Super quilt insulation

[MarkSSL]

Has anyone used this in a stone wall property? I’m thinking of using it in our roof, under the rafters, then batten with plasterboard. This will leave plenty of ventilation between the felt and insulation plus a 1” gap between insulation and plasterboard.
Sound about right?
Thanks

 

[MarkSSL]

Has anyone used this in a stone wall property? I’m thinking of using it in our roof, under the rafters, then batten with plasterboard. This will leave plenty of ventilation between the felt and insulation plus a 1” gap between insulation and plasterboard.
Sound about right?
Thanks

Just seen they do breather quilt. May go for this to avoid condensation.

 

[endecotp]

It's a multi-foil insulation, right?
It's a controversial technology. Why are you considering usijg it, rather than something more conventional?

 

[freddiemercurystwin]

It's a multi-foil insulation, right?
It's a controversial technology. Why are you considering usijg it, rather than something more conventional?

It's not so controversial now it's been exposed for the overpriced pointless product that it is! In order to utilise it you need an air gap above and below and you need an additional layer of celotex beneath that to get the overall makeup to comply with anything, thus making any space saving advantages redundant!

 

[MarkSSL]

I was only considering it as I only have 3” rafters and using more conventional insulation (Isover) I will need to increase the depth of each rafter by 3” to enable 125mm to be fitted with a 1” airspace between the felt and insulation. I can only put in what fits.

 

[endecotp]

Why are you insulating at rafter level, rather than at loft floor level?

 

[MarkSSL]

Why are you insulating at rafter level, rather than at loft floor level?

I’m doing a vaulted ceiling and leaving the A frames and purlins exposed. So 2m from walls to second purlin then horizontal 2m centre.

 

[freddiemercurystwin]

So why is there a headroom problem?

 

[MarkSSL]

So why is there a headroom problem?

The existing rafter ends come down quite low where they meet the walls as it is. If I increase the depth much more I’ll lose the headroom.
If headroom wasn’t an issue what size timber would you suggest I add to take thicker insulation?
Thanks

 

[freddiemercurystwin]

If this an upgrade and not subject to Building Control then 50mm celotex between and then a continuous 25mm layer beneath, no need for any battens. Not ideal but better than a kick in the Nads!

 

[MarkSSL]

Great thanks. No we’re not bound by regs as it’s just a refurb. We have checked with the council. However we want to do it as close to regs as poss. Do you mean a continuous 25mm of celotex?

 

[MarkSSL]

Can I use Isover roll instead of celotex?

 

[endecotp]

Isover is a mineral wool material; it has about half the thermal performance of a board like celotex for the same thickness. On the other hand it will be better at absorbing sound, and lets moisture through.

If you want the most thermal benefit with thr least loss of headroom, celotex or equivalent would be a better choice.

 

[Ian H]

Do you mean a continuous 25mm of celotex?

He means like this:

Some between the rafters (rafters are covered with foil tape there), then a full layer under them.

 

[MarkSSL]

The breathable wool is preferable for that very reason. Also it’s a holiday cottage so it will be empty for periods with no heat.
Thanks for the advice