bissoejosh

Sadly not, I couldn't make the budget work on this occasion so using mineral wool.

Agreed, I think this stays as it is. It may be the case that the Vapourblock is also sufficient for racking strength which makes the external sheathing rather redundant except for holding insulation in place and providing protection during construction.

Another option, although the frame is drawn to allow for the 12mm internal board and changing now would be a bit of a pain. Panelvent instead of the Egger looks interesting - same sort of product just a little thinner and hopefully cheaper?

Hoping to use the VapourBlock OSB as our airtight layer and VCL for durability and ease of construction. Service cavity is currently 25mm directly behind PB. I thought minimum external vent was 25mm - BCO upped it to 38mm. I could up it to 50mm if necessary?

Currently our design is based on using 15mm Egger DHF for our external sheathing but having received some prices it seems an expensive option. Any huge issues (assuming the engineer OK's it) switching to either 11mm or 15mm OSB? I'm sure others have used OSB and it comes in at roughly half the price so a substantial saving on 300m2. My only thought was weatherproofing during construction as I know the Egger is pretty water resistant. For reference the rest of the make up as follows: PB & Skim Service Cavity 12mm VapourBlock OSB (again quite an expensive option) 245mm i-Stud 15mm Egger 38mm Cavity 20mm Cladding Many thanks

Is the outer sole plate likely to be at risk sitting directly on a cold block/brick? I really like @JSHarris idea of sticking with beam and block but working around the regs if possible. I've never understood the need for a concrete beam to have ventilation when a slab is fine without. If BC insist (ours have) how about keeping a void beneath but fitting additional insulation directly to the underside of the beams? No idea how this could be done though - glue of some sort I'd guess...

As discussed previously we're doing something very similar to your detail. I'd question the benefit of the marmox block on the inner skin, if you carry the cavity insulation down far enough it makes it almost redundant and as I'm sure you know it isn't cheap... Have you got enough depth on the outside face to carry insulation over the sole plate and down the outside edge of blockwork? I don't see a problem with the b&b floor depth as long as it's vented but would be tempted to bring the ffl up to just above ground level if not to allow even more insulation depending on the site levels.

To round this up... Engineer did worst case point load calc with data taken direct from Norbord. Huge margin of safety in the end. BCO happy and thanked me for providing the extra detail. Happy days.

In that case I'd do a variation on the touchwood method... http://www.touchwoodhomes.co.uk/index.php/foundation-systems/53-strip-foundations Basically a cavity foundation with the beam and block set as low as you can. Slab of insulation above this and carry the cavity insulation right up to sole plate if possible. If we upsized to a 300mm stud I'd have done exactly the same as the diagram but you can modify it support your brick outer leaf which we don't have.

I had the same question and have decided to do the following... Our frame is quite wide at 245mm so we're splitting our sole plate into 2x95mm plates and insulating the gap between to minimize the primary bridge through solid timber. In addition to this we're using insulation on the external face of our block-work upstand which basically sandwiches it between this and the internal insulation. Hopefully this should help reduce the risk of condensation build up which to be honest was my larger concern than the cold bridge. How wide is your wall?

Apologies, I'd tried the ARUP link previously but couldn't get it to work on my mac hence asking. Seems to be working this time.

Fairly certain this has been covered before but can anyone tell me how to calculate decrement delay? I've seen the link to the calculator by Arup but I think it's windows only. Thanks

Thanks, out of interest are you going for a concealed gutter look like the pics above?

I'm considering corrugated (depending on swmbo) for our roof as an alternative to Tata standing seam. Have you found a supplier for residential use who provide a working detail?

Thanks, I've already done this and will see where it leads. Was really wondering if anyone had any direct experience in the region, a recommendation is always preferable where possible.

Does anyone have any recommended suppliers for cellulose insulation in the South West? We're based in Cornwall and I'm keen to get a cost comparison compared to our proposed solution. The idea of the insulation being done in a day or two is very appealing... Thanks

A while ago I found the detail(s) shown below. These might help @Rdddk ? - Does anyone have any views on their pros/cons? I'm not too sure on the detailing for the air-guard as shown which looks like it would be fiddly . I'd had planned to simply wrap the airtight membrane around the joist end before tucking back in to the wet plaster coat below. Thanks as always

We're doing something similar building over a full filled cavity wall 400mm thick. Above this is a 245mm i-Beam frame. With the help of the posi suppliers I had planned to run the joists right out across the top to flush with the outer skin and then build off this - much like a timber frame deck construction. Wondering if some of the potential issues might also apply to us so keen to hear other responses. My understanding was that as our cavity is full filled and the space between joists the same then we're limiting any risk - happy to be told otherwise before it's actually built though! Our BCO hasn't flagged anything either at the design stage...

We're going with an i-beam frame, all designed by CTD to be stick assembled on site from factory cut timber - hopefully much like a giant air-fix kit. I looked at Larsen but couldn't find a supply only provider. As mentioned CTD are refreshing to work with compared to many others and I feel they could tackle virtually any frame design issues.

thanks everyone, all very useful. Certainly looks like I can make it work and a little more investigation into the homemade manifold/silencers is in order.

sounds like a possibility headroom permitting. Are they MVHR specific mounts or ones that had just happen to do the job? I've seen a few suggestions of hanging from bungee but longevity sounds an issue.

is that the highest element in the system or is something taller out of shot? We have limited headroom in our proposed space but this looks like it would work fine assuming nothing taller out of sight.

Just seen this thread, very useful as I'm currently going through the same MVHR location decision process. Can I ask if anyone has installed their MVHR either above or next to a bedroom and is the noise intrusive? Of our two location choices option1 is in an attic space created above our bedroom en-suite. The rest of the house has vaulted ceilings but we've dropped it here for storage or potentially MVHR. If I can sound proof it adequately from the bedroom it would be my first choice leaving more room in option2 for plumbing/HW cylinder which would be very useful. BPC have provisionally quoted for an Xpelair Natural Air 180 to give an idea of unit size. Thanks

Ha, no I think not. He has honestly been great throughout & genuinely hasn't seen it done 'that way' before hence the questions.

The joists are all at 400mm, with a 22mm deck specified so pretty belt and braces. No mention from the BCO about wall/joist direction just about the P5 being crushed in general from the loading. The frame guys have gone to the engineer now to get him to calc and sign it all off. Hopefully this will prove satisfactory as evidence for BC and we can move on.