Posted By: Peter_in_HungaryThe typical EWI (EPS wit thin film render) will not wick moisture through to the bricks.

And that has a revolutionary (i.e. contrary to conventional wisdom) benefit: as EWI of EPS (at least - maybe other plastic insulations too) has near-zero capillarity, it alone satisfies the Requirements of Bldg Regs C 5.2.a. to d. (liquid water protection), so deemed-to-satisfy C 5.5.b. (DPC to be 150 above GL) is no longer necessary. That '150 above' is universally accepted as 'common sense' but in newbuild (or extension/alteration) with masonry foundation wall and stud upper wall EWI'd, its omission is very beneficial, as the wall studwork/insulation can link up with the under-screed floor insulation without the classic thermal bridge problem.

Sorry - this is a diversion, not as the OP's question. Maybe I'll start a new thread, and publish the whole documentation I recently submitted for BldgRegs (and got accepted, tho not sure the plan-checker actually took it all in!). It covers not just the above, but the whole 3-way junction of a thin 100thk block found wall, insulation-under-screed floor slab, and EWI'd stud upper wall (which has been my own favoured way of wall building - also Viking House's (PH prefabricator), if you remember his contributions back in the day) and the omission of any VCL at all in the wall (WUFI proved).

This 3-way junction has been a perpetual thermal-bridge problem for eco-builders, with various kludgy solutions, to which the fundamental answer has been a reinf conc raft floating over continuous underfloor insulation (which couples fairly seamlessly with wall insulation).

This I agree is the ideal solution, but not structurally suitable for an attenuated floor plan, especially in extension/alteration. The alternative above (frequently disputed by Bldg Insps, hence the effort to get it fully argued, documented and approved once and for all), is to properly solve the thermal bridge problem in the 'conventional' (and highly adaptable to extension/alteration) conc strip/masonry found wall design.

Hi Tom,

I'd also be interested in seeing this. I'm just working through a similar build-up for my garage build which I know will be a struggle to argue with BC but would make installation easier and more robust.

djh, sgt_woulds - as soon as I have time!

sgt_woulds, I think B-s1,d0 is a spread-of-flame grade, not fire resistance. Yes, I'd like to know that too.

Semi true I think. It takes quite an effort to get a straw bale fire going!

An 'ordinary' straw bale on its own burns due to the large 'fluffy' surface area but you need to sustain the ignition source for quite a while before it takes hold on its own.

A stack of straw bales takes longer still and the centre bales usually survive.

A straw bale wall has less surface area and tends to be more densely packed. It will probably take 2 hours to burn through from one side even without the render.

From memory, Ecocon straw sips have an REI 120 rating I think?

For exernal wall fire regs, you need to read Building Regs B4 Sections 10 and 11. There is a lot of detail, and takes a few re-readings to catch it all. Section 10 is fire spread on the outside of the building. Section 11 is fire spread to neighbours.

They don't contradict, but have subtle differences. For example, there are some cladding products that would be ok in terms of spread to neighbouring buildings, but not meet spread on the outside of the building. Eg. cladding on a stone or block wall, where the stone/block gives the "neighbour" protection. What's under the cladding can impact it's suitability or not.

Distance from the boundary greatly impacts the requirements, as do openings or "unprotected" areas. Up to and including 1m from boundary is one level. Beyond 1m is a different level, and the area allowable which is not protected increases with distance.

Read those two sections carefully (plus related sections, eg. fire spread on roofs). Be wary of product manufacturers "summaries" of the regs. For Scotland, the regs are almost identical, though a few bits are slightly stricter (Section 2.6 and 2.7)

Hello again! Well it took me a while to investigate the damp and I'm now sure it's not a leak. I tried the cling film on wall technique and it didn't show much moisture in the morning on the actual cling film, which did make me wonder what was going on. But then I mentioned it to my neighbour and she confirmed she has damp in the same place in her house. They are detached houses built around 1910 and each house is a few feet further forward than the last one along our road. The corner where the damp is in both our houses is where the north and west facing walls meet and that corner in each case is further forward than the next door house so she thinks it's something to do with wind/airflow coming up the street and hitting the same corner of the building on each of the 5 houses.

Does this sound convincing? And, if so, I assume good EWI would help with this.