Redbeard

In terms of changing the appearance, yes it does. In terms of damaging the property, yes it can. In terms of damaging all properties to which it is applied, no it doesn't. Like all insulation measures it needs care and risk analyses. My guideline is that the end result must not look stupid. If it does, it probably is, and there are probably several more stupidities thrown into the mix. 'Cowboys' never give any discipline a good reputation, but there are good guys out there. I just feel sorry for those who get not-a-good-guy.

Do the circumstances require it to be a permeable sub-base? If so I am not sure MOT will cut the mustard (others on here know more than I). I used between 200 and 400 c40mm crushed limestone, membrane, and finer limestone (but not sand or MOT) as a bedding layer.

... and presumably levy a new charge on you. Would LABC give you anything back? (I don't expect a positive answer!) I am not sure I would actually know where my LA's BC dept 'hung out', and I'd think it v unlikely now that I could actually go and see them. Everything I have done with them for years is by phone or e-mail, apart from visits.

Which ones? I suspect 'put boards' should read PIR boards.

I am not clear what the issue is. Is this a house which you lived in before the works, which has a proven record of noise transfer issues from GF to FF and vice versa? If so do you get the impression it is (a)impact noise which is the main one, or (b)airborne noise. If the former I would not necessarily expect a big change, as much of the 'noise' could be transmitted through the structure via joist pockets. If the latter it may help. If there was not much of a problem anyway why bother? (Unless you are using the insulation for both sound and heat *and* you want to 'thermally compartmentalise' the house).

As you say the front looks difficult for EWI with the incoming power-lines. How would you deal with them? Lots of Red Tape there, I guess. Step-cracks above front GF window (are you happy the original problem has been solved before you 'box it up'?), questionable boundary (? - your porch roof seems to meet a line down from next-door's FF window cill, so is that the boundary?) Where, then, does the fall-pipe go once you have EWI'd? I think your idea to IWI may be less fraught. However if you were to EWI the front... If there is no soffit and you think it would look daft to extend your roof-line only, how do you deal with the EWI projection? 'Industry Standard Capping Details' (bits of bent alu gunged in silicone) have a limited life, particularly if they are of the 'downstand' variety. Measure carefully, outside and in, the height above the window. It is not unknown for EWI to stop before it reaches the height of the ceiling inside, in which case what do you do? If that were left 'un-treated' you could face a strip of mould at the top of the room. Internal 'downstands' can be done. Bring it down well below the line of the top of the EWI. I am probably not alone on here in not regarding 300mm as a huge lot for the loft. Assuming you are not storing stuff in there, and that you are using 'cheap stuff', why not use 400, or even 500mm? You'll only do it once. If you do that you'll probably find the biggest 'shortcoming' is then at the hatch. It's difficult to leave yourself a way in *and* achieve excellent insulation coverage and air-tightness. Get inventive!! I worry about the plan to IWI the gable wall in the garage, certainly at 100mm - with a lot of PIR on a wall giving onto soil. If you look at a Glaser-method condensation risk assessment for PIR (which you can get for free on many manuf'rs' web-sites), and the manufacturer's advice, you'll see that they require you to keep the 'outward path' vapour-open (by removing impermeable treatments inside and/or outside). That's because the VCL on the inside (if indeed it is functioning as a 100% effective VCL) blocks the possibility of any retained moisture in the wall coming back in. As far as I can see, if you block the path inwards, you have no moisture-loss path at all. I may be wrong, though. Enlightenment welcomed! I've written a lot. I hope it is useful - it is certainly meant to be. A lot of 'thinking-through' to do, I reckon. Do come back with Q's and comments. Perhaps ask Nottingham Energy Partnership (0115 985 9057) if they can recommend an assessor. A retrofit assessor course may well increase your knowledge level (of course I don't know how much you already know) but it will not necessarily (AFAIK) give you access to a measured survey model and software, so while it may help you to make a judgement it will not allow you to spit out 'numbers' - running costs, kWh p.a. etc). You can, of course, do that 'long-hand' if you have time, and I bet there are some free access models out there somewhere. Edit: Re EWI - do not automatically think you cannot go below DPC. You do have to think it out carefully and perhaps use different materials but it can be done - down into a French Drain. Caveats re where does the drain exit, have you just dug below the footings, etc., but with care it can be at least considered. I see countless examples where the EWI Co has dutifully avoided bridging the injected DPC which is 150mm at least above internal GFL - leaving a cold bit just behind the 120-year-old skirting...

Hi @Julestools. I don't know what mix was used. That was before my involvement. I am not a lime expert but I think I share your idea that something as rich as 1:2 or even approaching 1:1 might be required. I don't know if having it that rich has any downsides. (Come to think of it I have used lime putty when I want a really creamy mix. Could you do that?). Out of nosiness I note that you are proposing mechanical fix only. I take it this is probably onto existing gypsum plaster. Others (including specialist merchants) disagree, but having gypsum in a 'sandwich' always makes me a bit uncomfortable. I usually strip that off and do a lime parge coat, but then maybe I like making work for myself!!

Hi @flanagaj, I tried to send a private message, but I gather you cannot receive them. Have you intentionally disabled the PM function, or has it just disappeared and is this an issue for Forum mgt?

... and I was just about to write that too. PIR externally amounts, in my view, to a VCL on the wrong side of the 'sandwich' - and I wince every time I see a TV show depicting it. How about rigid wood-fibre with a scratch-coat of lime render before the battens and (?hit-and-miss?) larch?

I know someone who tried to use NHL for the same 'economy' reasons. I think the main problem was using it as the 'adhesive coat' behind the boards. As I recall it simply did not stick at all - not even the 'light tack' afforded by RK70. I don't think he ever tried it on the boards, since he had to buy RK70 for the 'adhesive' coat anyway. Particularly if you are doing it yourself and have not done a lot of plastering I'd recommend RK70. It is so 'forgiving'. Slow, in colder weather, but relatively easy for non-plasterers to pick up.

I think we need a pic of the other end (the end nearest the camera position, where the stairs open up and there is no wall on the L). Likely no problem spanning from wall to wall in the 'distance' of this photo (where the coats are), but then nearer the camera you only have one wall... Is there a 'stub' of wall behind the camera on the LHS so you can bridge across the stair opening?

I used to hate doing footings and blockwork in trenches, because I did not do it that often. However these were generally small - medium extensions where the footing job was too small to be of interest to a busy brickie. So I was really picky of my own work... So my out-of-plumbs' or 'out-of-squares' were tiny, as I was always pulling myself up - and checking again... and again... To lift a term (thanks @BotusBuild) you need someone who gives a sh1t - sounds like @BotusBuild knows the person. Good luck in the 2nd go.

Hmm. What does that out-of-plumb bubble represent? How far is it leaning in how tall? From LABC Warranty: "How far out of plumb can a wall be in the UK? Wall panels should be erected to the following tolerances: • +/-10mm from plumb per storey height. +/-10mm from plumb over the full height of the building. +/-3mm from line of sole plate, with maximum +/-5mm deviation from drawing". In pic 3 (with a slack line on top of the blocks) where was the line when the blocks were laid? Is this the brickie you were planning to use above ground?

Glad you've found a window of opportunity.

When you say 'partially' do you mean 'the roof, not the walls' or 'only some of the roof'? The former I'd say is OK, but if 'un-airtight' means 'breezy as owt' it probably won't gain you a great deal. If you do propose to insulate the roof can you get to the gables to drill ventilation holes in the gable at each end (you'll need a good few between each pair of timbers)? For minimal structural diminution you ought to drill on the centre line (75mm if they are 150 timbers, for example) but that limits the insulation you can get in. It could still allow 50mm though which (crudely) could drop the U value from say 2.0 to say 0.5W/m2K, roughly adjusted for the 'thermal intrusion' of the timbers. If you are pumping in heat it will reduce the heat loss. If you are expecting it to keep you discernibly warmer on a cold day with the only heat input being the c100W of you I doubt you'd feel a huge difference.

No-one (except me!) has yet picked me up on the fact that using PIR on the top would in effect act as a 2nd VCL where you do not want a VCL. If you substitute 30mm rigid (breathable)wood-fibre you'd get 0.1609W/m2K. I don't think BCO would quibble. I have no idea of the size of the job but it may be that if you took it outside the roofing job it may drop in price. How many m2 are we talking about? Possibly the trickiest bit of all will be removing the floorboards without excessive damage, but it can be done by punching the nails through the boards before you lift them. I did that on a 32m2 floor. We allowed for 20% replacement boards and got away with <5%.

Clarifications: 1. I should have said 'replace the floorboards' after adding the layer of PIR. 2. The VCL goes in 'hammock-wise' first, and the insulation goes over that - the mineral wool within the hammocks and the PIR on top.

And another thought: Are the 'rooms' in the 'attic' habitable rooms, or are they used as such? One assumes not as there is only ladder access. If, then, although there is a floor, they are storage spaces only, then the thermal line above the habitable spaces is arguably the floor - like any conventional 'loft'. Lift the floorboards, put 220 between joists (with lambda value 0.044W/mK that would give you an R value of 5m2K/W) and sit a layer of 25mm PIR (Kingspan/Celotex-type board) above. That will give you a U value of 0.1629 without the 'base case R value' (which is 1/an assumed U value of 2, so 0.5). Add the 'base case R and you get 0.15. While laying all this 'engineer' the ventilation so it all comes in the eaves and over the insulation and the job is a good one. For extra peace of mind lay a vapour control layer (Pro Clima Intello Plus is pricey but good) between and up and over all the joists in 'hammocks', and tape all joints and perimeters to keep water vapour out of the void space (and get a really well-sealing hatch too).

The only time I saw a contractor try to invoke the '15 year rule' it was for an external wall insulation job where they had installed 40mm phenolic board, not 50 as per their quote which would have met the wall target of 0.35 at the time (pre-2010). BC insisted that the '15-year assertion' was backed up by a SAP calc. The SAP assessor totally misunderstood the builder's 'brief' (if there was one) and (with a torturing of mathematics which even I - a relative mathematical ignoramus - could not have managed), managed to 'prove' that 50mm of phenolic *would* pay back in 15 years (remember he was supposed to prove it *wouldn't*! So BC insisted he install 50mm (which in reality meant a layer of 20mm over the existing rendered 40mm. Not the world's most impressive moment.

Before you can 'dial it in' you need to know what flow temp the system was designed for. I always used to ask for a re-calc if I saw a quote assuming a flow temp of 55 degrees. That can be a way of getting out of changing many (or even any) rads, but I'd rather consider changing them and get an answer as to what the CoP would be at a lower flow temp.

Bldg Regs require 0.18W/m2K for an extension. Yes, yes, yes!! Do wet plaster. If you must adhere plasterboard do it either on full-coverage adhesive (rare as rocking-horse poo) or with full perimeter bead and close cross-hatchings. Better still, don't use it!

I agree there are epc assessors out there with a huge amount of general and 'eco' nous. I also know there is at least one who cannot recognise EWI. Yes, his certifying body was as nonplussed as me. I wouldn't have asked him to give any opinion on air-tightness and I am not sure that the (basic) training equips them. Some of the air-tightness testers I know only do it with a 'blower-door and thermography package', but I would guess a 'pressurise (or de-pressurise) and go' person might do it for £400 or less. Any members with recent experience?

Fingers are crossed on your behalf.

Thanks for this. No PP a/c at present. Will look at getting one. It accepted my details 'in English', but then when I moved to (card) payment it reverted to German.