CELOTEX TIPS AND TRICKS

[FresnoBob]

This might be a really stupid question (apologies if it is), but for the thinner thickness of Celotex, would a jigsaw do the trick?

Also what ball park price/quality of respirator to go for?

If I get some of this stuff, I might cut it at the bottom of the garden, don't fancy the kids breathing in the stuff if they happen to amble close to the work area.

 

[JohnD]

you might consider a saw which has an attachment for the hose of a vacuum cleaner to suck away the dust. My circular and jigsaws both have this.

A circular saw wil be faster and give a cleaner cut.

 

[FresnoBob]

I have a circular saw, although it's only of the bog standard Argos budget variety, it does indeed have the vacuum attachment however.

 

[mointainwalker]

Not sure which thickness you are talking about, but you can score thinner sheets witha sharp knife and snap it like plaster-board. Very clean.

 

[Norcon]

Festool ts55 on a guide rail. Then snap it back and slit with a stanley knife if its the wider stuff.
This will give you absolute accuracy. The ts75 would be better but I did my loft with a 55 and it was a doddle.
Expensive tools but you might be able to hire them.

 

[Steadi]

I think power tools and celotex are a very bad idea.... you are basically cutting expanded foam and a hand saw is far more accurate and very easy to use. Any power saw is going to mash out a far thicker blade thickness of material.

less chance of losing fingers too as full size sheets are very cumbersome, a wide, small toothed handsaw cats like a knife through butter and runs very straight.

I just bought a 3M mask from Screwfix for £20...should be adiquate and of course its a good name.

I fell foul of some cheap rubbish on Amazon last time, cost about £8 but when I finished work and looked in the mirror you could see marks on my face where the soot and celotex were sucked past the mask into my mouth.

Thats why I'm now coughing up gunk like a chain smoker, and theres bits of celotex in it.

You are probobly best to cut on site otherwise you will wear a groove through your lawn as you need to constantly measure and cut... unless of course you are on a new build where you can build the rafters into the celotex?

lets face it theres going to be dust as soon as you start fitting this stuff!
Mike

 

[Norcon]

Ive been struggling with celotex for several months

Says it all really....had my entire loft completed within two days.

 

[Steadi]

Quote, Says it all really....had my entire loft completed within two days.


Suppose so, but I'm doing two vaulted rooms with flying beams, a bathroom, the upstairs landing, a walk in wardrobe and three nasty crawl in cupboards. Plus all the surrounding stud walls on he perimeter.

Nothing is straight as the house was built in the 20's and most panels also have a hip angle to contend with.

The rafters are not parallel, warped and covered with soot as there is no roofing felt... I'm also having to crawl behind the walls that I have chosen to leave intact and cut in the Celotex. In places I can only work on my tummy its so tight.

Some time has been spent building new stud walls as the original perimiter walls were plasterboard on 11/2 by 3/4 economy batterns... Im putting in 2 by 4's, lining the back with 75mm celotex, and then filling with 100mm of my 50mm+50mm sandwhich.

All of this is being done on days off from work etc.

theres no way precut panels could be fitted without further cutting on most of every edge. Its easier for me to work with the hand saw so I can follow the wonkey guidelines.

I still think in my situation a circular saw will fill the air with dust, the handsaw cuts a very fine slot. As I said the dust is now the major problem, I'm pretty ill due to the ****e respirator as I was fitting out in those crawlspaces.

I think the original loft conversion firm did the job in too days too! ... the buggers simply diddnt bother to do the insulation and plasterboarded onto the rafters directly under the tiles.

Mike

 

[Steadi]

Quote, Says it all really....had my entire loft completed within two days.


Suppose so, but I'm doing two vaulted rooms with flying beams, a bathroom, the upstairs landing, a walk in wardrobe and three nasty crawl in cupboards. Plus all the surrounding stud walls on he perimeter.

Nothing is straight as the house was built in the 20's and most panels also have a hip angle to contend with.

The rafters are not parallel, they are badly warped and covered with soot as there is no roofing felt... I'm also having to crawl behind the walls that I have chosen to leave intact and cut in the Celotex. In places I can only work on my tummy its so tight.

Some time has been spent building new stud walls as the original perimiter walls were plasterboard on 11/2 by 3/4 economy batterns... Im putting in 2 by 4's, lining the back with 75mm celotex, and then filling with 100mm of my 50mm+50mm sandwhich.

All of this is being done on days off from work etc.

theres no way precut panels could be fitted without further cutting on most of every edge. Its easier for me to work with the hand saw so I can follow the wonkey guidelines.

I still think in my situation a circular saw will fill the air with dust, the handsaw cuts a very fine slot. As I said the dust is now the major problem, I'm pretty ill due to the s***te respirator as I was fitting out in those crawlspaces.

I think the original loft conversion firm did the job in two days too! ... the b*****r simply diddnt bother to do the insulation and plasterboarded onto the rafters directly under the tiles.

Mike

 

[Tuck1]

Floorboard saw is ideal for cellotex. Shorter and stronger than a Jack Saw, plus has teeth on its nose. Good for plastic too!

http://www.screwfix.com/p/irwin-jack-floorboard-saw-12tpi-13-330mm/30120

 

[Dutch_Diver]

Hi Mike,

I hope you are feeling better now. You mention you want to do it properly as others didn't do it right but by reading the details the right way would have been to remove the roof tiles from the outside due to there being no felt. You could have then worked from the outside, dropped in the celotex against the old plaster board and between the rafters (no dust inside), the fitted breathable membrane over the top, tlx gold, cross batten and put the tiles back on.

You might have needed to cover with a scaffold cover as you are doing part time but that's what properly is.

I know....I'm doing exactly this at the moment....roof is filly open.

 

[cjard]

Either that, or call the Icynene guys to come and spray it on in liquid form and let it set. Not quite as good a U value as celotex but the airtightness of the fit will make up for it

I've worked with several different brands on my conversion and they're all slightly different - some the dust is way more irritating than others.

I bought a table saw and fitted it out with a 14 inch blade. It can get most the way through a 140mm board and I just snap the rest, the burred edge helping to retain the board in the wall/ceiling. The fence helps make cuts so straight I only leave myself a 3 mm tolerance when fitting it and as another poster said, the biggest problem is getting a face full of dust when you push the PIR board into the timber frame cassette and all the air rushes out and blows crap in your face. Liberal use of expanding foam was another good point - I genuinely would just cut the board at a rough angle or 362mm and then foam the rest of the gap up. Everbuild do a foam gun that has a long bendy nozzle (ebay for bendy foam gun) that helps with overhead install but be aware that unlike a normal gun the valve is at the handle end not the nozzle end so it drips foam constantly and needs more care and attention to cleaning to avoid blocking the tube with cured foam.

For some awkward install locations it might be worth investing in a "touch n foam" spray pak, that sprays urethane foam from a couple of "gas bottle" sized canisters - plenty youtube videos on that one

You can get dedicated PIR saws that massively reduce the dust generated when cutting - example a bahco profcut.. does work, is like a big breadknife, but beware that cutting thicker boards (>100mm ) is very hard without an assistant to help spread the gap as the saw doesn't really have a set so it gets trapped by the material squeezing together

As Dutch points out, sometimes taking stuff apart can give a faster, easier, better job.. What about battening out the underside of your roof, use a flexible insulation between the wibbly rafters and then rigid board between your new perfectly spaced battens? Is losing head height an issue?

 

[Scoob72]

Cut Celotex with the sharpened edge of a wallpaper stripping knife. Nice straight cuts, zero dust.

 

[noseall]

Cut Celotex with the sharpened edge of a wallpaper stripping knife. Nice straight cuts, zero dust.

You have obviously not had to do much fitting have you.

 

[Chri5]

I use a trusty bread knife to cut with, minimal dust and as accurate as you need.