PIR insulation board cutter

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Roberto2019

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I am about to start insulating an extension roof. It involves cutting a large amount of 100mm PIR insulation board.

Having cut a few bits already with a hand saw, it is very hard to get a straight line at 90 degrees all the way through.

There is a Festool PIR cutter which looks perfect for the job, but is over 500 quid.

Is anyone aware of a cheaper version that does the same thing, or a different type of tool that gets a good accurate cut?
 
I've never known anyone use anything but a hand saw, there are specific hand saws for insulation.
 
Roberto2019 said:
I am about to start insulating an extension roof. It involves cutting a large amount of 100mm PIR insulation board.

Having cut a few bits already with a hand saw, it is very hard to get a straight line at 90 degrees all the way through.

There is a Festool PIR cutter which looks perfect for the job, but is over 500 quid.

Is anyone aware of a cheaper version that does the same thing, or a different type of tool that gets a good accurate cut?
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Just use a timber straight edge and cut along it using a saw, if you want to avoid airborne fibres use one of these

Insulation Saw Bahco - ref. PC-22-INS - RUBIX UK

uk.rubix.com uk.rubix.com
 
I've also used a bread knife :oops: a lot less dust than a saw
 
Roberto2019 said:
Having cut a few bits already with a hand saw, it is very hard to get a straight line at 90 degrees all the way through.

There is a Festool PIR cutter which looks perfect for the job, but is over 500 quid.

Is anyone aware of a cheaper version that does the same thing, or a different type of tool that gets a good accurate cut?
Click to expand...
Unfortunately the Festool really is the only game in town at present. I believe the saw blade is backed by a steel guide in much the same way as a cloth cutter (and they are also in the same price league). I've only seen one insulation firm using the Festool - it was fast, clean, accurate and made bang on plumb cuts

Like @Charlie George I generally just use a Bahco insulation saw

Bahco Insulation Saw.jpg


guided by a piece of CLS. They create a lot less mess than using a hand saw with teeth but can be a bit awkward to keep sawing plumb. Doing a lot of insulation with them can be hot work (which is why we have apprentices :evil: ). They certainly cut straighter and cleaner than a bread knife.

I've also tried long jigsaw blades, like the Bosch T1013AWP:

Bosch T1013AWP Insulation Jigsaw Blade.jpg


which do work, but I found the squareness of cut depends pretty much on the quality of the jigsaw. With a Bosch jigsaw which has the extra/double blade guides (e.g. GSR135BCE, GST140BCE and GST160BCE) or the ultra rigid Maffell (P1cc) they cut fairly true, but can wander off - that's from trying them with my 15-year old old GST135BCE, a mate's GST160BCE and my current P1cc. With other jigsaws that lack the second guide (e.g my Makita DJV181) they seem a bit more hit and miss and tend to wander off from plumb a bit. They are good for mineral wool batting as well, but they do need to be run along a straight piece of plywood both to guide the cut and to prevent the base of the saw digging in or tilting. Festool make a similar blade, the S 155/EW/3
 
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Do not, DO NOT talk to me about cutting this damn stuff. The past two months have been traumatic. :sick:

Anyway, you should be able to get a straight and vertical cut with a normal hand saw. Remember there is little resistance compared to timber so don't force the saw - and you can cut on the push and pull stroke.

Use a vacuum, fan or blower to get rid of the dust and wear overalls, a mask and eye protection from that fine dust.

I've also had success with a circular saw hooked up to a vacuum.

Those specialist jigsaw blades can wander in the thicker boards, but are quite quick and low dust

And say halo to my leetle friends. These have come a bit late to the party, but will be given a go shortly
Both should cut board and quilt, and I chose the knife as its polished stainless steel so (in theory) should have low resistance in board


1654680547387.png


1654680618516.png



If you get the Bahco saw, or any similar saw for mineral wool, get the Bahco sharpener (or a cheaper basic knife sharpener which is exactly the same thing) and give the blade a quick resharpen often.
 
I used the bacho insulation saw and made a table up with timber guide top and bottom to stop wandering and get square cuts. This was with 100mm PIR, so really on the limit of the saw.

I also used gapotape which was brilliant.
 
Thanks all. A bit of food for thought.

I am planning on using gapotape as well, even though expensive but I hope will make the job a little less frustrating!

Cheers
 
Roberto2019 said:
I am planning on using gapotape as well, even though expensive but I hope will make the job a little less frustrating!
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It looks like that sort of product will become more or less mandatory in due course to meet insulation standards and air tests. So we are all going to have to get lot more accurate cutting insulation! Nice.

I've recently seen some infra-red camera footage showing the differences between poorly cut PIR, poorly cut PIR with wedges of material stuffed into the gaps, tightly cut PIR and slightly loose cut PIR with Gapotape. The Gapotape installation was noticeably better, so whilst expensive, it looks like it should more than repay the initial outlay over time in reduced energy consumption.
 
The worst stuff I've ever cut with a handsaw is some reclaimed (from refrigerated lorries) rockwool. It was 100mm and I "sliced" it into thinner 1/3 and 2/3 sheets to fill a bathroom stud wall. My saw was just about long enough and the dust was horrendous.

IMG_20211111_154308201.jpg
 
"Insulation board cutting like a pro"...

Rob the Builder :LOL:

All I can say to that is he really should make the two follow up videos, "How to get pneumoconiosis like a pro" (no dust masks) and "How to use a handsaw to cut PIR boards with two fingers missing, like a pro"...

I know people do stupid things, but most people aren't so irresponsible that they film themselves being stupid at work and then recommend it to others on YouTube. This is one reason I am highly sceptical of so many things posted on YouTube (although some are brilliant "how NOT to do it" demos). In a dingy attic I just wonder how well anyone could see a jigsaw blade like that.

Thanks (?) for sharing
 
JobAndKnock said:
"How to get pneumoconiosis like a pro"
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That was my immediate thought as well.

I'm just a DIYer and I don't do major jobs, but I still wear a mask when cutting up things that produce dust, especially dust from synthetic materials.

I want to live for many years more and I want them to be health years.
 
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