What is the recommended saw/knife for cutting Knauf dri-therm insulation slabs or Woodfibre/Hemp fibre insulation slabs?

 

And do these require regular sharpening?

 

Thanks

I used really good industrial scissors. Made easy work of it.

 

Or you could use a craft knife with plenty of blades.

On big industrial jobs you see the serrated knife below, think how much insulation is used for a boiler used to generate steam for power generation… 

 

for H&S reasons as managers were never so keen but they work. 
 

At home an old bread knife usually comes out…

This works really well for Dritherm and Isover https://www.amazon.co.uk/Bahco-PC-22-INS-22-inch-Insulation-Saw/dp/B003Y3SJMG the deep blade makes it easier to cut square. Compressing the batt with a plank on top helps too.

 

Not tried it for woodfibre but have used a fine toothed handsaw which cuts really well. Lots of dust released doing this so wear a mask

I take it you are talking flexi WF? I found a handsaw and, as per @torre, compression, worked well. For rigid WF Pavatex sell a blade for a reciprocating saw but TBH it was not a success for me. Circular saw with dust extraction worked for rigid WF. 2 passes - one from each side - for thicker sheets.

From experience hemp is good to work with but really tough to cut - a toothed blade is impossible.

 

If you're doing a small quantity, then you can get away with the Bacho Profcut PC-22-INS insulation saw, though it works works better with normal insulation (EPS, XPS, etc).

 

For larger quantities of hemp or woodfibre, it's essential to invest in an electric saw with wavy-edged blades, which make it almost as easy as cutting butter. I only know of 2, but there must be others:

• Bosch Professional GFZ 16-35 AC + the TF350WM blades (I got through 2 pairs) - demo if you look for the video at https://www.bosch-professional.com/fr/fr/lame-de-scie-tandem-pro-fibre-insulation-tf350wm-3053403-ocs-ac/.
• Festool 577231 18V cordless

You may pick one up on eBay, as I did.

 

Edited April 5, 20251 yr by Mike

Excellent suggestions. Much appreciated. Have settled on Bahco insulation saw  and also will be ordering the saw sharpener at the same time and Hultafors mineral knife.

 

As primarily will be cutting Knauf Dritherm 32 insulation slabs I think the above will suffice.

 

Next topic is choice of PPE to protect the lungs.

 

Need something that'll allow for protection + ventilation at the same time.

Have started a new thread.

 

4 hours ago, ab12 said:

As primarily will be cutting Knauf Dritherm 32 insulation slabs

FWIW, I avoid using glassfibre now;  it's not much fun to work with, even with a respirator & gloves.