Way way way off topic. Loft insulation
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Gonna be replacing mine shortly. The recommended thickness is 8" but my joists are 4" and I want to board out the loft.
The obvious thing to do is fit more 4" joists across the originals to make 8" and have 2 layers of insulation crossing eachother then board it out but that seems a lot of faffing.

What have you done? Is there a better way?

Paul

I seriously doubt it!

thats the best way to do it Paul it will remove any termal(SP) bridging which adds about 20% to your BER

i suppose you could use kingspan or a similarly more dense material that the rolls of fibre stuff,


carl

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you can now get an insulated chipboard laminate for the loft but I've no idea how good it is or how expensive

kingspan or alike

Just come across this stuff. Looks good, though probably costs a bomb.
http://www.knaufinsulation.co.uk/press_rel...uf_insulat.aspx

I seriously doubt it!

I did mine the way you initially suggested, a whole series of additional 4"x1" at 90 degrees to the existing joists.

The main hassle was the existing joists (bottom part of factory made trusses) are all crosslinked with diagonal runs of 4"x1" (long face down) sitting on top of the existing "joists" so all my new "joists" had to have quite long 1" notches cut in the bottom of them to clear this bracing, all had to be measured in the loft then cut in my workshop..... took ages.

That's why I used 4"x1" for the second layer of "joists", lighter and easier to cut all the notches. Bit more wobby than 4"x2" would have been but fine once the first few boards were screwed down.

Schrödinger's cat - so which one am I ???

the Knauf stuff is what i was thinking about - your correct - it wont be cheap but its good stuff.

have a look around on the net - there are a few places that supply seconds at a greatly reduced prices

if the insulation is 8" thick then rip in half, you will need to have air circulation between the board and insulation, so insulation in between the joists, then lath and board ontop of the lath

Cant you get thin insulation, that is the equivalent of much thicker stuff ?

Or if not rolling it out, you could fit the flooring, and have the fibreglass pumped or blown in to fill any voids

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Depends on he span, but adding another layer of 4" joists is not as strong as adding 8" joists along side the 4" if you are boarding out.

Thats what I did, making sure the 8 inchers rested on the walls below.

(Avoided moans fron the other half about the cracks in the ceiling)

doubling up the joists is a bit expensive if you are only using the space for storage (unless of course the existing joinsts are already extremely undersized)