I think you misunderstood. Best put Rockwool up to joist height then lay Kingspan over the joists, this prevents thermal bridging via the joists. Then loft boards over the Kingspan. Only the part of the loft where you can walk is worth boarding, unless all the loft is used for storage.
IMM's uni only taught him about straight lines and binary thinking.
Its no good talking to him about curves and maxima/minima.
The only curves he ever takes notice of, are on page 3.
And when he switched to the socialist worker, he lost track of even those.
So you studied to build bridges and design electronic boards all in one course. My, oh my. Was this skule in Toytown.
Wouldn't the boards get quite squashed where they lay on the joists? Obviously, crosslaying is the best solution. However, if the OP is only going to fit stuff between the joists, it may as well be Kingspan than rockwool.
Christian.
Many ways in which to get around that. I think Kingspan do a board which mean for floating floors so this can be used, or you can always counter baton with baton the thickness of the Kingspan and put boards over that.
That is true, but There will be lost of waste with Kingspan, unless you path it all in and the remainder scatter around the loft in places that nothing is stored or walked on.
Laying over the joists and taping up the joins will add it air-tightness too.
The problem is that with a 100mm joist height you aren't meant to store anything, other than insulation in your lost. Its one of those cases where the builders use the absolute minimum they can get away in order to save a few quid and you end up with some valuable storage space that you effectively can't use!
cheers
David
Nah. I've seen loads of houses with 100mm loft joists. They're all used for storage!
Floor joist sizes are so large to avoid flexing the ceiling as people move about, not to stop the things collapsing. Light or even medium storage is usually OK, as there is little movement. Any bad results are usually a few hairline cracks, not stuff piling into the room below. Obvious, large water tanks or big boxes of books need special consideration.
Christian.
Yes, and that is where cross laying more joists , maybe herringbone bracing and a few hangers up to teh ridge/radfters makes sense. Total insulation depth comes up to maybe 8 inches with only where the joists cross as 'cold bridges' and boardiong out the loft stops draughts getong in any less than perefectly insulated places.
I have just complete boarding out my loft with 150mm insulation (rockwool) and its made a lot of difference. Its icy up there when the wind blows (silly building regs vents are enough to take every ounce of moist air out in about 1.2 seconds). Once you get to this sort of insulation depth, the real danger is tiny cracks that allow air movement alongside celotex and through the rockwool.
If yu have as I have, hollow rockwool filled walls, you then discover that things like e.g. power sockets, or the odd crack round a window frame, lets in a tiny icy draught...from air moving THROUGH the insulation and getting into the rooms.
Going to IMMlike levels of insulation only works if you can stop up each and every one of these micro draughts: This takes patience, and decorators caulk and frame sealer inside, and attention to detail up in the loft as well.
I sometimes wonde if much more limited ventialtion, and an electrical dehumidifier in the loft might not be a more energy efficient way to keep a cold roof dry, and allow the loft airspace itself to become an insulator...
This is very true. Timber will suffer unacceptable deformation long before it breaks. Especually on longish spans (a couple of meters or more)
Yes. It was in Cambridge.
But arm waving with realism. All I read is that energy will become more scarce and more expensive. As it becomes more exp[expensive so will insulation too. best pack it in now while it is cheap enough. You will not regret it in the future.
See above.
Who said focus on this alone?I never. I said pack in as much as you can while it is cheap as it will not be, neither will energy, in the future. probably sooner than later too.
See above.
That is still cheap and easy to do, even for a DIYer.
It does, as you can tackle the loft easily and cheaply. You plug as many holes as you can, even the small ones.
"at the then current fuel prices"
That is clear above.
Not mine. Experts on the topic conclude this.
I have always said caulk every hole into the loft: around pipes, cables, etc. Also fit a vapour barrier on the loft floor, stapling down, then put insulation over.
I have always though that may be beneficial. Seal up all vents and install one. The BCO would not like at, as if the de-humidifier fails you have problems. An accurate humidistat would need to be fitted to reduce running costs. There again install a vapour barrier on the loft floor to prevent vapour getting in.
A bulldozer should be run through the lot of it.
This is all qualitative stuff.
At some point it may well be interesting to do this, but at a saving of a tenner a year, when several hundred quids worth of heat is going out through the walls means that the focus should be on that now and situations where there is no roof insulation at all.
Quantitative arguments not qualitative.
That is not a reason. It's the difference between turning a light on or not - in cost terms a very small light.
On the immediate energy cost or with everything taken into account including replacement sandals for the author?
You haven't made a convincing case at all.
.andy
To email, substitute .nospam with .gl
Philistine......
.andy
To email, substitute .nospam with .gl
You missed it again. It is not a mater of either or. It is cheap to pack the loft full of insulation and super easy to do so. So do it. The walls leaking heat is another matter, and of course should be tackled eventually. To do the walls is not easy and expensive. because the walls leak heat more than the loft does not mean you ignore the loft, or insulate it to the level of then walls. You have strange logic.
Very convincing. Based on pure logic.
And through there as well?
In article , Dean Richard Benson writes
Whilst we are on the subject on loft insulation what's the consensus for insulating in, around and over the cold water tank? I popped into the loft the other day to set the traps for our annual tiny footed visitors and thought I must do something with the tank, at the moment I have the tank insulated and up on a platform with the patch of loft insulation removed underneath it, I was thinking of boxing the whole thing in with ply and some polystyrene sheet fixed to that to form an insulated box.
TIA
The usual method is to have a tank jacket and the loft insulation curved up and to the sides of the tank.
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