celotex thicker than 100mm for cavity wall?

[biff]

 nothing has seen so many changes down through the years as the return on the reveals in cavity wall building,
         origionally we were asked to use a vertical 4" dpc up the back of the brickwork and then return our blockwork to butt into the dpc,keeping it in place while strengthing the opening to assist in fixing the frames,
      then things changed,there was a period of just two skins coming to the end of the reveal and the cavity was blocked up later as the frames were being fixed to noggins, this proved to be disasterous because the nogging worked loose damaging the brickwork and bringing in the draughts.
   then the returns came back into action using a thin, fillet of poly to act as a  thermal barrier behind the vertical dpc,the dpc was also widened to 6" ,this was a massive improvment,
      then the reveals were returned to butt up to 25mm of blue kingspan 100mm fillet,this is more or less where things sit at the present.
   here in ireland 2 layers of cavity batts would not be allowed, it would have to be sliverbacked kingspan, this has been the rules here for the last 15 years or so. wooden clills are not allowed,it is all concrete prestressed with a seperate dpc underneath it and coming up the back of it.
   i would be very suspicious wookey of any inspector who told you that this was the most complicated building he had ever seen. my advice to you,,
 is to play along with it, keep your money tight in your roll,any little changes in the plan,query them, and if you are not sure, get a second opinion, you will always be greeted with a smile and a welcome while you still have the money.its a bit different when its gone,
                                                                                                                     biff

[wookey]

I picked the building inspector, not the the builder, so it'd be surprising if they had a deal. The complicated bit is the roof, not this admittedly unexciting (but better than typical cavity). The reveal is not returned because returned brick reveals are a terrible thermal bridge so I'm using ply boxing as on the denby dale passivehouse design (actually it might be trespa or fibreglass boxing if I can stomach the cost). That corner is a 53 degree angle just to keep everyone on their toes.
What's not green about a 200mm cavity with dritherm (recycled bottles) fluff, low-conductivity teplo ties, thermal bridges removed and thus a U of 0.16? OK it's not timber frame or strawbale, but it's attached to a conventional house so something too different would be problematic.

Here's some roof:

[biff]

hi wookey,
           the devil is in the detail and there is no suggestion of the inspector doing a deal with the builder,but they are pals and if an inspector has to revisit a site upteen times because of shoddy work it makes their life miserable so they like builders who play the game, quite often when a builder is coming under pressure from a client over the "devil in the detail",it make the inspectors life a bit easier to reassure the client that the builder is a fine fellow",progress is slow im afraid but the quality if fine".the last thing they want is for you to be on the phone every five minutes asking "come up here now and see if its ok"
    the roof is not really complicated,it is just that you have to work between two existing buildings a fuel sore on the right and the existing house on the left,.the fact that the fuel store is running off at an agle makes it a bit akward, the elevation facing the camera was designed to suit the 2 reversable doglegs angled at 130 degree,s. thats normal enough, very common on conservatories,it is also a good way to disguise the fact that the fuel store is not in line with the house., from what i see of the roof,it is being set out to take zinc cladding,,not so common but it means you can avoid the drastic cutting if you decided to use slate or tiles.at the moment it sems that you have two pitched roofs and a bit running onto a flat roof.might i suggest that you save yourself a lot of pain and hardship by using an esso butyl sheet (pond liner)on the flat and taking it up under the pitches on every side. the butyl works well round corners  and inverted corners,its for the job.lay kingspan on it,weighed down with 50mm of clean pebbles.
 returning to the reveals(excuse the pun) ,a fillet of kingspan blue or better again pink makes an exellent thermal barrier,it runs up behind the dpc,100mm wide and 25mmthick, which means the returning blockwork will be 265mm with 10 mm joint assuming the wall is 300ww wide.this would add strength to the wall to support the frames.i wish you luck with your building project, be pleasent but firm with your builder.watch out for that horrid thing called "chargable extra"
                         biff

[wookey]

Not butyl, but sika sarnafil, which amounts to the same thing. (I actually specified EPDM, but the roofing company chosen do the sika system). No zinc - that's next door - the pitched parts will be tiled. Here's inside as well.

[desperate]

Nice looking project there Wookey, it's good to see things actually taking shape after all the planning and working on the details, it looks like you are adding a significant area to the original building in a somewhat unconventional style, did you have any problems with PP?

all the best

Desp

PS sorry Acresswell, just noticed it's your thread I've just tresspassed.

[acresswell]

No problem     I've been interested in the extra details...

please feel free to carry on!

Adrian

[Ivan]

Last year, we fitted two layers on the inside wall, under plasterboard. We used bonding compound to stick plaster board, and to stick the insulation top sheet to the lower sheet. It sticks pretty well, even to the ali foil surface.