Loft insulation

Phlik

Evening all

I'm about to increase the lagging in the loft (currently about 50-60 mm thick, standard itchy stuff ). According to various sources it should be 200-300mm thick. Not a problem, easy enough to do, but, like most people I use the loft for storing various bits of tat. To lay the insulation properly I'll have to run some deeper beams across the existing beams so I can board part of the loft space to put the junk back in, so easy job got alot more involved and more expensive.

If I was to use Xtratherm (foil coated foam in various thicknesses) instead would this be as good (or better if I'm lucky)? I'd be looking at somewhere between 50 and 100m thick.

Cost wise to cover 42m square

200mm loft insulation £180 + cost of new beams

50mm Xtratherm £200

So, experts, what say you?

Phlik

OddjobKIA

is it nessecary to actually put more insulation up there????

Phlik

Apparently so

http://www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Loft-insulation

We've got at best 50mm thick insulation, so decided to sort it out now at the beginning of winter. Will be looking to sell the house next year and this kind of thing goes in your epc , hip etc :rolleyes:

Phlik

lagi

Interested to see answer, as i have building regs. spec sheet and it says to lay 150mm between joist and then 150mm over the joists going the other direction. Likewise i would have liked to have used that for storage. Or do you just crush it with boards?

Kiran

You can't compress the loft insulation and have it work at the same level of efficiency. If the insulation is compressed it makes it harder to trap the heat in. Current building regs say you need to have 270mm if layed in the criss cross pattern, but if you lay it all in one direction it increases to something in the region of 600mm. This is due to the transfer of heat through the ceiling joists.

Depending on the age of the house adding a sub frame in the loft to raise the boards up is an ideal solution, but it is worth noting that what you've got in your loft is generally only there to hold the plaster board up from the ceiling below and is not the same as the joists you have holding your first floor up. If it is possible to do so, then attaching your subframe to the gable end walls by using joist hangers will stop you from adding any additional load to the ceiling joists.

The other solution, which is more exspensive is to insualte the rafters, this means you have no problems with laying loft boards and also means that you wont be subjecting your stored items to great changes in heat throughout the seasons

Hope this helped.

Barneysmom

WEe've got half of our loft boarded, figured the heat can't get through the stored stuff that's up there. The rest, round the edges, has a big huge amount of insulation, it's over a foot high :rotfl:

Phlik

Kiran wrote: »

Depending on the age of the house adding a sub frame in the loft to raise the boards up is an ideal solution, but it is worth noting that what you've got in your loft is generally only there to hold the plaster board up from the ceiling below and is not the same as the joists you have holding your first floor up. If it is possible to do so, then attaching your subframe to the gable end walls by using joist hangers will stop you from adding any additional load to the ceiling joists.

Thats the way I was thinking of going if I go the rockwool route. Trouble is the job gets very labourious and expensive. Theres also no way I'd get the beams up there without cutting into at least 3 pieces.

The other solution, which is more exspensive is to insualte the rafters, this means you have no problems with laying loft boards and also means that you wont be subjecting your stored items to great changes in heat throughout the seasons

Could I not do this between the ceiling joists?

Ideally I'd like to use ceroflex between the joists, then board back over the top. Would I have a problem when I come to sell the house (hip, energy certificate etc). Also would it be as good or better than standard rockwool?

Cheers

Phlik

tomfun

The easiest and less itchy way would be to insulate your rafters,screwfix do a 25m x 1 m of airtec foil it is brilliant stuff ,just staple it to the rafters and make sure you tape the joints with foil tape or silver ductape
http://www.screwfix.com/prods/21112/Building/Roofing-Insulation/Airtec-Double-Insulation-1-05m-x-25m

If you fit it propely and tape it all it keeps all draughts out and keep more heat in.

pugmanic

I was thinking about this the other day. Athletes use Foil space blankets which reflect approx 80% radiant heat. You can purchase these for approx £1 (actually less but makes maths easier). Each sheet works out at approx 2.5 M2.

25M2 for £83 in Screwfix or 25M2 for approx £10? Hmmm?

If you lay the foil under the FG insulation then the 20% heat that isn't relected should be absorbed by the FG insulation...

Just a thought.

27col

If what is in the roof is, as you say, junk, then why are you hoarding it. It seems to me that anything that has been in a loft for, say two years, is not wanted and should be got rid of.
I am sure that if, foil space blankets, were as good as has been stated, why would anyone put any other sort of insulation in a roof. It smacks of wishful thinking to me.
I have just cleared out my roof and installed more insulation to raise the thickness to 250mm. The roof was full of cardboard boxes of every tv, computer, hi-fi, and other appliance that we have bought over the last 30yrs. It is now all in the reclamation tip. There were also about 250 model fire engines and buses and their boxes. Now they have all been reunited with their packaging and stored in boxes of the same size. They fit into a vastly smaller area and are no longer stored in the roof. I was going to compromise by just boarding a small area near the hatch, but decided against it and insulated the whole roof. Several boxes of other stuff have gone to a local cat charity. Result, snug as a bug in a rug!