Accurate cutting of PIR insulation.

[Zedheadsteve]

Sorry, more a of a construction topic than woodwork. Any recommendations for fitting PIR insulation? I have successfully used a small Dewalt site table saw to fit a little 100mm PIR very square and snuggly to joist and stud work. I cannot personally do this as well with a hand saw or knife type blade. Trouble is of course, the site saw or a circular saw generates lots of nasty dust. Need to do this outside and with really good mask and goggles, but still not happy in terms of environment or health.

Anyone tried the Festool 240 with extraction?

Steve

 

[SammyQ]

Steve, '40tonne wrecking ball to shell a peanut' occurs to me? Are you seriously SO far out when you use a disposable 'hardpoint' that a slightly oversize square of PIR doesn't squash fit? A similar shaped, but slightly smaller, ply offcut and a rubber mallet are also handy for persuasion into the desired compartment. On the odd occasion that I boo-boo and cut short, a 1-second squirt of expanding foam, time, and said hardpoint to trim flush, have proved more than adequate.

Hoping I have not missed something obvious, Sam.

 

[johnnyb]

we have a great system. we use a track saw with a 3m rail. coarse blade with slowest speed and extraction. it wont go right through 100 but it makes easy accirate cuts. cut from both sides and finish with a saw. our cuts are nearly perfect fit.

 

[johnnyb]

also knock in with a lead dressing tool.

 

[johnnyb]

anyone whose fitted lots of this knows its not a job for a hardpoint saw and dodgy cuts. remember most roofs need 6 or 7 inch of this!
personally only the apprentice does it by hand.

 

[MikeG.]

..........or cut it undersize, wedge it into place, and use expanding foam to fill all round.

The idea that the Celotex has to be cut dead square is amusing, considering how twisted the timbers will be that it's fitted to. And of course all those joists or rafters will be dead straight and parallel, won't they.

 

[Deadeye]

Sorry, more a of a construction topic than woodwork. Any recommendations for fitting PIR insulation? I have successfully used a small Dewalt site table saw to fit a little 100mm PIR very square and snuggly to joist and stud work. I cannot personally do this as well with a hand saw or knife type blade. Trouble is of course, the site saw or a circular saw generates lots of nasty dust. Need to do this outside and with really good mask and goggles, but still not happy in terms of environment or health.

Anyone tried the Festool 240 with extraction?

Steve

Just before I got put out of commission by surgery I insulated my workshoip (garage) ceiling. The joists were neither evenly spaced nor parallel, and there were random bits of electric/bracing and pillar to work round. The above sums up the approach exactly. I'm not great with foam, but I don't think I have lost many conductance points.

 

[SammyQ]

Johnnyb? Not all of us are 'in the trade' with all the toys or have deep enough pockets to afford the Male Festeringtool Jewellry...
Speaking as a time-served and indented amateur, the two houses I renovated/insulated were well served by a hardpoint and careful laying out.
Gotta say though, that feckin polymacstyrene 'bobble' dust gets everywhere :shock: and sticks to everything ! Good extraction, humble vacuum, both are a God-send!
Sam, now a convert to Kingspan.

 

[Lons]

About 12 years ago when I fitted well over 100 8x4 sheets during a stable conversion. tried the handsaw but dust was horrible so bought some cheap semi flexible, thin bread knives and we cut the lot with those using straightedges. It was so effective I used them ever since.
Only modification was to wrap the knife handles with foam for comfort.

 

[Trevanion]

thin bread knives and we cut the lot with those using straightedges. It was so effective I used them ever since.

I think you can buy proper insulation handsaws that are basically a longer bread knife :lol: No teeth just a wavy (serrated? not too sure) edge. I imagine there's barely any dust with one of those.

It really depends on how much you've got to put in, if you've only got 100 sheets to do or so you'd be an ***** to think about buying anything more than a handsaw to cut it up. If you're planning on putting in tens of thousands of sheets over years and years and that's your only job perhaps it's worth investing the money in some shiny green nonsense but everyone I've ever seen on site will always cut it in with a hand saw because it's quick and cheap. By the time you set up a cut with one of those Festool jobbies, I wouldn't be surprised if some people I know would've already done a wall by the time you've finished the cut.

 

[Doug71]

we have a great system. we use a track saw with a 3m rail. coarse blade with slowest speed and extraction. it wont go right through 100 but it makes easy accirate cuts. cut from both sides and finish with a saw. our cuts are nearly perfect fit.

Johnnyb? Not all of us are 'in the trade' with all the toys or have deep enough pockets to afford the Male Festeringtool Jewellry...
Speaking as a time-served and indented amateur, the two houses I renovated/insulated were well served by a hardpoint and careful laying out.
Gotta say though, that feckin polymacstyrene 'bobble' dust gets everywhere :shock: and sticks to everything ! Good extraction, humble vacuum, both are a God-send!
Sam, now a convert to Kingspan.

The Festool tracksaw is the cheap option, this is the proper tool for the job

https://www.kelvinpowertools.com/festoo ... gItGPD_BwE

 

[Lons]

It really depends on how much you've got to put in, if you've only got 100 sheets to do or so you'd be an ***** to think about buying anything more than a handsaw to cut it up. If you're planning on putting in tens of thousands of sheets over years and years and that's your only job perhaps it's worth investing the money in some shiny green nonsense but everyone I've ever seen on site will always cut it in with a hand saw because it's quick and cheap.

The 100 odd sheets felt like 1000s at the time, I assure you. :lol: :lol:

 

[johnnyb]

wow i never expected any annoyance from my response! anyway i use makita! if youve got 20 100mm sheets and own a track saw and a vac buy the 3m rail its well worth it.100mm sheets wont cut with a bread knife or a celotex saw. its to deep.
any joiner thats going to be doing the insulation will make sure his joists are evenly spaced. as a job cutting insulation is dreadful cutting a house size amount is really dreadful.
we write the size on the adjacent joist top and bottom. cut exact size. 80% it goes in 20% in needs adjusting. its satisfying as well getting a really good fit. ok some caveats a fast wood circular saw can and will bind. a table saw is worse . most dust gets in your eyes when your knocking in. accurate cutting helps hugely.
btw this tip is a product of experience...take it or leave it but those insulation saws by festool are really meant for bats not pir.yes they make a special blade but the concept is for bats.slow blade speed on the track saw is the key.

 

[johnnyb]

also 100 sheets of 100mm kingspan would be what £4000-5000. a few weeks worth of work fitting. not really a small amount tbh. it would be a pile 10m high.

 

[Zedheadsteve]

Yes the material costs are v. high compared to the tools. If they makes the job better and especially quicker then they tend to pay for themselves. Producing scrap or not doing stuff right first time is just pure waste.

 

[SammyQ]

"wow i never expected any annoyance from my response!"

No annoyance generated or umbrage taken Johnny, just gently pointing out some of us forumites are not in the trade and don't have the tools to diversify sideways into cutting Celotex/Kingspan. Or, the 'greenbacks' (that shows my age) to swank a Cesspool, sorry, Festool, wotsit. Nae probs Big Lad.

Bob? Did you REALLY cut all those sheets by hand? You must have looked like a teddy bear at each day's end...respect.

Sam

 

[MikeG.]

wow i never expected any annoyance from my response!.......

You didn't get any. Don't confuse people having a different opinion from you with people being annoyed with you. There's usually a dozen different ways to skin any particular cat, and someone choosing a different way from you doesn't imply that yours is wrong, or that there is any emotional attachment to the discussion about cat skinning.

 

[SammyQ]

Wot Mike said. Better than I did.

Sam

 

[johnnyb]

i can see that now guys.

 

[Jacob]

..........or cut it undersize, wedge it into place, and use expanding foam to fill all round.

The idea that the Celotex has to be cut dead square is amusing, considering how twisted the timbers will be that it's fitted to. And of course all those joists or rafters will be dead straight and parallel, won't they.

Yep. Even if you cut it with a precise TS it still won't fit and you have all the dust to contend with.
Done loads in the past with a lath for straightedge, a felt tip, a tape, and a panel saw - doesn't even have to be very sharp! A long surform plane thing is good for taking of bumps from the edges