plasterboarding loft space

[masona]

So it looks like I'm alright then as I have foil backed plasterboard in the new part of the building.

Too much to write as I can only type 4 words per mins so have a read here from Insulation and Condensation by Matthew Marks 17/5/99.
I now started to put 3"x1" timber flat onto roof rafter so the plasterboards have a cross air-flow just behind the plasterboards as well as the 50mm air-flow at the back plus insulation, maybe a bit over the top but more the merrier.

 

[mildmanneredjanitor]

With all these additional rafters, 6" joists, insulation etc. I reckon you've only got a crawl space left!

 

[oilman]

Thanks masona, I'm beginning to feel more comfortable. Since I've got foil backed board, I dont think there will be too much trouble even though the insulation fills the gaps. I'll drill an inspection hole to check for condensation.

Vinyl wall paper on the ceiling would provide a vapour barrier.

 

[masona]

With all these additional rafters, 6" joists, insulation etc. I reckon you've only got a crawl space left!

I'm getting smaller every year or is it my kids getting taller ?

 

[legs-akimbo]

You have two alternatives to insulating between rafters you either leave a 50mm air gap over your insulation and vent it to the outside or you don't and then you must use some sort of vapour barrier between the room and the insulation to prevent moist air entering the space some local authorities will allow foil backed plasterboard some insist on a plastic membrane

So it looks like I'm alright then as I have foil backed plasterboard in the new part of the building. And the old part has resident gales. From this it appears It's an automatic panic response, or have I missed something?

I think we are all talking at cross purposes with you oilman.. I think while the rest of us are debating the pros and cons of insulating a loft spaces in general terms, you are considering your own personal and individual problem... or have I missed something?

 

[wickerman]

if the air in the attic room was that moist that it would cause problems in the roof Oilman, i think the plasterboards would go first, not only that but you wopuld have black mould growing every where

There is a tile which goes through the felt to vent the roof space and you can buy an extension piece which will go into the attic room and vent that to the outside if there was a problem

But Leg's is correct you have to have a through space between the rafters so air can travel from the soffit up to the rideboard and be vented out there.

 

[-dj-]

I prefer to use 6' x 3' sheet which is easy to handle if you're working on your own. I would go for 9mm plasterboard and use plasterboard screws instead of nails to prevent knocking or breaking the roof tiles.

you should be using 12.5 mm boards for ceilings.
dj.

 

[legs-akimbo]

Agreed!

 

[-dj-]

hello robbo, how you doin, nice to hear a freindly voice. i only found this place a few days ago.

dj.

 

[oilman]

I think we are all talking at cross purposes with you oilman.. I think while the rest of us are debating the pros and cons of insulating a loft spaces in general terms, you are considering your own personal and individual problem... or have I missed something?

You might be at cross purposes, I posted

I insulated our roof with rockwool between the rafters, up against the felt, 20 years ago. The house (original part) is 120 years old, with a tile and felt roof,The house is 3 floors, with the top floor built into the roof space. I got a council grant to do it, and a guy came round to inspect it with the comment he would be happy to see more jobs like it as most are badly done. We have no heating upstairs, and there is generally loads of ventilation around the place. Euphemistically called draughts. As far as I know there is no problem, and on the new part, the insulation is fitted behind foil backed plaster board. Again as far as I can tell there are no problems.



Is this a case of an automatic panic response to insulation, or does it only present a problem in overheated, underventilated houses?

Which seemed to get a general response that didn't address the point I put, so I persued it until I could see an answer. It's an irritating trait I have, if I don't get an answer, I keep asking. (Sorry can't use smilies, it screws up my posts).

 

[wickerman]

All i can say on that Oilman is that with tiles the wind can blow under them and maybe take condesation away, but with slates it cant, so pehaps this is what has taken away any moisture

 

[masona]

you should be using 12.5 mm boards for ceilings.
dj.

I was thinking on the term how is john59 going to get the 8'x4' 12.5mm plasterboard up in the loft.

john59 is not applying for any planning or building regulation which I don't agree with so 9mm is acceptable on a 400mm roof rafter for the job he want to use it for. The 12.5mm plasterboard is better if you can and one of the reason for 12.5mm is for gang nailed roof trusses that sometime are over 400mm centre for strength.

 

[legs-akimbo]

Hello d.j So you have found another place to keep you up all night mate eh???
A good tip for getting 8x4 into a loft space is to run a score along the back in the centre along its length and fold it in two, do not break the paper on the other side. You can then offer up the board into the loft with much greater ease and when up there open up the board and tack with the slit side to the back the front of corse is intact fully so when secured it is perfect.

Regards

Robbo.

 

[wickerman]

If i had known that you knew a prison inmate called dj Legs i would never have spoken to you, i suppose you know the other inmates Stoday and Charlie aswell ???

 

[masona]

A good tip for getting 8x4 into a loft space is to run a score along the back in the centre along its length and fold it in two, do not break the paper on the other side. You can then offer up the board into the loft with much greater ease and when up there open up the board and tack with the slit side to the back the front of corse is intact fully so when secured it is perfect.

Hmmm, never thought of that Have you tried it on a ceiling Must be a bit awkward, I suppose it can be done if you're careful