Plasterboard Thiknesses

[Cyberdog]

Hi, What is the correct thickness of plasterboard for ceilings and walls. Thanks.

[Andrew Gabriel]

Usually 9mm on ceilings, 12mm on walls (subject to more knocks). If the ceiling needs to provide 30 minutes fire protection, you'll need thicker. Thicker on walls can help with sound reduction too.

[Cyberdog]

[.]

use 12.5mmfor ceilings. add a layer of 9mm for better soundproofing.

[Weatherlawyer]

If it were my house and I had kids and money no object, I'd have it thick as posible in downstairs rooms. Loft ceilings are just a matter of heat proofing but downstairs is a risk for life and limb.

I'd insulate it too preferaby with rockwool in bags above it. You just feed the mattresses up as you go. They are sheets of glass or rock wool in binbag like pillows. But just poking strips of wool up there as you go or pinning it up in string, will work fine.

Put a layer of pink faced stuff up at least but a thinner barrier of ordinary stuff would inhibit smoke if you want two layers. The pink faced stuff is thick and has a layer of glass in it to hold it up a little longer while your treasures make their escape in a fire.

What you do with 2 layers of plasterboard is cover the joints in the first layer with the full face of the next. So no smake can seep past. Don't go daft with the first layer's screws.

Remember you want longer screws with the thicker layers. And where the joists are. (Mark the walls with a scrap of board for a chalk.)

Then take it all down again to put your wires in.

[meow2222]

use what you want, but I would, like Weatherlawyer, err more towards 1" where it fits, assuming finances arent desperate. Its much better. 9mm otoh has all the robustness, sound deadening and fire resistance of a cardboard box.

NT

[Cyberdog]

I have just realised something I should have mentioned. The plasterboard for the ceilings is going straight over the old lath and plaster ceilings, and the plasterboard for the walls is going to be used via dot and dab onto breeze blocks. If that makes much difference. Thanks

[The Natural Philosopher]

Cost difference between all plasterboards is not so great that you should worry.

Use 12mm throughout is my advice, if its over existing stuff.

[Weatherlawyer]

Don't you just love it when they tell you all about the job after you have given extensive and painstaking advice?

Cyber, you absolute cretin. Do you really think you are up to this sort of thing?

How are you going to find out where your ceiling joists are?

You might be best putting roof batons up at 400 centres, running across the joists (which will be at imperial centres)

This will give you a chance to get the ceiling flat -maybe even level. Put a baton across both ends and one in the centre, then run a line along them and make sure that you will be able to get all the other batons in there.

If not, pack out the baton that is at the highest end of the room if it is out of level. I wouldn't worry too much about bring it all on the bubble. It's just that if it is quite a bit out you could make the most of the chance to fix it.

Use 3" 10's. Make a load of packers or wedges if you have a chop saw, before you start. Cereal boxes make good packing. Corrugated cardboard doesn't.

The more packing you decide to use the more of a job it's going to be. You can get away with thin plaster board at least.

1 1/2 days to baton 1/2 a day to board. Get cracking.

If it falls on your head, give us a shout.

[Owain]

And if you buy lots of it and get qty disc it may be cheaper than a mix of thinner stuff.

Owain

[Chris Bacon]

[ snip ]

What's a "baton", I thought it was something used by a conductor (music, not 'bus), someone in a relay race (etc.).

What d'you mean by a "roof baton"? A bit of 2x2, or what?

Sometimes joists are not equally spaced.

To fix battens will require finding the joists anyway, so (unless the joist is "S" shaped (unlikely) overboarding is just as easy.

3 by 10s? Through what, exactly?

My goodness. I thought you were an irascible builder, not an irascible DIY bodger!

That's two days. He'll be able to get in lots of visits to the pub., sleep, and all sorts as well as "doing his ceiling".

Look out Foxy Loxy.

[meow2222]

oh yes. My suggestion of 1" is not pertinent to the OPs situation. Maybe OP will think a lil more next time.

NT

[Cyberdog]

One more question. I have a Skimming trowel which is about 8"-10" long. I have also seen longer plastering trowels. Are these all for skimming or are some for putting the bonding coat on with. Thanks

[Andrew Gabriel]

Same tool is used for bonding and skimming (and rendering). Size is whatever the user prefers, but I would say 8-10" is much too short -- mine's 14". A short one can be handy in tight spaces.

[Chris Bacon]

Gosh.

[Cyberdog]

Does a longer one give a better finish than a short one???

[Andrew Gabriel]

A longer one is going to cover more area faster, both with the initial coverage and smoothing down and polishing, and that might enable you to do a better job. Are you sure yours is really a plastering trowel, and not intended as an adhesive spreader or some such?

[Mark]

Plastering trowels are normally 11 or 14 inch but you can get bigger, unless you have strong wrists or are used to manual work the smaller size is good to start with.

-

[The Natural Philosopher]

That is a question for your partner, not this NG.

[meow2222]

I'm told all sizes above 4" feel and perform the same. But I wouldnt know, I've only ever used one.

NT