Loft insulation dilemma

[Joey]

Last dozen or so I did I cut with my big Makita circular saw , connected up to a big old Titan hoover , with a good dust hood on and a huge fan blowing the residual dust across the fields ...

Cutting the first 90mm with the Mak and then the last 30mm by hand worked really well , lovely and square and the handcut edge made the fit really snug.

But having 'eaten' the equivalent of a few dozen sheets over the years I flatly refuse to have anything to do with it these days ...

I let the young clever buggers who know everything struggle with it , and suffer the wrath of the BCIs when the shoddy fit is condemned ...

Im getting our gaffa to go halves with me on a Festool insulation saw. I already have the dust extractor so the job should be pretty clean.

That'll get the bulk of it done, then I only have to worry about cuts around the hips and valleys etc.

 

[Stan79]

Just one point , if you're planning to use Celotex or equivalent between the rafters I'd recommend waiting until you convert the loft.

It's a sh*tty job at the best of times ( one I've done umpteen times over the years but flatly refuse to entertain these days ) but the very thought of cutting sheets to fit after roughly cutting them outside and then passing it all up through a loft hatch into an enclosed unventilated roofspace gives me the heebie-jeebies ...

I’ve got a bit of time off work coming up later in the year so will just take it steady but I totally agree it’s a crap job. Particularly on an older house where stuff isn’t square!

 

[Woodbutcher]

Im getting our gaffa to go halves with me on a Festool insulation saw. I already have the dust extractor so the job should be pretty clean.

That'll get the bulk of it done, then I only have to worry about cuts around the hips and valleys etc.

I'd recommend trying one first on some 150mm before you splash out on one , the guy I was working with got one for a similar job we were doing when they first appearred , he's a Fusstool tart so it didn't surprise me when he unpacked it ...

Quite frankly it was sh*te , the cut was very much like the one you see when someone tries cutting in a letterplate in a solid Oak door with a blunt jigsaw ...

That's when I started using the circular saw ...

 

[shergar]

Doing a one off roof in an older house, don't even use a hand saw. Slice your Celotex with a large butchers knife.

 

[Woodbutcher]

Doing a one off roof in an older house, don't even use a hand saw. Slice your Celotex with a large butchers knife.

Must be some knife and some arm to 'slice' the 150mm stuff ...

A doddle on anything up to 50mm I agree though.

 

[Richatdmu]

If you do decide to go with PIR insulation, I could recommend seconds and co. They sell seconds quality celotex and kingspan you have to buy over a certain amount, but there was not much difference between what they delivered and the stuff the local builders merchant delivered.

 

[Woodbutcher]

If you do decide to go with PIR insulation, I could recommend seconds and co. They sell seconds quality celotex and kingspan you have to buy over a certain amount, but there was not much difference between what they delivered and the stuff the local builders merchant delivered.

I've seen first hand some shocking stuff supplied by them , especially the beginning and end of run sheets where the thickness is nowhere near spec and dreadfully uneven.

They used to filter the really bad stuff out and supplied mainly physically damaged sheets i.e. broken corners and bad forklift damage but now they just bung everything on a load and cover themselves with a "what did you expect" attitude.

Personally I'd rather use 1st quality material and have no risk of comebacks later down the road , they're fine for large DIY projects but for professionals I couldn't personally recommend them any more.

 

[william bonny]

Reading this thread makes me want to live in a log cabin in the woods even more

 

[Woodbutcher]

Reading this thread makes me want to live in a log cabin in the woods even more

I'd build you a cabin , but you'll have to get someone else to insulate it , unless you use sheep's wool ...

 

[william bonny]

I'd build you a cabin , but you'll have to get someone else to insulate it , unless you use sheep's wool ...

Thanks for the offer, mucho appreciated .... but as I'm a joiner/carpenter I feel I really should do the job myself ... although it took me 2.5 years to build the house I'm in at the minute
Imagine it though... hopping off the treadmill of life and building a small cabin on a patch of the English countryside and living in peace & harmony with the dog (the missus could bugger off back to her place) I can dream the dream

 

[Fbrit]

Quickest and easiest way to rid the artex is to over board the ceiling don’t touch it. Tape and joint then decorate done in a day
As for insulation 270mm of insulation is the current minimum thickness to comply with document L
Loft conversion will require new joists installing as the current ones will not be supportive.

^^^this^^^
Additionally, are you aware that artex contains asbestos, with is why they stopped using it in construction. Either skim plaster over it or as above over board it and seal it in.

 

[Woodbutcher]

Thanks for the offer, mucho appreciated .... but as I'm a joiner/carpenter I feel I really should do the job myself ... although it took me 2.5 years to build the house I'm in at the minute
Imagine it though... hopping off the treadmill of life and building a small cabin on a patch of the English countryside and living in peace & harmony with the dog (the missus could bugger off back to her place) I can dream the dream

Well I've pretty much hopped off the treadmill and live in the little thatched cottage set in an acre of Suffolk that I first arrived at as a three day old , so no imagination needed ...

And after a rethink you can build your own cabin , I can't be arsed , too many squirrels need shooting here to get me back on the tools for someone elses house ...

 

[Woodbutcher]

^^^this^^^
Additionally, are you aware that artex contains asbestos, with is why they stopped using it in construction. Either skim plaster over it or as above over board it and seal it in.

You're like a cow's tail fella , All behind ...

 

[william bonny]

Well I've pretty much hopped off the treadmill and live in the little thatched cottage set in an acre of Suffolk that I first arrived at as a three day old , so no imagination needed ...

And after a rethink you can build your own cabin , I can't be arsed , too many squirrels need shooting here to get me back on the tools for someone elses house ...

Sounds like you have found your own heaven already, in fact, you have always been there, that's just awesome.
Suffolk is such a nice county, almost as nice as Norfolk . My best ratting perm is in Suffolk, for obvious reasons I can't say much more.
Live the dream my friend and shoot plenty of squirrels

 

[Woodbutcher]

Suffolk is such a nice county, almost as nice as Norfolk

There's a dead simple way to distinguish between the two ... you just put the term 'n Good after each one ...

 

[Stan79]

I'd recommend trying one first on some 150mm before you splash out on one , the guy I was working with got one for a similar job we were doing when they first appearred , he's a Fusstool tart so it didn't surprise me when he unpacked it ...

Quite frankly it was sh*te , the cut was very much like the one you see when someone tries cutting in a letterplate in a solid Oak door with a blunt jigsaw ...

That's when I started using the circular saw ...

Was he using it freehand or on rails?

 

[Deguello]

Did the PIR and foil meet building control regs? How thick was the PIR (roughly if you can’t remember precisely.)

It was 50mm Celotex and our Building Control Freak (officer) was happy, for once, the foil was possibly overkill.
He was more concerned with the airflow.

This house is over 100 years old and when I gutted the roof space I noticed the 4 purlins were all different sizes and had various cuts holes and notches, clearly recycled timber.
It would be nice to think they were once ships timbers as we have an old boatyard about a mile away, but more likely just from an older house or barn.
The rear of the roof, which is north facing and doesn't bear the brunt of the weather didn't have a membrane fitted, and was in its original condition, torched with lime mortar.

 

[Ianbarnstaple]

When insulating a roof I’d go for stuff with a high thermal mass. That way it takes all day to heat up in summer and starts radiating back out as soon as the sun goes down. I’ve just built a house and the upstairs loft rooms have 300mm rockwool batts between them, then a 40mm gap then celotex backed board (only 22mm or so). I’m so glad I got the foam backed boards as every little helps. Was lovely and warm in winter but in Devon the summer sun can be grim in a loft.

 

[shergar]

When insulating a roof I’d go for stuff with a high thermal mass. That way it takes all day to heat up in summer and starts radiating back out as soon as the sun goes down. I’ve just built a house and the upstairs loft rooms have 300mm rockwool batts between them, then a 40mm gap then celotex backed board (only 22mm or so). I’m so glad I got the foam backed boards as every little helps. Was lovely and warm in winter but in Devon the summer sun can be grim in a loft.

High thermal mass can be used to advantage. Where possible I'll locate radiators against internal masonry.
For new houses rads go under window to allow greatest option for internal layout but effect is to lose more heat through external wall.

 

[Dudd I]

Im getting our gaffa to go halves with me on a Festool insulation saw. I already have the dust extractor so the job should be pretty clean.

That'll get the bulk of it done, then I only have to worry about cuts around the hips and valleys etc.

Bosch do, or did, an insulation cutting blade for jigsaws. Still use the festool extractor with it