Redbeard

I have used 21 Degrees (formerly Green Building Store). 21 Degrees seems to be a big network, so it's their Huddersfield office you are looking for - Chris Herring and Bill Butcher have been my contact-people.

When you say the soakaway is > 5m from your boundary I think you mean the front one. Having seen your latest pic I'd guess your house to be about 5-5.5m wide (?) and I believe the required distance from boundaries to be 2.5m minimum, so depending on the surface area of the soakaway, if my estimate is anywhere near right, you could be close to the limit side-to-side. In any case I doubt anyone is going to quibble unless your neighbour objected anyway. You say: But if you used my 'grating' idea you could keep the level well below the DPC, keep the aco drain at the bottom of the 'trench' and still lead any water away to the soakaway.

Thanks! Good! Not least as it suggests the contractor is on the ball re guidance - except perhaps for the level at the house. It's difficult, isn't it? We all know BC recommend 150mm below DPC, and ditto that no-one told the rain in many areas that it should only splash up 150. But we also know we need not to fall into a trench as we open our front door! If it were me and I wasn't ever intending to wear stilettos (and nor were any of my potential visitors) I think I would do the drain much lower, with a 'boot-scraper'-type grating over the top at the desired 'pedestrian level'.

5m from my boundary And at least the same from any buildings (incl your own)?

How far is the soakaway from the boundary, and from your building and any neighbouring buildings?

AFAIK Type 1 'MOT' has lots of fines in and can almost set like concrete. It is not what you want for a permeable base. My contractors used 300-500 40mm limestone with a permeable membrane over, then 'permeable block paviours' (which have an extra gap formed by nobs on the sides) with large (3mm-sh) grit in the resultant gaps. It performs excellently, although the natural ground below the limestone is clay and bedrock. If I sling a bucket of water onto the paving it just goes *slurp* and it has gone. Try putting "can MOT type 1 form a permeable base?" into a search engine, though, and you will get the whole spectrum, from yes, very much so to 'no, it is impermeable'. My experience suggests that the latter is the safest one to believe. Others' experience might be different... And as for the advice re a French drain, 'to direct the water away from the house wall', it has to have a destination. What is it? Is it a soakaway? If so is it the requisite distance from buildings and boundaries?

I wouldn't put any concrete against the wall. It gives you a joint which will crack and open and let moisture in. Membrane and gravel and, if you have somewhere for the water to drain to, perforated pipe in the bottom of the trench - although it doesn't really seem deep enough to count as a trench, or perhaps the pic is misleading. How deep is it?

But no point. The joists themselves are the thermal weakness. Agree if you just 'posted' deeper WF to hang below the joists, leaving the joist bottoms 'naked', but my hope is that there is sufficient crawl space for a cross-layer of rigid WF underneath (or flexi WF in a form of 'Larsen Truss' (spaced joist, @ChurchAl, if you haven't come across the term before)). That way the thermal bridge is mitigated.

Is it single-storey?

Agreed. How much clearance/crawl-space do you have below the joists? If you can 'underdraw' with further insulation then you can also 'cloak' the thermal bridge of the joists. I'd go for as close to 300 as you can. Although the temp differential between room temp and 'outside' (under-floor) may be only 21 or so at 0 degrees external, the temp diff between the flow and the ext temp will likely be a minimum of 40.

Sorry I am the first to chime in. I think you need a Structural Engineer and an 'invasive survey' (expose enough of the lintel to see exactly what it is so the SE can calculate - not guess.) My (definitely non-SE) feeling would be that whatever dead load that lintel is designed for it was not designed for the live load you refer to.

It is hard to tell, but the base coat looks much too rough in parts for a 1.5 'gritty-coat' to 'hide'. The 'tramlines' simply should not be there. A little off-flat, maybe; tramlines, no. They should have been sponged out when the render was stiff but still 'moveable'. Of course we have not seen the whole surface but (assuming everything is now hard as a hard thing) the 'tramline bit' needs another coat, in my view.

Is there a nuance here in relation to the 'after completion PD'? @kandgmitchell rightly point out that your 'during works' use seems to be covered 'for the duration of operations ...' . Then it becomes 'un-PD', but would be PD after completion if you erected it again! If the Planners notice I wonder if they could require you to take it down in order to re-erect it?

I m a little confused by the first few posts. Isn't the easiest way (to find out whether the potential extra space exists) to take off the architraves and measure the masonry opening? If you want to be truly 'belt-and-braces' you could hack a little plaster off on both sides above the door to see by how much the lintel bears on the masonry each side. This would give you an idea of whether, in extremis, you could widen out the masonry opening without risk - a not inconsiderable task, BTW. Find the dimensions of your composite door *and frame* and if that dim is smaller than the masonry opening you are set to go. If not, you're not.

I think moss gets so much less of a 'key' on clay than concrete, particularly when the concrete is deteriorating. I wonder if you will have an issue at all.

Beware air movement in the cavity. I had mine insulated with 'bonded' (ha!) EPS beads to a questionable standard as we had found really significant air movement in the cavity when doing minor works prior to EWI. I am not convinced we 'got it' 100%, but the EWI would have been incredibly expensive external wallpaper if we'd not addressed the cavity issue. As @Mr Punter said yours does not look a promising front elev for EWI with the oriel, bays and porch. I worry about the standards on 'down-to-a-price' work, and I would want drawings of how they would address the bays etc. I have seen some aesthetically dreadful 'solutions' and none which avoided serious thermal deficiencies except where the contractor had removed the bay windows, resin-anchored threaded rod in and fitted new bays on top of the EWI. Very nerve-wracking till they are on and right, I would guess.

Have you had a structural engineer's report? You could argue that this quote means that you are not covered., but this covers damage to floors, and refers to external walls. You have an issue with *walls*, not floors! If you have not had an SE report do get one, and ask the insurers to tell you why they *won't* pay out.

They normally sit inside a socket on WBS but at the bottom of the socket on mine is a 'stop', so little chance of smoke. Like I have never had any).

Why not do it in an insulated plaster such as Diathonite? That way there is no separate insulation and plaster layer. If your proposed nIWI is PIR then Diathonite will not give you as much insulation value, but at least every bit is insulating, unlike a system with battens and plasterboards. PIR thermal conductivity 0.022W/mK and Diathonite around 0.039 IIRC.

I am not thinking of the floors putting pressure on the walls, but whether the change in floor structure in any way 'undermined' the internal walls. As it was suspended floors before that does not seem likely, as each wall would have its own foundation. As I asked above, what ('footings') foundations did the internal walls have?

Ooh err... How long had you had the house before you had the UFH? What were the floors before? What footings did the internal walls sit on? If you were in the house for a while before you had the UFH done it suggests some 'parameter' has been (inadvertently) changed.

Welcome, Until I read your last line I had a couple of thoughts as to what you might do, but the fact that you have already got 37.5mm board on (and for clarification, that's 25mm PIR, isn't it?) could weaken your bargaining position. The one experience I had with trying to argue the 'not-a-15-year payback' thing was that BCO insisted on a SAP assessment which, even 17 years ago, was not cheap. In that particular case it was complicated much further by the SAP assessor managing to 'prove' that it *would* give a 15-year payback (it wouldn't), leaving us with no option but to increase the depth of insulation! As regards the party wall, whether you can make the 'it's free heat from next-door' argument (and whether they can too!) may depend on the BCO's opinion. On the other hand it is not an external wall so I would ask the BCO to point out the specific section of the regs which requires party walls to be insulated as per external walls. As a 'negotiating stance' you may be minded to offer 'cloaking of a potential bridge' by returning the IWI onto the party wall for, say, 1m at each return. That will help your heat-loss a bit. Don't forget to cut back the plasterboard off the external wall IWI otherwise you have just built in another, albeit smaller, thermal bridge.

EPDM grommets

Yes, it probably would - an interesting thought to those who don't want to use trickle vents. More expensive, though, and one more 'moving part' (another - PIV - fan). (And come to think of it, surely one of the 'advantages' suggested for PIV is that you can just sit it in the loft, blow down onto the landing and then it finds the gaps on the gr floor? If you need to duct to dry rooms you may be getting as 'complicated' (in the eye of some 'beholders') as MVHR).

Are you sure it is not condensation? Hypothesis: Cold wall, cold (impervious) membrane - condensation on membrane; droplets run down and permeate both the surface of the concrete and 'pool' within the depth of the slab where the membrane has pulled away.