DIY Doctor

Exposing ceiling joist and spraying with foam insulation

Postby Redrooster » Tue Dec 22, 2020 4:25 pm

Looking at exposing the ceiling joists in a first floor bedroom with loft space above.

The loft is due to be spray foam insulated on the underside of the pitched roof but want to know what I should be doing to avoid moisture build up and ensure the bedroom stays well insulated.

Currently the room has artex and plasterboard ceiling tacked on to the joists. I would like to remove this and then replace the ceiling but above the joists to expose them in the room.

What insulation should I install to avoid moisture and heat loss?

I was thinking along the lines of putting a 5mm timber cladding above the joists then insulating above that.

My questions are (and growing as I research this)

Do I need a moisture control membrane above the timber cladding?
Should I plasterboard above the cladding?
Do the joists need treating as they will be exposed?

Any help on this would be very much appreciated as I am going round in circles and don't want to create a problem with moisture etc at a later date.

Thanks in advance
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Simply Build It

Postby stoneyboy » Wed Dec 23, 2020 10:00 pm

Hi redrooster
Artex ceilings are notorious for containing asbestos so suggest you get a sample checked before you start work.
spraying of the underside of the tiles should include the provision of cross ventilation in line with building regulations to stop condensation. If there is cross ventilation you can top the room with normal fibre insulation. Your exposed joists will probably be a mess so will need painting,
Regards S
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