
low_and_there Posted August 17, 2023 Author Share Posted August 17, 2023 @ETC a kitchen (extension) Link to comment Share on other sites More sharing options...
markc Posted August 17, 2023 Share Posted August 17, 2023 Agree with @ETC you will not be able to get back to this outer/cavity wall so it needs to be bullet proof, doesn’t need to be pretty as no one will see it, if timber frame how would you flash the bottom? Likelihood of any water in the cavity tracking back under the timber sole plate. Link to comment Share on other sites More sharing options...
ETC Posted August 17, 2023 Share Posted August 17, 2023 (edited) 41 minutes ago, low_and_there said: @ETC a kitchen (extension) Build that wall (or all the walls) in cavity wall construction with an outer leaf of brickwork - the brickies can build this wall overhand. You will only be able to place the outer edge of the foundation for your wall next to the foundation for the party wall. I am assuming that the party wall will have a (strip) foundation with a projection of at least 150mm - your (strip) foundation will also have a projection of about 150mm. This could mean that the outside of your new external wall could be located about 300mm from the party wall. There are other ways to do the foundation but if you need to stay away from the party wall you will also need to stay away from any foundation. Put an ACO drain in the gap. Unfortunately if leaves get into the gap you will need a long stick! Edited August 17, 2023 by ETC Link to comment Share on other sites More sharing options...
Mr Punter Posted August 17, 2023 Share Posted August 17, 2023 If it is a party wall you have a right to enclose it on your side and use the party wall as part of your structure. Yes, may need to serve notices if you need to cut into the wall or raise the height, but check very carefully that this is the case before you serve the notices as once the process begins it is difficult to stop. You could suggest a sweetener to the neighbour, such as cash payment, should they consent to the works in the notice. They will also need to be satisfied that the works are fully insured. Link to comment Share on other sites More sharing options...
low_and_there Posted August 17, 2023 Author Share Posted August 17, 2023 48 minutes ago, ETC said: I am assuming that the party wall will have a (strip) foundation with a projection of at least 150mm - your (strip) foundation will also have a projection of about 150mm. This could mean that the outside of your new external wall could be located about 300mm from the party wall. The neighbour's house is about 50cm lower than ours (the road is on a hill). Looking at the SE's drawings for the Party Wall build (our neighbour shared them with us when we were on good terms) the strip foundation they have put in does not extend at all on our side (excepting that it is obviously underneath the party wall itself. If the houses were level with one another then your point would be valid and present a problem, but it seems that the foundations don't project... That is actually a bit weird isn't it! Instead of strip foundations we're going for 'raft' foundations (as mentioned in OP), so no need to project 150mm. Link to comment Share on other sites More sharing options...
Temp Posted August 17, 2023 Share Posted August 17, 2023 Before you start building walls work out how big the roof overhang or any gutters as that may dictate how big the gap is. If its a flat cold roof construction think about how the void will be ventilated. Sometimes one orientation for the rafters is better than the other for this because it moves where the vents will be. Link to comment Share on other sites More sharing options...
ETC Posted August 17, 2023 Share Posted August 17, 2023 Don’t build a cold flat roof. 2 Link to comment Share on other sites More sharing options...
Big Jimbo Posted August 17, 2023 Share Posted August 17, 2023 If the neighbours house is 50cm lower than yours than your damp course is going to be about 500mm higher than his ? If thats the case when all the crap fills the hole between your houses, his is going to get damp a long time before yours.😁. As @Mr Punter has said. If its a party wall you have a right to build off it, even if he does not like the idea. Check that out before you go further. Link to comment Share on other sites More sharing options...
Tetrarch Posted August 18, 2023 Share Posted August 18, 2023 If it's a party wall, then surely you have the right to hang guttering above the PW. This would serve as protection from the rain and as the gap is also yours you can do what you like to cover it as long as you don't touch the wall itself. I'd have thought that putting some kind of sealant on your bl~~~y wall would be difficult to effectively enforce legally Regards Tet Link to comment Share on other sites More sharing options...
low_and_there Posted August 18, 2023 Author Share Posted August 18, 2023 6 hours ago, Tetrarch said: If it's a party wall, then surely you have the right to hang guttering above the PW. This would serve as protection from the rain and as the gap is also yours you can do what you like to cover it as long as you don't touch the wall itself. Yes this is a good point! Thanks Link to comment Share on other sites More sharing options...
low_and_there Posted August 18, 2023 Author Share Posted August 18, 2023 6 hours ago, Tetrarch said: I'd have thought that putting some kind of sealant on your bl~~~y wall would be difficult to effectively enforce legally what kind of sealant are you thinking @Tetrarch? Thanks Link to comment Share on other sites More sharing options...
Tetrarch Posted August 19, 2023 Share Posted August 19, 2023 22 hours ago, low_and_there said: what kind of sealant are you thinking @Tetrarch? Thanks Something like this: https://www.screwfix.com/p/no-nonsense-roof-gutter-sealant-black-310ml/67521 Regards Tet Link to comment Share on other sites More sharing options...
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