Cutting solid insulation?

[ssray]

I have to cut some celotex type insulation of up to 150mm thick, this is to replace the rock wool in the loft and put some(100mm) under the roof, it took ages to do under the house because my father in law was cutting with a handsaw, any ideas what i could use that wont cost an arm and a leg?
I thought a bout a hot wire but the stuff is probably too thick.
Ray

[Fatboy]

I've not tried it on 150mm celotex, but on 50mm I cut one side with a sharp knife then just cracked it across, then cut the foil on the other side - very quick, but 150mm might be too thick - worthe try though?

[Ricky_M]

It works with plasterboard worth a go. Score it using a straight edge and stanley, karate chop and slice the foil on the other side.

If that doesn't work, saw faster!

[Globulator]

Ricky_M said:

It works with plasterboard worth a go. Score it using a straight edge and stanley, karate chop and slice the foil on the other side.

If that doesn't work, saw faster!

Kung fu chops also work.
Don't use lamb.

[TooLateForAName]

I'd score it with a steel rule and a decent sized knife. Thinner stuff (up to 50mm) I've cut with an old breadknife.

It does blunt knives very quickly so have a stone handy to keep sharp.

[Driller]

250mm angle grinder works a treat.

[MrV]

You could get yourself a cheap reciprocating saw.

[Hedders]

A handsaw is probably as fast a way to cut it as you will find but cutting it with a knife saves a lot of clean up time.

[andy43]

Stanley knife method like on plasterboard works ok on thinner stuff - on 150mm it'd be the quickest method but the cut edges would be all over the place as it doesn't break cleanly - you could always foam any gaps afterwards.
Handsaw is the easiest and most accurate for thicker stuff - just cut along a straight edge.
Bear in mind the amount of 'orrible dust created using a mechanical saw or angle grinder would be ridiculous.

[SXi Lad]

Jig saw....if you have one.

[Hedders]

SXi Lad said:

Jig saw....if you have one.

I have never seen a jig saw with 6" of cutting blade!

[SXi Lad]

Hedders said:

SXi Lad said:

Jig saw....if you have one.

I have never seen a jig saw with 6" of cutting blade!

This?Edited :woops...thought he was after something 100mm long to cut.

Edited by SXi Lad on Monday 9th August 13:19

[Hedders]

SXi Lad said:

Hedders said:

SXi Lad said:

Jig saw....if you have one.

I have never seen a jig saw with 6" of cutting blade!

This?

That is 66mm!

Edited by Hedders on Monday 9th August 13:19

[herbialfa]

Go to B & Q buy yourself a decent hand saw and a big black felt inky!

Cut to the line job done!

Yes there will be a lot of particles breaking off, but if you are doing it in the loft the particles are falling/ can be swept to where they are intended!

[Gareth79]

Electric carving knife perhaps?

[B17NNS]

I'd have thought a course bladed handsaw is the best option.

http://www.screwfix.com/prods/38309/Hand-Tools/For...

[ssray]

I used a hand saw last time(rather poor father in law did) lots of dust and mess, that concrete saw looks ok may get 2 just to see.
cheers
Ray

[Driller]

Driller said:

250mm angle grinder works a treat.

This wasn't a joke. I cut a whole bunch of 200mm thick cotton insulation with a metal disc cutter blade and it goes through like a knife through butter.

Trying to cut with a knife or jigsaw takes ages and doesn't give a clean cut.