Advice on insulating boarded loft

I have an old Victorian terrace with 100mm insulation in the loft.

I was just going to get a few rolls of some spaceblanket insulation form Wickes,but half of the area is boarded.

Whats the best way to deal with those areas?

I have seen Knauf Spaceboard, and that may be a solution, but how strong is it?

If not what work is entailed if I raise the joists,to fit in extra insulation?

Do you need all the boarded area?
The house we moved into has a boarded loft with joist depth insulation underneath. I allocated an area for storage & have just covered the rest of the boards with insulation.
That way if I need the storage in the future, I can move the insulation out of the way & make use of the storage.
We have a low pitch roof, so making the joist void deeper (raising the boards) & insulating underneath would have rendered the space too low to move about in.

I think you can buy spacers from places like B&Q to give you more room between joist & boards…

I raised the floor of our loft my laying new joists at right angles to the existing, then boarded over that. By doing this you can lay two lots of joist-depth insulation.

The quick and dirty method is as per stumpy – it’s easier if you use the insulation in foil blankets, so you don’t get covered in fibres if you need to move it.

My favourite insulation material at the moment is R3 120mm recycled polyester. Nice to work with and doesn’t create and condensation worries.

get some celotex boards, lift your boards, lay the celotex, then relay the boards on top and screw all the way through into the joists.

I bought a load from here, http://www.secondsandco.co.uk/ for a reasonable price.

100mm of celotex/kingspan is equivalent to 300mm of quilt (fibreglass etc.)

Dave

I’m not sure Celotex is strong enough to be supported just by the Joists and then take boards / people / stuff. I’ve got rock wool insulation in the joists, then 18mm chipboard then Celotex (can’t remember what – probably 100mm) then another 18mm board. Possibly a bit of an over kill but I had the ceilings down so I could lift big boards into the loft at the time!

So if you’ve already got it boarded you could just cut some celotex sheets into a size you can get into the loft, slap it onto the existing boards then board over the top with the small T&G loft boards that DIY places sell.

All good info guys. Celotex just happens to have been bought by the same parent company as mine so my company discount applies too! 🙂

What sort of insulation does having a loft full of junk afford? Boxes of cds and bags of clothes must be quite good.

these are useful if you want to have more insulation;

http://loftstoragestilts.com/%5B/url%5D

lose a bit of headroom though.

Celotex is fine to rest on joists and be overboarded.

If you look at their website, that is one of the recommended install methods. If you have the option, it is best to use T&G boards, so that they will spread the load properly; otherwise you may have to faff with lining the board joins up with the joists.

Boarded section of my loft has 100mm of quilt, ~95mm of foil faced kingspan (seconds) and 18mm T&G chipboard. The eaves have 300mm of quilt.

Dave

I fitted a raised floor in our loft by fixing my own joists to the rafters.

I’m a little concerned that my roof may collapse, but this was a few years ago and it seems ok so far… 😕

Isn’t four inches of insulation enough?

Marked for later 🙂

Isn’t four inches of insulation enough?

Four inches is never enough 8)

Recommended insulation depth now is 270mm

Dave

Info

Seems like if you’ve got 100mm of insulation you’re 80+% of the way there to what the recommended 270mm achieves.