Loft insulation advice

[whiskywill]

What about these? http://www.toolstation.com/shop/Access% ... 303/p44016

 

[KevM]

I used some of those Toolstation loft legs - they worked fine with chipboard flooring.
Would I want to clog dance on the finished result? No.
Do they act as a safe base for the odds and sods that I'm waiting 10 years before throwing out? Yes.

 

[mind_the_goat]

You could raise the height of the joists by pinning some 4x2 (or whatever size you need) on top, then put your existing flooring on that.

 

[scholar]

DW

I have had similar issues and have looked at many solutions - I rejected all of the foil products, not because they don't work (in fact I think it would not harm as an additional element in the way you have suggested installing it), but because they can interfere with aerial reception and I have loft aerials.

What I used is this stuff (it's not that cheap, but I was lucky to find a big quantity being sold as surplus on eBay - it was a fairly hilarious sight carrying it all home on top of the Land Rover roofrack, easily doubling the height...)

http://www.space-insulation.com/product ... board-eco/

I think these are branded slightly differently to the boards I have been using, which I recall was branded Polyfoam - same stuff. The blurb on the link suggests various methods of installation, but what I have done is 100mm fibreglass between the joists, then 50mm Polyfoam on top of the joists and then 18mm t&g chipboard on top - the Polyfoam just sits in place and the chipboard is screwed to the joists through the Polyfoam (ends of the Polyfoam are cut to sit on a joist, but this is not necessary with the chipboard).
It all feels very strong and overall is a good arrangement - it is more work than most people would want to put into insulating their loft.... But it was the best technical and practical solution I could find.

NB the point about the wiring is important - I have rerouted stray cables into a logical grid either running down the sides or in surface trunking, except in a few areas where this would be annoying - here I have cut a channel for a suitable sized trunking to be let into the top side of the Polyfoam - this is only for low current circuits eg a single light fitting.

I have not compared the compressive strength qualities of Kingspan etc to the Polyfoam, but if it is at least as strong, it would be a good alternative I think (although bear in mind that Kingpan comes in 8x4 sheets, whereas the polyfoam is 8x2.

Polyfoam also makes a good sacrificial cutting surface for cutting sheet materials....


Cheers

 

[beech1948]

DW,

Is there any way you can produce a wood based floor riser say 8 inches high, floor with chip board etc. Some of ones suggested are simply plastic so moulded and wood is stronger and easily shaped and fastened.

I think polystyrene is a fire risk and should not be used. Burns/ignites quickly and when molten drips fire down on everything. Ask the fire brigade advisory staff.?

regards
Alan

 

[RossJarvis]

I've spent a fair bit of the past few weeks walking about on unprotected celotex, placed on a concrete floor. Then someone bunged 5 ton of screed on it. If it's fully supported and doesn't have a high "point load". It seems to take a fair bit of abuse. Of course, ply over the top would make it much more robust. I can't stand the fibre-glass wool stuff, particularly laying it. It also acts as a perfect sponge to soak water up and rot stuff which the foam board doesn't.

 

[devonwoody]

Thanks to those latest responses, should be a solution there.
Have to have a word with an electrician and find a way to reroute wiring, mainly lighting, but there is a 6mm cable to a shower and also to the workshop up there.

Also when we have to replace the boiler it is going to have to go up in the loft on an outside wall and that will need a pathway up there.

 

[AndyT]

I went through a similar exercise and ended up with a hybrid solution. In the full height area where we need storage I left existing fibre between the joists and put closed cell boards across, with chipboard loft panels on top, screwed down with long screws. In the inaccessible parts I just topped up the fibre. But it was a fiddly, horrible job to do. I know that you won't get anything like it on the subsidised free insulation schemes, though they can at least mean that the materials are cheap to buy. And I did reroute all the cables to run above the insulation.

 

[morfa]

I got some 2" by 8" joists and put them at opposite angles to the existing joists. Used metal plates to join them to the existing joists. They're about 400/500mm apart, plonked standard loft insulation over the top and then I've got normal loft flooring over the top of that. Cost me about £300 for the various materials all in.

You've all got me worried about the cables however. I've just got standard mineral wool loft insulation and it's not compressed, just laid loosly over the existing insulation (and cables). It's been in a year and the house hasn't burned down (yet). Is it worth getting the sparky in to lengthen the cables to they run over the flooring?

 

[AndyT]

An answer on cables from a non-electrican. When I looked into it to do mine, I found the reason for keeping cables clear is this. Cables are sized so that when carrying working current, they can safely lose the heat produced in the conductors. If you prevent a cable from cooling, by covering it in insulation, the Max rated current reduces. Similar downrating applies if buried in plaster. I looked at the total load on the loft cables and since they all now connect to low energy lights not 150W bulbs, the total is tiny. So it would be fine to cover them. But I played safe in case a future owner wanted to do something different.