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Yeah, anyone tried removing EPS? Wondering – if tiles/felt rolled back enough to look straight down the cavity, could the EPS be smashed by prodding with a long bar, then vacuumed out? Laborious, but … I'm sure there will be much call to remove cavity wall insulation in future – the cavity space and the thermal massiveness of the outer skin will become too valuable to be isolated away from the interior.
Jablite is EPS and shd (I'd say) be assumed get waterlogged if used below GL. Perimate Styrofoam is grooved XPs, with a geotextile layer bonded on to keep the grooves clear and to protect against backfilling, when used as external downstand insulation.
I've wondered this. Presumably something rigidly incompressible like Foamglas as cavity full-fill, mortared in if necessary, would resist inward pressure, whether from trucks externally, or from raised backfill internally, as effectively as concrete cavity fill. In that case, why not high-strength XPS?
Before diving into this, still something I'm not clear on – is partial water vapour pressure proportional to relative humidity, or to absolute water vapour concentration? If the former, then partial water vapour pressure would increase by cooling the air (with no additional vapour added) – sounds counter-intuitive.
3 April 2009 at 11:08 am in reply to: Re: Re: thermal bridging around windows with wrap around external insulation #35556I'm none the wiser, will ask again on another occasion.
Ah, right, if 'decentralised' means several self-contained individual-room units, then obviously inefficient. I just wanted to be quite clear that by 'decentralised'. Mark didn't mean “several local-area fans with short individual ducts to each room, but still all brought back to a single heat exchanger “. Which are you talking about, Mark?
last I heard decentralised MVHR does not achieve the same heat recovery efficiency
Why would that be? Does 'decentralised' mean several local-area fans with short individual ducts to each room, but still all brought back to a single heat exchanger – or something else?
1 April 2009 at 1:30 pm in reply to: Re: Re: thermal bridging around windows with wrap around external insulation #35554If a manuf cd use glass of Ug better than 0.7 (which wd be gd against downdraughts) he's allowed no credit for that, so has no alternative but to improve the frame instead, and may as well use cheaper, downdraughty glass no better than 0.7.
31 March 2009 at 2:13 pm in reply to: Re: Re: thermal bridging around windows with wrap around external insulation #35552Going back over this with great interest, but slightly thrown by what may be a misprint:
by limiting the Ug to 0.7 it helps to ensure that the manufacturer does not place undue emphasis on the design of the frame
If you confirm Mark that that should read 'design of the glass', then I'm happy, otherwise baffled!
The attached is what we're talking about?
I also had a question in my previous post on this thread, previous page.
I've had that report awhile, in fact was given it by the boffin in person at some Show, and continue to do my best to fully grasp it, not helped by the units on p4/5, which I'm sure are wonky, or at least non-standard.
Niall, the good bit you've written is v interesting – thanks. But the case isn't made there, for intelligent membranes. Could you (or someone) explain better than the above report, just what intelligent membranes set out to do, why they do it better than non-intelligent?
And is it really relevant to maritime UK, compared with continental inland European climate, where extremes of both temp and humidity are greater; their winters are colder but bone-dry, summers hotter but more humid?
Open a window and bring in a £26 electric convector – it's a brief emergency!
psi I sort of understand, but what's psh?
How did you manage to edit my post, Nick? – i'm a moderator and thought it would be clearer than adding a reply further along the thread.
Oo I don't like that – of course I can go in and edit your edit!
Sounds like you're not concerned with that 5:1 inboard to outboard ratio of vapour resistance, if putting low-resistance Panel* both inboard and out, or even just inboard. I'm favouring OSB because it does have slightly higher resistance, tho still low. My data http://www.greensteps.co.uk/tmp/assets/1163178050906.pdf says 20thk wood fibre 0.5MNs/g, 9thk OSB 1.95 – just right. Do you think that that 5:1 is unimportant? I know it as the 'breatheable construction' rule-of-thumb, but where can I find the authoritative basis for that?
Would the keepers of AECB wisdom say that the 'breatheable construction' idea, in this form, is unproven/unsafe/just a marketing puff?
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