150mm or 200mm Insulation?

eamon11

Hello,

I am putting in earthwool between the ceiling joists. The joists are 175mm. On top is floored. Is 200 mm insulation compressed to 175mm or 150mm insulation more practical?

Thanks a lot

elastico

I think if you compress that stuff it defeats the purpose. Google it to check.

TheLastMohican

Why not use the recommended thickness?

eamon11

anyone know the answer to my question?

bonzodog2

Add 25mm of battens to your joists and use the 200mm insulation

MicktheMan

eamon11 wrote: »

anyone know the answer to my question?

You already got it here:

elastico wrote: »

if you compress that stuff it defeats the purpose.

eamon11

thanks guys,

joists are in place and boarded over so there will be no adding battons. I assume from your reply Mick you are saying use the 150mm insulation leaving a 25mm air gap?

Calahonda52

eamon11 wrote: »

thanks guys,

joists are in place and boarded over so there will be no adding battons. I assume from your reply Mick you are saying use the 150mm insulation leaving a 25mm air gap?

Theoretically yes, in practice unlightly

So the wool is going to be shoved up from underneath and it will be held up via friction until the ceiling is slabbed?
It will be up and down, as as the floor is above, more up.

What steps have u taken to make sure no air can pass lengthways, horizontally across from one end to the other in the space between the joists.
If there is air flow through this space then the insulation is reduced in effectiveness because its the retained air in the insulation that makes it work, not the material.

MicktheMan

eamon11 wrote: »

thanks guys,

joists are in place and boarded over so there will be no adding battons. I assume from your reply Mick you are saying use the 150mm insulation leaving a 25mm air gap?

Yes. The trapped air in the earthwool is the insulant. Compressing it results in less trapped air and therefore less insulating effect.

TheLastMohican

MicktheMan wrote: »

Yes. The trapped air in the earthwool is the insulant. Compressing it results in less trapped air and therefore less insulating effect.

As anyone that reads the directions knows!