Vapour barrier?

[RF Lighting]

Hello all.

I am hopefully going to be doing a job in the local scout and guide hut shortly.

It involves the complete refurbishment of the toilets area in the building.

Two of the walls are external walls, and are constructed of 4" x 2" timber.

It is clad on the outside with what appears to be creosoted hardwood tounged and grooved boards.

The inside will be 12.5mm plasterboard with skimmed finish, and the bottom half of the wall will be tiled onto this.

I will be removing all the internal wall covering, which presently is a combination of plasterboard and hardboard.

In the wall there is about 1" of fibreglass, and what I would describe as tar paper between the external cladding, and the external face of the wall framework.

I'm going to be filling the wall with 100mm of rockwool as part of the project.

Now the question (finally )

Once the wall is bare and insulated, should I cover it with a vapour barrier before I plasterboard?

I have seen some information on here about it, and seen it used in some properties, but I'm not sure.

Sorry for rattling on

 

[Deluks]

Absolutely, although you can do it in one go by using vapour check (foil backed) plasterboard

 

[RF Lighting]

Thanks for your reply

That looks far too expensive for a Yorkshire man

Am I right in thinking I would only do the two external walls?

The other two are internal. One to a store room, and one to the main meeting hall.

What about the ceiling? There is a small loft above the toilets, with a felted pitched roof above.

 

[Deluks]

Yes, external walls only. and the ceiling.
What it will do is to prevent vapour (ie: steam from taps and wee, breath, sweaty scouts who have just come in after some strenuous bouts of gin-gang goolie, etc), from passing through the walls and turning into water (condensation) once it hits the cold side of the insulation, or the cold surface of the roofing felt.

The moisture can freely pass through internal walls, as one would expect the temps to remain similar throughout the building, thus keeping the 'steam' above the temperature at which it would condensate.
Of course background ventilation and probably a small extractor fan in the toilets would be wise. (otherwise the mould would appear on the walls overnight when the heating's off, if the air remains moist)


Absolute worst case scenario of not using VB would be damp/mould within the walls, and moisture within the roof space causing the joists to rot.

Do it this way and Akela is sure to give you your 'drylining' badge!

You might wanna suggest upping the pb to 15mm or even gyproc plank (19mm!) Less likelyhood of teenagers sticking their head/foot/woggle through the wall. Because they will try to.

 

[RF Lighting]

Thanks for that

The plan is to put a 4" extractor into the toilets anyway, so it sounds like all will be well

I'll have a look into the thicker plasterboard too.

If I get the job, I'll stick up loads of pics in the your projects forum