Loft insulation

barker77

Looking around it appears that loft insulation has got expensive again.

Can anyone recommend anywhere that is selling it at a decent price?

Thanks

Joyful

British gas are offering it Free to Non customers.

Smiley_Dan

Look on your local Gumtree and Facebook sites. Brought eight rolls of 200mm for £15 last weekend!

Also check out Insulation Place.

Also Seconds & Co.

Remember to max it out, aim for 450-500mm. 270mm is not enough.

Even more important, install it properly.

Skools_Out

barker77 wrote: »

Looking around it appears that loft insulation has got expensive again.

Can anyone recommend anywhere that is selling it at a decent price?

Thanks

Have you tried Ebay? Or Amazon?

You can usually find anything on those sites, and generally pick up a bargain from one or t'other

barker77

Smiley dan - that seems like a lot of insulation! Is there a good guide on installing it anywhere and any reccomendations as to what type to get i.e glasswoll over something like earthwool (meant to be less itchy?)

Smiley_Dan

Earthwool is a trade name like rockwool. They are both mineral wools and nicer to work with than glass fibre. All insulation products have a BBA certificate which shows the thermal conductivity, that is the way of comparing their insulatory abilities.

There's no all in one best practice guide I have seen. A few thoughts.

Before doing anything seal all holes through the ceiling. Seal cables with polymer sealant. Cables for light switches, light fittings, smoke alarms etc. Seal down lights by changing to LED and place a large flower pot over, seal in cables. Seal plasterboard ceiling to wall junctions with foam (get a foam gun). This is very difficult at the eaves. Seal all pipe penetrations etc. Seal any gaps opening into the ceiling from internal walls. Seal the loft hatch.

Airtightness is very important to the effectiveness of loft roll. Also seal joist ends with foam where they penetrate the wall.

Install a rafter tray to ensure you get adequate ventilation. Actually this depends on the roof but normally you need 5-10mm continuous air gap between the insulation and sarking (felt). I use EPS (polystyrene) for the tray. Try to lay some loft roll under the rafter tray so it falls against the top of the outside wall. Ideally join it to any wall insulation but again this is difficult without a lot of faff.

Lay loft roll between joists at the depth of the joist. Then other layers above at right angles. Absolutely no gaps anywhere.

It's important to get even coverage because thinner bits of insulation have a disproportionate effect on average overall U value.

All cables should be above the insulation - you can get away with short lengths at low load.

Insulate the loft hatch with EPS and work out what will happen when you close the hatch.

barker77

Is it ok to insulate over existing boarding, I can remove it but keen to avoid the hassle if possible! Not interested in using the loft for storage....

Smiley_Dan

It's far from ideal. A few reasons:

Your thermal envelope is larger so more space to heat.

Lots of possibilities for air leakage under the boards, the masonry itself, gaps around joists, holes where services exit.

Finally you won't be able to address the eaves properly so you'll have a band of uninsulated ceiling running along the eaves.

All in all the performance will be significantly compromised. Better than nothing at all but not as good as it could be.