Yet Another Cycling Forum
General Category => The Knowledge => OT Knowledge => Topic started by: Wombat on 01 February, 2018, 06:14:48 pm
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Has anyone here experience of cutting a significant number of Kingspan insulation boards? I intend to use such stuff for my new workshop which will be timber studding at 600mm centres, and the boards are supplied in 2400x1200, as per usual. Their suggestion is to use a fine toothed saw, but the issue is making a decent straight cut that is definitely vertical. Their other suggest doesn't sound too clever for a 90mm thick board, namely scoring one side and snapping it over a straightedge. At £53 a sheet, I'm not keen on this!
Unless anyone can suggest anything better, I think I'm resigned to cutting all 15 or so boards down the middle by clamping a straightedge in place and then using a handsaw being very careful to keep it vertical.
For info, I don't have a table saw, and have no intention of buying one, (I've got a reasonable chopsaw for general timber cutting, and a crappy B&D circular saw)
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I run a circular saw along the factory edge of a sheet of ply.
Don't forget dust mask, googles and ear defenders and allow for the kerf.
Like this @ 2:05.... https://www.youtube.com/watch?v=j_0fFH0Hm_M
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Is this just insulation or plasterboard backed insulation? I had best success cutting celotex with a bread knife!
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I used a Japanese knife from Axminster Tools which was, in fact, very much like a bread-knife.
https://www.axminster.co.uk/insulation-cutter-502386
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A sharp carving knife will do it too.
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Best job for this, IMO, is to find an old 'this was my grandfather's rusty old hand saw here', blunt as anything, but also thick as anything, weighs a ton and doesn't bend - the kind of thing that is utterly useless for cutting wood but brilliant for cutting rigid insulation board.
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Did loads of 50mm Celotex for my roof using a kitchen knife. Sawing makes a lot more mess. For 90mm I guess you could cut from both sides and snap it. Celotex has gridlines which help but aren't precisely centred. And of course you will be taping the joins. I liked that bit.
Also found that my supplier was selling 25mm for less than half the price of 50mm :smug: Was able to overlap joins and get a better TOG value.
If you do use a hand saw, they are very cheap and effective these days. Also deadly sharp.
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My Stanley Jet Cut hand saw was very good but it shed a load of mess. The bread knife was just about long enough for 100mm celotex and made very little mess indeed.
The multiple layers of 50mm is a sound idea and one I'll be using if I ever do a similar job again. Much easier to handle.
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You should be able to do a reasonably straight job in my experience using a hand saw. If the edge tapers slightly it makes it easier to fit in the hole but like me I'm sure you'd want to ensure a proper insulation job with no air gaps to allow cold bridges.
I find most new hand saws run pretty straight (I've had the odd one that doesn't) but where they get knocked about the teeth lose their proper alignment and it becomes impossible to saw anything straight. In the old days you'd re-sharpen your saw and re-set the teeth angle, but these days you buy a new hardpoint saw for a tenner. :(
If you have a convenient helper to hold the board in place you can sometimes successfully run the saw down the side of the timber studding (if it's 4 x 2 that gives a good flat surface to keep the saw blade straight. You can then directly saw the board to fit the hole keeping the edge nice and straight. In theory.. Good luck!
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Hand saws are dead easy to sharpen and set, plus they last a lifetime.
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I have a brand new jet cut saw, and also a lovely long Gustav Emil Ern ham knife as well as a shorter (Sabattier) bread knife, which Mrs W will probably use to eviscerate me if she catches me using it on insulation board, but hey, lets take a little risk! It is just foam, with a very thin foil layer on each side. there will not generally be joins, as each bit is supposed to fit tightly between vertical timber studs. I need my workshop to be well insulated, as paying lots to heat it is a no-no. We haven't even moved in yet (Monday) and I've already placed the order for the solar PV installation, which starts 2 days after we move in!
My circular saw isn't deep enough to do the cut in one go.
Talking of "taking a little risk", it seems I have to travel to Sierra Leone again later this month, and there is some violence in the capital, Freetown, prior to their elections. Ho hum, the things I do for charity... I hope I get back to build this workshop!
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Hand saws are dead easy to sharpen and set, plus they last a lifetime.
So do Tom Tom updates!
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My circular saw isn't deep enough to do the cut in one go.
You have to flip it over and cut on both sides. It makes a lot of dust, but it's quick and precise. Is your framing square and parallel ?
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Is the dust ok or would a mask be a good plan?
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The dust is very much not ok.
Your body isn't able to process it, once it has been ingested / inhaled.
Wear a mask, and ensure that it is a decent one which seals against your face.
ETA - I note with interest, that Kingspan advise that masks are not required.
I'm inclined to err on the side of caution.
Next thing, they'll be telling you it is ok to put it in your tea....
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As Jurek says, a mask is necessary even if you cut it with a hand saw. It's grim stuff and a vacuum attached to the circular saw is also advisable.
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I've got a decent mask, a proper one with a choice of replaceable filters, that fits properly.
I haven't started building it yet, on account of not having moved in yet. Move in date is Monday, but the vendors emailed the estate agent to say they'd moved out a couple of days ago, so we went up there today, to deposit a few plants in big pots round the back, and to measure the barn for the workshop. However, as we approached, there were two removal vans in the drive, and some dickhead had parked a 4x4 on the otherwise nice grass verge. Bastards, keeping up the lying, right to the bitter end. I'll ask the estate agent on Monday, when I collect the keys, if they have dropped some in to them since Saturday afternoon (they close at 1300 Saturday). If not, then I'll be instructing my solicitor to reclaim the cost of changing ALL the locks from them.
I was going to change them for better quality ones anyway, but not returning all the keys is downright bloody fraudulent. We shall see.
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What a weird house buying experience you're having.
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I've got a decent mask, a proper one with a choice of replaceable filters, that fits properly.
I haven't started building it yet, on account of not having moved in yet. Move in date is Monday, but the vendors emailed the estate agent to say they'd moved out a couple of days ago, so we went up there today, to deposit a few plants in big pots round the back, and to measure the barn for the workshop. However, as we approached, there were two removal vans in the drive, and some dickhead had parked a 4x4 on the otherwise nice grass verge. Bastards, keeping up the lying, right to the bitter end. I'll ask the estate agent on Monday, when I collect the keys, if they have dropped some in to them since Saturday afternoon (they close at 1300 Saturday). If not, then I'll be instructing my solicitor to reclaim the cost of changing ALL the locks from them.
I was going to change them for better quality ones anyway, but not returning all the keys is downright bloody fraudulent. We shall see.
Have always changed the locks on moving in.
Used to really piss off the landlord.
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Score and break works well.
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cutting all 15 or so boards down the middle by clamping a straightedge in place and then using a handsaw being very careful to keep it vertical.
If some cuts don't end up vertical, or just to get a better seal around the insulation panels, consider applying a light bead of expanding foam sealant around the perimeter immediately before placing panels between the studs.
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Score and break works well.
Yes, the material has no grain to make the break irregular altho' the cut should be as deep as possible. It's not too hard to achieve a vertical cut - I used a tin can as a check.