Green Building Forum - Festool ISC insulation cutting saw for woodfibre board

Festool ISC insulation cutting saw for woodfibre board

Julio — Thu, 11 Sep 2025 18:07:10 +0100

Has anyone tried the Festool ISC insulation cutting saw on solid woodfibre boards thickness approx 150mm. We have been using lots of woodfibre for years on projects, but have never found the magical way of cutting it.

- Circular saw chucks dust everywhere and not very good for them
- Reciprocating saw is hard to cut good square lines with (could maybe make a jig, but becomes quite unwieldy.
- Jigsaw with long insulation cutting blade, probably the best option, but still likes to track out and bend, not giving squarest cut.

Intrigued if anyone has tried the festool, as quite an investment..

Cheers
Jules

Festool ISC insulation cutting saw for woodfibre board

fostertom — Thu, 11 Sep 2025 18:28:23 +0100

Interesting.

"The cordless insulating-material saw is de
signed to saw flexible insulating materials
made of mineral wool (glass or stone wool) or

natural fibres (e.g. wood or hemp fibres)

as well as to saw insulating materials made of PUR/PIR
(polyurethane hard foam), polystyrene or pres
sure-resistant mineral wool.
In accordance with the intended use, only insu
lating materials with the following raw densi
ties may be machined:
Flexible natural fibres < 90 kg/m³
Flexible mineral wool < 100 kg/m³
Pressure-resistant mineral
wool
100–170 kg/m³
PUR/PIR < 36 kg/m³
Polystyrene < 45 kg/m³
The cordless insulating-material saw is not
suitable for sawing chipboard, metal, wood or
pressure-resistant insulating materials made
of natural fibres."

I guess you have to have the Festool and only Festool extraction equipment as well.

Festool ISC insulation cutting saw for woodfibre board

Julio — Thu, 11 Sep 2025 21:08:57 +0100

Hi Tom,
Thanks, that suggests that it is not appropriate for cutting the more rigid woodfibre board due to its density. It's weird because I am sure I saw somewhere that it was advertised that it could cut it, but maybe the more flexible version.
It feels like there is room in the market for a tool which does this, if woodfibre board is going to be come a more popular choice of material. In the meantime back to my idea of making a jig for the reciprocating saw then!

Festool ISC insulation cutting saw for woodfibre board

fostertom — Thu, 11 Sep 2025 22:06:54 +0100

Oh, I didn't mean to show that woodfibre boards aren't included - I'd say worth a check with suppliers or even an email to Germany.

Festool ISC insulation cutting saw for woodfibre board

sgt_woulds — Fri, 12 Sep 2025 09:23:53 +0100

Hi Julio, Tom

AS you may know, I work for one of the woodfibre companies. I've also used woodfibre on my home upgrade and know how difficult it can be to get a clean cut!

I've seen the Festool demonstrated, and used with a cutting rig, it works very well - but it is horrifically expensive to buy in the UK...

One of the problems is that all of these specialist tools need to be imported from Europe, where denser woodfibre insulation is more common. As far as I'm aware, there are no UK made equivalants.

My own company has stopped importing cutting equipment - since Brexit the courier costs are huge, and the import paperwork is difficult when you import anything with blades.

For flexible insulation, you can purchase dedicated insulation hand saws - available at Wickes and other places. Make sure you buy a blade sharpener too:

https://www.wickes.co.uk/Bahco-PC-22-INS-Profcut-Insulation-Saw---22in-550mm/p/262380

https://www.toolchimp.co.uk/bahco-insulation-saw-sharpener-sharp-ins?msclkid=12fce4c377361c53a5f882ea6ac0ee73

Even with the correct insulation hand saws, it can be hard work to cut and leaves a ragged edge on the underside of the cut; support both sides under the cut as close to the saw blade as possible to reduce tearing. Sharpen the blade regularly. Really useful for small jobs or quick adjustments, but only where a larger offcut is required. If you need to remove a slither of flex then a power saw is best.

It is much easier and neater to cut with a power saw. For flex up to 60mm I’ve used a circular saw with a cutting guide with some success. You need a blade with really widely spaced teeth to prevent binding. A tool with an extraction point that can take a hoover hose is best - the dust is very binding, so brush off the tool between cuts too. Keep the dust – it’s very useful for filling gaps.

I've got a 50 + year old open-frame Black and Decker circular saw with the widest set teeth I've ever seen on a wood blade. It cuts through like butter but has no dedicated hoover attachement - I made one using duct tape and an old milk bottle. I can only cut up to 100mm deep insulation though - I have to flip the board over and cut on both sides. The lack of an automatic blade guard means it doesn't get gummed up as much as a modern tool, but it does scare me a bit, and I have to be very mindful when using!

Over 60mm, a jigsaw with an insulation blade or other reciprocating saw is required for the deeper cuts.

Powertool options include blade bits for jigsaws & sabresaws:

https://www.amazon.co.uk/Bosch-Professional-2608667396-Jigsaw-Blade/dp/B00D5YVNEA/ref=asc_df_B00D5YVNEA?tag=bingshoppinga-21&linkCode=df0&hvadid=80814161489237&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584413736787715&th=1

https://www.toolstation.com/bosch-sabre-saw-blade-precision-fibre-insulation-s013awp/p35192

Or more expensive power tool options for those with very deep pockets:

https://www.kelvinpowertools.com/festool-isc-240-18v-insulation-saw-2x-4ah-high-power-c-395-p-37058

https://www.screwfix.com/p/festool-isc-240-eb-basic-18v-li-ion-brushless-cordless-insulation-saw-bare/234HA?kpid=234HA&gclid=4c2af35771441cded06196d5d3d87f00&gclsrc=3p.ds&ds_rl=1241687&ds_rl=1245250&ds_rl=1244066&msclkid=4c2af35771441cded06196d5d3d87f00&utm_source=bing&utm_medium=cpc&utm_campaign=MPX_UK_SHP_MAN_S_ALL_Tools&utm_term=4584482474714527&utm_content=All%20-%20Tools

https://www.thesawcentre.co.uk/mafell-dss300-insulation-saw-110v.html

Unfortunately I haven't come accross any dedicated circular saw blades in the UK. I know a couple of Hungarian installers that use these, but they've had to bring them back in their luggage when they visit home:

https://www.kaindl.de/en/kaindl-insucutr-dammstoffmesser-kreismesser-o-160-350mm

The only cutting jig I've come found in the UK is this one:

https://www.roofgiant.com/misc-tools-accessories/edma-cutting-table-for-bio-based-insulation-materials/

I did start drawing up some plans to make my own cutting rig out of plywood and unistrut, to mount a jigsaw or sabre saw. But in the end, I didn't bother, as I didn't have a huge amount of cutting to do. I can see this being very useful for contractors though.

Please note that these links are all suggestions from a quick Google search rather than recommendations of retailers – buyer beware. Quite often these tools are listed as available, you order, then find out there is a 6 week wait for them to import. At the end of which, they'll tell you 'it has not been possible to fulfil the order'.

Brexit Britain - oh the freedom!

If you do come across any good options, please share them so I can pass them on to our customers...

Festool ISC insulation cutting saw for woodfibre board

Nick Parsons — Fri, 12 Sep 2025 11:09:30 +0100

I find it odd that the Festool claims it can cut ''Pressure-resistant mineral
wool
100–170 kg/m³'' while its use is not approved for cutting WF @ 140-180kg/m3.

When we did our EWI with 160mm WF I had my wood-worker friend make up a jig to clamp around the sheets so we could just run down 1 side, turn the sheet (c25kg, but OK if you say it quickly!) run down the other and finish off with a hand-saw. The jig was particularly for 'retrofit participants' not used to using WF. After the first day we gave up and did it by eye (and a line, of course!) as most of us always had.

I had bought a couple of 'Pavatex' recip saw blades designed for WF but my general experience with recip saws is that while you know where the blade goes in you have no idea where it will come out! Such is the 'flex' that you can have a pretty straight line on the 'entry side' and a wavy line the other side of the 'work'!

For cutting flex WF I find the best way, if I need accuracy, is to clamp it between two pieces of timber and cut through the compressed part.

Festool ISC insulation cutting saw for woodfibre board

Artiglio — Fri, 12 Sep 2025 11:32:19 +0100

I cut the majority of mine either by hand or using a table saw i have in the workshop, certainly better cuts but lots of walking back and forth.
If you have the space something like this and a simple diy extended infeed /outfeed table. Buy something a bit better quality and you have a very handy tool for many tasks

https://cpc.farnell.com/tigren/08210/315mm-12contractors-table-saw/dp/SI19991?mckv=sshopping_dc%7Cpcrid%7C718093598815%7Ckword%7C%7Cmatch%7C%7Cplid%7C%7Cslid%7C%7Cproduct%7CSI19991%7Cpgrid%7C169433988419%7Cptaid%7Cpla-2304038402284%7C&CMP=KNC-GUK-CPC-SHOPPING-9262013734-169433988419-SI19991&s_kwcid=AL!5616!3!718093598815!!!network%7D!2304038402284!&gad_source=1&gad_campaignid=9262013734&gbraid=0AAAAAD_m6B3OwaAjERkfUczTvDtLYcLqU&gclid=EAIaIQobChMIxLDD0oHTjwMVvZxQBh1ZSADbEAQYASABEgIAN_D_BwE

You may not be able to work round it in the space you’re doing , but in the adjacent room and you’re good to go, add on some sort of cheapish dust extraction and life gets much easier.

Festool ISC insulation cutting saw for woodfibre board

earth bau — Sun, 14 Sep 2025 07:03:38 +0100

No, unfortunately the Festool ISC won't cut the rigid wood fibre boards. It will cut the flexible wood fibre up to 300mm, like Steico Flex, for example.

Here's a Festool video showing the differet options for cutting wood fibre of different sizes and types.

https://youtu.be/DTLO2Elf-e4?si=0wDk3q9ZQJKzibrn

For 150mm you can either use a sword saw, an aligator saw, or a circular saw and cut both sides.

My initial set up was a circular saw and a hoover and this worked really well up to 60mm. My hoover was undersized at 10l capacity and I had to empty it often through out the day. If I didn't do this is in time it would get clogged up.

I've more recently being working on EWI and therefore thicker boards, and so I have upgraded to a sword saw and a hoover with a preseperator, as in the video.

The sword saw is a bit cumbersome and maybe a better arrangement is a aligator saw on a cutting rack like they show in the video, but in which they are using the ISC to cut flexible wood fibre.

Also shown here:
https://youtu.be/piKlrQ6Ps-M?si=j4-1s0t5lgeRCOox

These are all expensive options, and only worth it if you do a lot of wood fibre.

Festool ISC insulation cutting saw for woodfibre board

fostertom — Sun, 14 Sep 2025 09:15:31 +0100

Astonishing that this still is not a solved problem, after all these years. Or is somewhat for EPS but not for woodfibre.

Festool ISC insulation cutting saw for woodfibre board

Artiglio — Mon, 15 Sep 2025 07:55:14 +0100

FT , you’d have to assume that

1) the market is too small to go to the lengths of bringing a solution to market.
2) the work is getting done one way or the other anyway and so reinforces 1).
3) There is a site table saw advertised that takes a 500mm blade, not cheap and is 3 phase , so you’d likely need a convertor, plus a reasonable size waste vacuum of some sort. All in you’d be looking north of 3k, but if you did enough jobs worth the expense.
4) there are some truly huge and fearsome handheld circular saws available, a quick look shows a Mafell that goes to 185mm, but advertised price is nigh on 5k.

So solutions for builders and other professionals are out there, but few self builders are likely to go to such expense.

Festool ISC insulation cutting saw for woodfibre board

fostertom — Mon, 15 Sep 2025 11:22:43 +0100

Some portable bandsaw? That would keep the cut straight.

Festool ISC insulation cutting saw for woodfibre board

Artiglio — Mon, 15 Sep 2025 13:22:21 +0100

Portable bandsaws don’t have much of a throat depth, so you’d only be able remove relatively small strips. aquick google shows a makita version that could remove max of 244mm and has max depth of cut of 120mm. No doubt there others. If you’re using 600 wide sheets of insulation would probably do a good number of your cuts. Leaving a fewer to be done by hand.

Festool ISC insulation cutting saw for woodfibre board

stonecold — Sun, 09 Nov 2025 16:58:52 +0000

There are the Scorpion saws too, which can have the blade rotated to work like a jigsaw but I don't know how deep they cut. On 12mm plywood it is tough and wiggly lines result.

Wd had Gutex thermoflex (I think) up to 60mm thick and the Bahco Profcut Insulation Saw which is a simple handsaw was easy and did a decent job, it was the one suggested/sold by Ecological Building Systems, although we only had a limited amount of cutting to do, and we also got some Gutex loose fitt for any gaps (old house so nothing is straight). Its bizarre how expensive insulation saws are.

B&Q have some refurbished power tools, I think I saw a table saw there.

Festool ISC insulation cutting saw for woodfibre board

Artiglio — Mon, 10 Nov 2025 14:41:44 +0000

There are specialised jigsaw blades available for insulation. Sort of waveform knife edge designs. Such as this

https://www.screwfix.com/p/bosch-t313aw-soft-material-jigsaw-blades-152mm-3-pack/422FW?tc=UA4&gclsrc=aw.ds&gad_source=1&gad_campaignid=22599672207&gbraid=0AAAAAD8IdPzx7tZI3lemo0P9Us0_1RivF&gclid=EAIaIQobChMIpJXDv-fnkAMVNplQBh22YTGEEAQYASABEgKRkPD_BwE