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How to use a foam gun for insulation...

T

TrimTheKing

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One for Mike mainly, but anyone who knows...

I've been finding the cutting and fitting of 4" Celotex to fit between my rafters a right ballache and recall Mike saying he cut it shy then filled the gaps with foam using a gun for better control.

So I've got my insulation, bought me a gun, 2 cans of foam and a can of cleaner and am ready to go, but I haven't a Scooby what I'm doing...

Prior to purchasing the gun etc.I have been trying to cut my insulation with a slight bevel to the edges so as I push it in it tightens but this is hit and miss as the slightest slip with the saw makes it too loose that it falls out or too wide and it's impossible to push in.

I'm assuming I should be cutting it with a bevel to both edges with the wide face just the width of the rafter gap so it's snugly held in, then fill the beveled gaps which would be about 10mm at the rafter edge, with foam.

Can anyone confirm if this is correct and if so describe or show me the best technique for doing it. If that's not how to do it then the same request, please teach me...!

Cheers
Mark
 
There is no good technique. No way that this job is ever anything other than unpleasant. I found that I used lots of wedges. Offer the undersized piece of Celotex up, push in 3 or 4 wedges, spray the foam around, then the following day take the wedges out and foam up the holes they leave. I experimented with using Celotex for the wedges, with mixed results.

I found that cutting a taper and offering the wider side in first gave me the best chance with a foam gun. Builders do it the other way around, so that they can hide the poor fit, and do the job quicker, using less foam. I also developed a technique of stabbing the end of the gun into small gaps and squirting as I withdrew it.
 
Have not done too much celotex PU.... But can comment on the cleaner.

Used a gun loads on my build. I also bought gun cleaner, and have yet to crack it open. You're​ better off keeping a tin of foam on the gun at all times, pick the blob off the end when you're ready to use, open the needle valve and squirt away. When your done close off the needle tight and store upright (I believe is the advice).

I got my gun out the other week for the first time this year, had a part used can on it... picked off the blob, opened the valve and off I went...


The cleaner is still sealed on the shelf. If anything the cleaner might stitch you up if you don't do a sterling job with it... But why bother IMO [emoji6]



Bit off topic but HTH

There's probably a trick, but a thought on the panels, how about cut close, timber wedges to hold in place, foam. When set pull out wedges and foam the wedge holes to finish?






Jim

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I don't know how thick your insulation is but mine is 100mm. The saw blade flexes so much, it's almost impossible to get straight line.

So I GALMI. Seriously, out of the several guys onsite, one was superb...very tight and almost impossible to get any foam in...hence aluminium tape (Toolstation much cheaper than Screwfix, BTW). Then there was the young lad and he was, basically, **** at it. So many gaps. Another guy, who is also a plasterer was a bit better.

Then there is me. And I also started using a saw and found it wandering. I tried offering the stuff up and then trying to saw down so that it fitted. Crap.

Then :idea: :idea: :idea: :idea:

Festool TS55 and the track. Brilliant. Straight cuts. Stick in. Any gaps have parallel sides...give or take the vagaries of studding timber. Job done.
 
I have made similar jigs to this as a budget alternative to a rail. I can get good results with it, without the worry that the saw will wander.

116.jpg


http://www.woodworkersjournal.com/makin ... cular-saw/

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Cheers chaps. So using a tracksaw, that obviously doesn't go all the way through my 100mm boards, how do you do that? Finish the cut with handsaw or flip the board and cot from other side?

Cheers
Mark
 
Mark I used a circular saw also, very straightforward, I cut the remaining bit with a cheap handsaw, the circular saw cut keeps you on track.
 
I flip it over and cut from the other side. Usually a small lip between the two cuts but it doesn't matter.
 
I'm not sure about you ole boys! I've got the 120mm insulation and I've never had a hand saw wander. I'm quite proud of my straight cuts.
 
These might be what you are after:
https://youtu.be/mMlfmxuuPG4

I believe they're available from Toolstation but be sure to Google and shop around, I bought some from eBay a while back for much cheaper than elsewhere.

Good luck, Tony

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