Cold Garage - Foil insulation and wall sealer??

[Fred101]

Hi All,

I have an attached garage that has an 8m single block (100mm thick) and render external wall and a couple of similar build returns either side of a 45mm thick insulated up and over panel door. The other 2 walls are attached the main body of the house.
In winter the garage is almost too cold to use and so I'm part way through an insulation project. I don't need it to be like a lounge, but just a reasonably insulated workshop and gym area where I can be comfortable and not freeze my bits off
So far I've insulated the loft floor above the garage with approx 150mm of fibre insulation roll, with 25mm chipboard on top. Now I need to sort the external walls and have been looking at a foil based solution...something like a YBS SuperQuilt (space saving, easier to install and less mess??). I'm told that with an air gap either side its about the same as 80mm of PIR. I'd be really interested to know if anyone has used this (or any equivalent) and whether there are any tips/tricks and what you thought of the outcome?
Additionally I am getting a bit of damp coming through the wall and so wondering if I should seal the inside of the wall first with something like a Flexiseal 'paint'?

Thanks,
Fred.

 

[sxturbo]

From what I've heard the super quilt stuff isn't that great.

 

[^woody^]

Don't believe the hype. Foil quilts don't work on their own, or as good as claimed.

In any case, they need an air cavity either side so not as space saving as you think, and not as good as the equivalent thickness of PIR.

 

[Fred101]

Hi Woody,

Thanks for the feedback and having never used foil before, I am wary. The product I was looking at would be a 90mm thick install (2x25mm air gap plus a 40mm thick foil) and I have asked the supplier for their technical data to show how that compares against 75mm and 100mm PIR installations.

 

[^woody^]

65-70mm of Celotex or similar will meet correct building regulations.

 

[catlad]

Build a timber stud wall and insulate with celotex or similar if you want it to keep heat in.

 

[Fred101]

Thanks for the tips folks
I also got the feedback from the suppliers. Their 40mm blanket +~20mm air gap either side means an 80mmm installation and that is equivalent to about 80-85mm of PIR. So in fact there is very little in it from a heat loss and size perspective, but this comparison is based on unbroken sheets of Cellotex being used i.e. no cross bracing (no batten thermal bridge losses). If you had a set up where there was any cross bracing which meant having to cut the Celotex sheets then the blanket would actually do a better job according to the stats.

 

[oldbutnotdead]

Not sure how the price of the foils compares with rigid insulation.
For a garage (assuming you arent't going to hang cupboards etc on the walls) you can batten (slate battens up the walls) then fix yr celotex to them. Or glue the celotex direct to the walls.
The foil plus air gaps presumably relies on the air in the gaps being static (ie no chinks in the blockwork for draughts, no penetrations on the room side for sockets etc...)
One other (very cost-effective but slightly more space consuming) method is to build your stud wall, fill the gaps with 100mm rockwool then fix 25mm celotex to the surface (eliminates the thermal bridges). Much easier getting rockwool draughtproof, cutting pir to exact sizes is very boring

 

[^woody^]

www.diynot.com/diy/threads/boarding-garage-walls.527015/#post-4422017

Post #4 and otters, how to batten avoid thermal bridging with PIR

 

[Fred101]

"One other (very cost-effective but slightly more space consuming) method is to build your stud wall, fill the gaps with 100mm rockwool then fix 25mm celotex to the surface (eliminates the thermal bridges). Much easier getting rockwool draughtproof, cutting pir to exact sizes is very boring"

Thanks for the feedback. Presumably I would need a VPL between the rockwool and brickwork and as for finishing the exposed Celotex face inside the garage, I'm guessing that just screwing plasterboard through it and into the battens would be the idea...or of course using an insulated plasterboard to the same effect?