loft insulation

[gucciman]

i want to board out my loft to use as storeage space but first i need to improve the inuslation.

ours is an old house and the joists are 300mm apart rather than 600mm. ive been down to b and q and the loft insulation they sell is all 600mm

is it possible to buy 300mm wide insulation?

does anyone know what depth the insulation needs to be?

thanks

[Ethel]

Wickes is usually better for this sort of thing than B&Q.

300mm thickness is the recommended depth for good insulation, but 200 mm is better than nothing.

You can certainly buy 300mm widths of insulation - that is the minimum width available.

I assume you are in the UK. Check to see if you are entitled to free loft insulation from the energy action group: http://www.eaga.co.uk/

[curiosity]

We've put Kingspan in our loft it's a bit dearer but really good.

[antiguru]

or use a natural product like sheepswool which can be packed in to any space. Google sheepswool insulation for local suppliers.

[eggobako]

if you live in certain areas they wiil give you a grant to fund your loft top up but you have to gat them to do it their way i.e.let them come and tell you it needs topping uop ( even though you know this!!) you can buy rockwool insulation in 300mm widthes at any builders merchants but be careful YOU SHOULD NEVER COVER ELECTRIC EQUIPMENT WITH THE INSULATION!

[gucciman]

the reason i dont want to cut it in half is because its nasty stuff, tricky and unpleasant to work with and the less messing about i have to do with it the better.

what do you mean by you must never cover electrical installations with the insulation? the existing insulation covers up the light rose in the bedroom ceiling, is this dangerous then?

and does anyone know much about the insulation in the silver foil that i saw in b and q?

[buildersmate]

There are various products at various prices and at least 3 are mentioned above. Glass wool or rock wool is one family and the one that you say you don't fancy cutting. Its OK if you cover exposed skin and wear and a simple dust mask, but your choice. I think you are very likely to pay a premium if you can find it 300mm wide because the standard is 600mm. If you cut it with a saw whilst still rolled up tight it wouldn't be a problem to do. Some 600 rolls do come with a 'split' down the middle so it is really easy to pull the two halfds apart anyway. The next family is isocyanurates - mainly known as Kingspan or Celotex. These are rigid foams, come in big sheets that are easily cut to size with a saw, making lots of foam 'crumbs' as you do it - no dust. Their insulation properties are far better than wool for the same thickness. The stuff you have seen in B+Q sounds like thermal bubble wrap. Never used it - believe it to be expensive for the thermal performance. See here for a generic comparison chart.

http://www.sheffins.co.uk/app_guide.htm

[buildersmate]

Forgot to answer the electrical cover-up bit. Covering ceiling roses is not an issue. The things you mustn't cover are inset lights in the ceiling because they rely on heat from the bulb going upwards through the ceiling and they get very very hot if you do this. Just leave a breather hole the same size as the light. There is likely to an issue if you are trying to board over such areas of your loft with such lights in the ceiling below because the depth of roof trusses are usually 100mm. So you should leave a hole in the boarding as well. Lastly, there's no point in putting thicker insulation than you have depth of roof truss because you are going to squash it gound anyway - so for best impact use Kingspan or similar product.