PIR Insulation fitting
Discussion
I'm about to start PIR insulating a vaulted roof with PIR board. Will leave the required gap and all that, don't worry. I've done this before and generally used a wood saw to cut up the boards - it's pretty quick and easy. A couple of things are a bit painful though, and I wondered how other people have done this:
1) When you but the board, and it happens that you but it just a tiny bit oversize trying to get a snug fit, it's seemingly impossible to trim it down to size without making a right mess of the edge of the board. I'd use a circular saw, but mine hasn't got that kind of depth. I can't find a 'PIR board plane' or similar - do they exist at all?
2) Cutting notches for where (say) bolts are holding double rafters together and you need to get the board past the nut head is very painful - anyone got tips for how you quickly accomplish this?
Cheers
1) When you but the board, and it happens that you but it just a tiny bit oversize trying to get a snug fit, it's seemingly impossible to trim it down to size without making a right mess of the edge of the board. I'd use a circular saw, but mine hasn't got that kind of depth. I can't find a 'PIR board plane' or similar - do they exist at all?
2) Cutting notches for where (say) bolts are holding double rafters together and you need to get the board past the nut head is very painful - anyone got tips for how you quickly accomplish this?
Cheers
A long sharp kitchen knife is handy.
Shave off slivers, as said above taper it a bit and bash it in.
I found a template that was about an inch too small was useful, each piece could be measured as 'template plus Xmm' at each end.
If a piece doesn't fit the intended hole, try it in other holes!
Shave off slivers, as said above taper it a bit and bash it in.
I found a template that was about an inch too small was useful, each piece could be measured as 'template plus Xmm' at each end.
If a piece doesn't fit the intended hole, try it in other holes!
I know what a tedious job cutting PIR to fit between rafters is. The easier but more expensive way these days is to use 'Gapo Tape' all around the board. You cut the boards slightly undersize and the foam tape conforms to all the gaps and irregularities between the rafters and gives a much better fit and higher performance install.
I hadn't heard of it when I was doing my roof, so just had to measure and cut to the specific aperture and fill any gaps with expanding foam.
There are insulation specific saws with a wavy blade that slice through without making any dust, also available for jigsaws. They can wander a bit so you have to be careful how you guide the blade to achieve a straight cut.
I hadn't heard of it when I was doing my roof, so just had to measure and cut to the specific aperture and fill any gaps with expanding foam.
There are insulation specific saws with a wavy blade that slice through without making any dust, also available for jigsaws. They can wander a bit so you have to be careful how you guide the blade to achieve a straight cut.
For point 1), one of these - https://www.toolstation.com/stanley-surform-plasti...
On point 2) sharp snap off knife with blade fully extended to use required length - https://www.toolstation.com/minotaur-snap-off-knif...
On point 2) sharp snap off knife with blade fully extended to use required length - https://www.toolstation.com/minotaur-snap-off-knif...
The technique I used was to mark and cut through the foil on both sides, then running the insulation saw carefully along the cut line with the foil guiding the blade to ensure it was running perpendicularly. Obvious it can wander and start cutting through the foil if you're not careful, but it does help to some extent.
Cutting PIR board on site for decades now, it certainly helps if you put it in from scaffold level before it’s felted and battened.
We just use an old wood saw, taper your edges a bit to get a snug fit, when knocking into place an off cut of timber like 4x1 is handy as when you hit it it will not split the board which can happen if it’s a very tight fit.
Mask up, maybe goggles as well as it’s nasty stuff in your mincers.
If you’ve got a foam gun handy, that’s good for cuts with gaps, also helps hold in situ but usually we just tosh nail a couple of 3 inch galvs to hold it in.
Festool do a pir saw as you’d expect.
https://www.screwfix.com/p/festool-isc-240-eb-basi...
We just use an old wood saw, taper your edges a bit to get a snug fit, when knocking into place an off cut of timber like 4x1 is handy as when you hit it it will not split the board which can happen if it’s a very tight fit.
Mask up, maybe goggles as well as it’s nasty stuff in your mincers.
If you’ve got a foam gun handy, that’s good for cuts with gaps, also helps hold in situ but usually we just tosh nail a couple of 3 inch galvs to hold it in.
Festool do a pir saw as you’d expect.
https://www.screwfix.com/p/festool-isc-240-eb-basi...
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