Tue, 09 Jun 2026 08:20:14 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130238#Comment_130238 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130238#Comment_130238 Sun, 15 Jan 2012 13:27:27 +0000 Shevek http://greenspec.co.uk/products/timber-frame-breathing-construction-external-insulation-board/pavatex-nbt-timber-frame-pavaclad-system/

On the party walls we're hoping to get the neighbour's agreement to raise the brickwork party walls (to maximise space).

Question is how should we go about insulating/cladding these party walls above the neighbour's roof line?

1. The simplest would be to leave them and insulate inside. Then we wouldn't need agreement to overhang our insulation/cladding/roof edge. But it wouldn't be the prettiest and we'd be taking a hit on thermal performance or losing a lot of space inside. **
2. The prettiest and most thermally efficient would be to externally insulate and clad with timber (actually, fire spread issue?). But here we'd need agreement to overhang the boundary and it would just be removed in the event of a loft conversion by the neighbour.
3. If fire's an issue, externally insulate and render?
4. Insulate inside and render or clad the brickwork.

** In writing this I've just realised we need to insulate inside to some extent anyway because part of our conversion will also be abutting the neighbour's uninsulated roof space... this messes up my very tight floor plans!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130242#Comment_130242 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130242#Comment_130242 Sun, 15 Jan 2012 13:45:05 +0000 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130335#Comment_130335 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130335#Comment_130335 Mon, 16 Jan 2012 13:00:26 +0000 djh https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130337#Comment_130337 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=130337#Comment_130337 Mon, 16 Jan 2012 13:19:11 +0000 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=132177#Comment_132177 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=132177#Comment_132177 Fri, 27 Jan 2012 13:54:22 +0000 Shevek
Has anyone had any experience getting permission from neighbours and externally insulating party walls for a loft conversion? If so:

1. How did you deal with the new party wall roof edge detail, did you construct it in a way that the neighbour could remove the external insulation and bear down on the party wall with their loft conversion roof in the future?

2. How did you insulate the party wall below their existing roof line, adjacent to their roof space?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=132660#Comment_132660 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=132660#Comment_132660 Mon, 30 Jan 2012 19:55:10 +0000 Shevek
I got all hooked on the idea of raising the solid brick walls and cladding them with EWI. Benefits being far more space internally, thermal mass of walls, the usual benefits of EWI and the fact that I could clad the whole building with the same material. And, from having seen some Viking House details, I was hoping to create the air barrier using plywood over silicone on roof joists and external render to the brick walls.

But when I started to draw the detail attached the problems are clear:

1. First and foremost I'll need permission from the neighbour to overhang the boundary. There's no benefit to them if I insulate externally except that I might go for a boundary wall pulled in from boundary instead of raising the party wall.

2. Rendering the wall on their side under the EWI to create my air barrier just doesn't make sense for a number of reasons. They're hardly going to agree to it and I would have little control over it in any case.

3. The render and EWI can't continue down past their roofline so I have to create the air barrier and insulate internally anyway.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133025#Comment_133025 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133025#Comment_133025 Wed, 01 Feb 2012 22:14:27 +0000 Shevek https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133175#Comment_133175 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133175#Comment_133175 Thu, 02 Feb 2012 17:41:52 +0000 Shevek ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133192#Comment_133192 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133192#Comment_133192 Thu, 02 Feb 2012 18:30:30 +0000 davidfreeborough
I would make the party wall airtight with a parge coat, make the roof airtight with a polyethylene membrane below the roof insulation, seal the polyethylene to the parge coat, build timber stud wall inside the party wall, fill voids with enough Knauf Rafter Roll 32 or similar mineral wool insulation to meet target U value & board with one or two layers of plasterboard.

If you can't afford the space occupied by the mineral wool then use Celotex, Kingspan, Xtratherm or similar PIR/PUR insulation. If this stilll isn't thin enough then get saving & use Spacetherm aerogel insulation.

David]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133260#Comment_133260 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133260#Comment_133260 Thu, 02 Feb 2012 22:34:04 +0000 Shevek
The main problem is the stair. Pushing it over to fit internal insulation would really compromise the spaces on all levels.

Aerogel is a thought. It's only the top floor and (i.e. above the neighbour's ceiling line) where we need external wall grade insulation, so we could perhaps use aerogel to the top level and then say 50 mm of mineral wool or PIR to the party wall at the lower levels. Even better it's only to the side with the stair that we really need it, so it could be quite a small amount overall.

I'd still like to insulate externally to the rear facing wall. It would mean a cold-bridge at the corner but in the long run—if the adjacent houses do the same conversion—the house would eventually be wrapped in EWI.

Thanks again, you've got me over this little hump.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133394#Comment_133394 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133394#Comment_133394 Fri, 03 Feb 2012 13:00:43 +0000 Shevek https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133413#Comment_133413 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133413#Comment_133413 Fri, 03 Feb 2012 14:10:41 +0000 davidfreeborough
As the eaves (external) wall will be behind EPS insulation, couldn't you use aerated concrete block (k=0.11) to raise the eaves wall, bond this to the party wall with wall starters & wrap the aerogel around the internal corner to limit the thermal bridge? That way you'll be able to maintain a continuous parge coat around the inside of the corner.

David]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133421#Comment_133421 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133421#Comment_133421 Fri, 03 Feb 2012 15:28:29 +0000 Shevek
We could use aerated blocks for the raised party walls as well could we not, if we render externally as shown? This way we wouldn't have to tie the two walls together. Or perhaps the acoustic performance wouldn't be sufficient?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133427#Comment_133427 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133427#Comment_133427 Fri, 03 Feb 2012 16:14:49 +0000 Shevek https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133432#Comment_133432 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133432#Comment_133432 Fri, 03 Feb 2012 16:28:04 +0000 davidfreeborough
David]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133725#Comment_133725 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=133725#Comment_133725 Sun, 05 Feb 2012 14:49:36 +0000 Shevek
I'm in two minds about where to put the air barrier in the roof. I've shown it above the plasterboard but I'd like to take the internal render coat on the wall all the way up the wall to the underside of the plywood deck, so perhaps I should move my air barrier to the top of joists too? Perhaps with silicone between joists and plywood?

The other thing I'm not sure about is the Roofkrete, which appears to need its own polythene sheet. What are the green options out there for flat roof waterproofing, anything breathable? Also, I haven't quite got my head around how the neighbour would deal with the waterproofing when they want to add their own loft conversion. Any thoughts of that from the builders?

I think taking the OSB board all the way across the wall may not comply with fire regs too...]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=134573#Comment_134573 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=134573#Comment_134573 Thu, 09 Feb 2012 18:30:31 +0000 Shevek https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=134587#Comment_134587 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=134587#Comment_134587 Thu, 09 Feb 2012 20:51:13 +0000 Shevek https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=150500#Comment_150500 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=150500#Comment_150500 Wed, 04 Jul 2012 17:43:56 +0100 Shevek
No flush dormer because planners deemed it too bulky. And no raised party walls because the structural engineer says its too heavy for the foundations we have.

So the question is what to clad the dormer in? My first thought is to continue using rendered EWI and infill studs with mineral wool as well. What do you think?

Most other houses around the neighbourhood have used wall tiles but they look ugly as sin.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=150534#Comment_150534 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8424&Focus=150534#Comment_150534 Wed, 04 Jul 2012 22:44:29 +0100 Timber