Plasterboard a ceiling

[chessp]

I intend to plasterboard my ceiling as currently I have a cathedral ceiling with exposed beams.
The primary reason for me doing this is to improve the insulation where this will be installed between the existing ceiling and the new plasterboard.
Can anybody advise whether I am going to have an issue with condensation or other problems associated with doing it this way and if so what do I need to do to mitigate against this?
Any help is appreciated.

[Barry_White]

Hi Chessp

Do you have tiles or steel on the roof and do you know if there is foil under the roof and what is you current ceiling cladding.

If you have foil under the roof cladding you shouldn't have a problem with condensation.

[rod@plasterbrok]

I would say that if you don't already nor should you in the future.

[chessp]

Barry White,

Many thanks for the help. I can confirm that I have tiled roof. There is obviously some form, of membrane between the tile and existing plasterboard (between the exposed beams) but not quite sure what it is. As the ceilings are approx 5mtrs high it proves somewhat difficult to get there and see. The house was built in the mid 80's so what is the likelihood that foil would have been used then?

Looking back at the original post I may not have been quite clear. My intention (subject to the outcome of responses here) would be to plasterboard over the existing beams to create a flat ceiling. Within the new cavity created I would install batts and to give me the lighting within the room I would be installing mains voltage downlights (halogen) - potentially CFL which burn cooler.
Now that this makes more sense (to me anyway) do you foresee any problems with condensation or would I need to install any specific type of plasterboard?

[Barry_White]

Barry White,

Many thanks for the help. I can confirm that I have tiled roof. There is obviously some form, of membrane between the tile and existing plasterboard (between the exposed beams) but not quite sure what it is. As the ceilings are approx 5mtrs high it proves somewhat difficult to get there and see. The house was built in the mid 80's so what is the likelihood that foil would have been used then?

Looking back at the original post I may not have been quite clear. My intention (subject to the outcome of responses here) would be to plasterboard over the existing beams to create a flat ceiling. Within the new cavity created I would install batts and to give me the lighting within the room I would be installing mains voltage downlights (halogen) - potentially CFL which burn cooler.
Now that this makes more sense (to me anyway) do you foresee any problems with condensation or would I need to install any specific type of plasterboard?

I don't see where there would be a problem from condensation but the true way of installing insulation is really to have a vapour barrier between the insulation and the plaster and they used to make a plaster board with a foil backing for that purpose. I think it would be overkill and I don't think it is still available. rod@plasterbrok could answer that.

I gather that given the height you will be getting a plasterer in to do the job and given the fact you will need to fix ceiling battens on the under side of the exposed rafters.

Given that the house was built in the mid 80's I reckon they would have used foil under the tiles especially with a cathedral ceiling

[Bloss]

Yep as they said - if you not not have condensation now you won't by doing what you propose.

You will just need to batten up across the exposed beams, have a sparky run all your cables after you have battens in place, fill the void with whatever insulation you intend using and screw plasterboard to the battens.

Simple and should be effective for your aims. The CFC downlights are quite effective and can be bought for around $50 for 4 units from Bunnings and other places. These are NOT halogen which are great energy wasters, but compact fluorescent fittings - low voltage does not mean not low energy and halogen at 240v still uses 50W or so relative to a CFC of around 15W (= 75W incandescent).

For ease of installation and cost savings I have 1m of 3-core (1mm) flexible cable and 3-pin plugs fitted to the units and get the sparky to install lighting base plugs at each point.

This means that he can complete his work in one go and you can cut the holes and simply plug in the lights when you are ready - even after painting so you have no hanging light fittings in the way. Also allows for easy access and removal for any later maintenance work.

[Joister]

if your ceiling is a bit wobbly in terms of levels you can use furring channels in place of wood battens - alot easier to find your levels vs packing battens

other posts on the forum have talked furring channels as well - otherwise do a google on it - usually rondo website will come up or else one such as follows

http://www.gyprock.com.au/technical/technical.asp?section=%2Ftechnical%2Ftechbull%2Fgyprock%2F5475BAC5299D4F49B0751E0C88F59BCE%2F6.htm&contenttype=GYPROCK-TECHNICAL-BULLETIN&id=%7B5475BAC5-299D-4F49-B075-1E0C88F59BCE%7D&cookie%5Ftest=1

good luck

Joister