100mm joists, how much insulation in between. 100mm or 150mm

[Stonedofmoo]

Hi guys

If I have 100mm joists should I put 100mm insulation between them, or is it better to pack in 150/170mm? I only ask because seeing how tightly packed those rolls of insulation are I was a little skeptical it would expand to fill the gaps fully

Cheers

 

[noseall]

Is this loft insulation?

Current reg's ask for about 280mm (glass-wool). We normally install 150mm between and another 150mm across, all laid fairly loose, i.e. not packed or rammed.

 

[Stonedofmoo]

Hi there


Sorry I didn't explain myself that well. I'll be laying SF19 Foil over the top of the joists as one big joined carpet, and then boarding on top of that so I only need to worry about the area underneath the SF19 and between the joists which is 100mm high.

So do you recommend putting in '100mm' glass wool, or pushing it down a bit and compressing in 150mm wool?

 

[noseall]

Use 100mm glass wool.

 

[Stonedofmoo]

Lovely, thanks for the advice