Which attic insulation ?

Satts

Which attic insulation is better to keep in heat, a fibreglass or an eco-wool ?

Also, should the insultion end at the wall plate or should it spill over the wall in to the soffit ( but not covering the vents completely ) ?

Is it better to cover top of joists as well as in between them ?

toshy321

Satts wrote: »

Which attic insulation is better to keep in heat, a fibreglass or an eco-wool ?

Also, should the insultion end at the wall plate or should it spill over the wall in to the soffit ( but not covering the vents completely ) ?

Is it better to cover top of joists as well as in between them ?

As far as I know you don't let the insulation into soffit keep a 50mm gap love 2 know an answer to your first question myself which keeps in heat more fibreglass or ecowool

Jimbo

You can compare the insulating properties of any product by looking at their certified thermal conductivities. The lower the conductivity, the better insulator it is.
The thermal conductivity of ecowool is 0.0425 W/m2K http://www.eco-wool.co.uk/downloads/Eco-Wool.pdf
The thermal conductivity of moy plus roll is 0.044 W/m2K http://www.moyisover.ie/upload/medias/uk/moy%20plus%2009.pdf

The ecowool is only marginally better.
You should insulate between the joists as well as over. Aim for at least 300mm total depth of insulation and dont compress it when you are installing. Maintain a contiunous 50mm ventilation space from the eaves to the roof ridge.

toshy321

Jimbo wrote: »

You can compare the insulating properties of any product by looking at their certified thermal conductivities. The lower the conductivity, the better insulator it is.
The thermal conductivity of ecowool is 0.0425 W/m2K http://www.eco-wool.co.uk/downloads/Eco-Wool.pdf
The thermal conductivity of moy plus roll is 0.044 W/m2K http://www.moyisover.ie/upload/medias/uk/moy%20plus%2009.pdf

The ecowool is only marginally better.
You should insulate between the joists as well as over. Aim for at least 300mm total depth of insulation and dont compress it when you are installing. Maintain a contiunous 50mm ventilation space from the eaves to the roof ridge.

I'm insulating a gable roof which has been left exposed with no joists so I just have to insulate rafters and put tand g timber on it what insulation would be best to use rafters are 9x2

Jimbo

As you have limited depth to play with, I would install rigid high denisty insulation such as Xtrathem Rafterloc or Kingspan K7 between the joists. You will have to maintain 50mm ventilation space behind the insualtion, so the maximum you can install is 180mm between the rafters.
To achieve good u values, you should also insulate the underside of the rafters with insulated plasterboard.

toshy321

Jimbo wrote: »

As you have limited depth to play with, I would install rigid high denisty insulation such as Xtrathem Rafterloc or Kingspan K7 between the joists. You will have to maintain 50mm ventilation space behind the insualtion, so the maximum you can install is 180mm between the rafters.
To achieve good u values, you should also insulate the underside of the rafters with insulated plasterboard.

Cheers for reply jimbo I was told that rockwool or earthwool would be sufficient enough with plywood screwed up to keep it in place by a another source not that clued in with insulation so you reckon I'd be better off going with the xratherm boards.

Jimbo

A single layer of rockwool/eathwool wouldn't come close to u-value required in the cuurent building regs. The insulated plasterboard will also deal with the thermal breaks from the rafters.
Don't skimp on insulation when you have the chance to improve it.