It is currently 28 Mar 2024, 16:56

Big washers for screwing up celotex

This forum is for any general questions, queries or plain old chinwaggery on Woody stuff in general.

Big washers for screwing up celotex

Postby the bear » 27 Nov 2017, 18:10

I'm currently renovating my house. There are small bits I'm doing myself, though not as much as I'd like to and nothing on Mikes scale.

I need to screw some 60mm celotex externally to a timber gable. I need some plastic washers for the screws, is there something specific I should be getting? And is there a rule of thumb for the diameter of the washer for a given thickness of celotex? On this occasion its 60mm.

Cheers

Mark
the bear
Sapling
 
Posts: 448
Joined: 21 Jul 2014, 21:50
Location: Surrey
Name:

Re: Big washers for screwing up celotex

Postby Mike G » 27 Nov 2017, 18:15

What is going on the over the celotex?
User avatar
Mike G
Sequoia
 
Posts: 9833
Joined: 30 Jul 2014, 22:36
Location: Suffolk
Name:

Re: Big washers for screwing up celotex

Postby the bear » 27 Nov 2017, 18:38

On one gable breather membrane, counter batterns, batterns and tile hanging.
On another breather membrane, batterns, render board, render (with oak boards to make rendered panels)

mark
the bear
Sapling
 
Posts: 448
Joined: 21 Jul 2014, 21:50
Location: Surrey
Name:

Re: Big washers for screwing up celotex

Postby Mike G » 27 Nov 2017, 18:51

I hope you've got a vapour barrier on the inside, as the Celotex is a bit of a vapour barrier itself but in the wrong part of the wall.

Anyway, to your question. If you are counterbattening, then this will hold the Celotex very firmly indeed. All you need is something temporary to hold it in place before you batten out. A few nails per board, some wedges, off-cuts of DPC to act as a washer for 2 or 3 screws.....anything which just holds it ready for battening. Then you'll fix your battens through the Celotex into the wall behind (don't forget to mark stud locations if it's a timber frame).
User avatar
Mike G
Sequoia
 
Posts: 9833
Joined: 30 Jul 2014, 22:36
Location: Suffolk
Name:

Re: Big washers for screwing up celotex

Postby the bear » 27 Nov 2017, 19:02

Mike
its an oak frame, the oak framing company have specified the wall build up. They have specified duplex plasterboard, which I believe contains the vapour barrier?
Mark
the bear
Sapling
 
Posts: 448
Joined: 21 Jul 2014, 21:50
Location: Surrey
Name:

Re: Big washers for screwing up celotex

Postby Mike G » 27 Nov 2017, 19:38

Yes it does. Presuming that they are going to be plastering between rather than over the frame internally, I personally wouldn't have put Celotex outside the frame. However, that's their call.
User avatar
Mike G
Sequoia
 
Posts: 9833
Joined: 30 Jul 2014, 22:36
Location: Suffolk
Name:

Re: Big washers for screwing up celotex

Postby the bear » 27 Nov 2017, 19:58

Mike

Slight tangent leading on from what we have discussed already. I live in what essentially is a chalet bungalow. The upstairs rooms wholly in the roof . None of these "old" roofs/rooms have a vapour barrier. Standard plasterboard internally as far as I can tell, 50mm celotex between 100mm rafters, Roof membrane (no idea whether breathable or not but probably not given age) battens, tiles. I realise regs change over time. Is this roof not as good, is it at risk of something going wrong, does it work because of other reasons?

Mark
the bear
Sapling
 
Posts: 448
Joined: 21 Jul 2014, 21:50
Location: Surrey
Name:

Re: Big washers for screwing up celotex

Postby Mike G » 27 Nov 2017, 20:10

That should be OK if it has eaves ventilation. Ideally it would have foil backed plasterboard, but with eaves vents and hopefully ridge vents that should be fine. If you ever decide you need more insulation upstairs, then pull out a small bit of plasterboard and see if it has foil. You can overboard your plasterboard with Celotex and then plasterboard, but that should be foil backed.......absolutely essential if your existing p/b has foil.

-

Are you OK with what I suggested about holding the Celotex temporarily, then using the battens to hold it permanently?
User avatar
Mike G
Sequoia
 
Posts: 9833
Joined: 30 Jul 2014, 22:36
Location: Suffolk
Name:

Re: Big washers for screwing up celotex

Postby the bear » 27 Nov 2017, 20:40

Ref holding the celotex - yes understand the battens will hold it ultimately. Just might be temporary for longer than normal as i fit that bit in around my day job until the roofers do the battens. Thank you.

Mark
the bear
Sapling
 
Posts: 448
Joined: 21 Jul 2014, 21:50
Location: Surrey
Name:


Return to General Woodworking

Who is online

Users browsing this forum: No registered users and 12 guests