# Forum Home Renovation Plastering  Outdoor Deck Ceiling - what type of plasterboard?

## chrisbirmele

I want to add a ceiling to my outdoor deck using plasterboard.  The deck is covered with a ColourBond steel roof. 
Despite being an outdoor deck, I am contemplating using standard plasterboard - because of the weight.  A square meter weighs approx. 4kg and I have 20m2 to cover, so this would add about 80kg of weight to my roof. 
The (probably) more appropriate water resistant types of plasterboard weigh twice that, so it would add 160kg to my roof.... 
I am sure the roof structure could handle it but I am not comfortable with adding this sort of weight, considering the roof is 100% watertight AND I plan to paint the plasterboard ceiling with an outdor paint anyway.... 
Any thoughts on this?   Thanks!

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## masterplasterer

Standard plasterboard will sag, especially if the deck gets wet. I have seen ceiling plasterboard sag on 450mm centres outside. Fibro could be an option if weight allows.

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## Gaza

we use 6mm recessed edge villaboard, set with james hardie external base & top coat. 
not sure about the kg/m2 but it does not seem that much differnet than 10mm plasterboard

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## chrisbirmele

> we use 6mm recessed edge villaboard, set with james hardie external base & top coat. 
> not sure about the kg/m2 but it does not seem that much differnet than 10mm plasterboard

  Hi,  6mm Villaboard weighs about 7.8kg /m2 so its similar to the water resitant plasterboard which I try to avoid.  Rgds.

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## Gaza

> Hi, 6mm Villaboard weighs about 7.8kg /m2 so its similar to the water resitant plasterboard which I try to avoid. Rgds.

  yea  
but after the normal 10mm plasterboard sucks in the water it would weight 25kg/m2

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## masterplasterer

> but after the normal 10mm plasterboard sucks in the water it would weight 25kg/m2

   :Biggrin: lol! Very funny. :Biggrin:  Paper and chalk, is not the answer .

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## manofaus

perhaps coreflute plastic sheeting? The stuff they make real estate signs out of. Stick it up with liquid nails. The joints are a bit of a bugger but if you cut it nicely you can inlay one inside the other. Dunno about paint sticking to it. I used it in a small shed.

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## chrisbirmele

well, not sure if you read my original message at all.  the ceiling is for a colourbond covered roof, so not sure how the plasterboard is suppose to get wet. 
Still waiting for more constructive feedback....

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## Gaza

> outdoor deck

  plasterboard goes inside!!! 
cement sheet / villaboard goes out side!!

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## masterplasterer

Hi Chris 
It doesn,t need to get wet, it will absorb the moisture out of the air. If the ground gets wet below, it will draw condensation. What sort of structure is it? How far will the plasterboard need to span? 
mp

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## chrisbirmele

The deck are is about 3.6m by 5m.  The roof is supported by timber beams approx. 15cm by 6cm, 45cm apart. 
I now am looking around for some lightweight cladding instead of plasterboard (have been convoinced its the wrong material  :Redface: )) so if you happen to have any suggestions ....(I hate the look of cement sheets) 
Thanks

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## Ronaldo451

MDF Sheets, ply?

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## kevin pickering

hi chris - is there any companies over there that stock to 10mm hollow soffit board ? they come in 300mm wide x 5mtr long tongue and groove sheets . perfect for outdoor ceilings as they do not get affected by moisture / rain . 
i would add a picture of the product we stock if i only knew how to bloody download one  :Annoyed:     . infact try my website it may help  :Doh:  www.innovatedsolutions.com.au  
good luck. :2thumbsup:

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## chrisbirmele

looks good ....  any plans to open a branch in Sydney anytime soon ?    :Redface: )

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## kevin pickering

no chris , not yet a while anyway , the single depot here in perth is more than enough to handle at present.  
shame really , i feel these products are a lot more suitable for the east coast climate as well .  
anyone fancy a franchise ??????  :Sneaktongue:

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## PlasterPro

<TABLE style="BORDER-TOP-WIDTH: 0px" class=tborder border=0 cellSpacing=1 cellPadding=6 width="100%" align=center><TBODY><TR title="Post 765994" vAlign=top><TD class=alt2 width=125 align=middle>chrisbirmele</TD><TD class=alt1>The deck are is about 3.6m by 5m. The roof is supported by timber beams approx. 15cm by 6cm, 45cm apart. 
I now am looking around for some lightweight cladding instead of plasterboard (have been convoinced its the wrong material  :Redface: )) so if you happen to have any suggestions ....(I hate the look of cement sheets)</TD></TR></TBODY></TABLE> 
So if you want to use  villa board just get it stopped up as you would a indoor ceiling and it looks micky mouse and its water proof,  :Biggrin:

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## Buggermedumplings

If the roof is watertight, normal plasterboard wil be fine.  Don't think you need to go to the expense of blueboard/villaboard and as long as its hung/backblocked/stopped up right it will last for years.  I completed our outdoor area in standard plasterboard (6x8m) and no issues with moisure, sagging or cracks years later.  Your bathroom ceiling is bound to cop more abuse than it would.

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## masterplasterer

I couldn't recommend standard plasterboard outside to my mother in-law, God bless her. You guys must be getting a better quality board in Melbourne.

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## Buggermedumplings

> I couldn't recommend standard plasterboard outside to my mother in-law, God bless her. You guys must be getting a better quality board in Melbourne.

  Why though?  Almost all bathroom ceilings are standard board and it would cop more punishment from steam compared to a watertight, outdoor deck area?

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## Gaza

what about when the rain comes in under the roof, every home i have seen has cement sheet eves not plasterboard.

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## masterplasterer

A lot of problems occur through the back of the plasterboard (unsealed). An outdoor ceiling is subject to long periods of high relative humidity, and varying ambient temperatures. The opposite is true in a (normal) bathroom. This can lead to condensation forming on the substrates above. Unless measures have been taken to eliminate condensation ie. moisture barriers, insulation, adequate cross ventilation, no guarantee can be given. While there are  exceptions, I have repaired too many plasterboard ceilings to confidently recommend it's use externally.

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## Rod Dyson

I agree with master plasterer.  No way would I put plasterboard externally.  Plasterboard will soak up humidity and moisture in the air.   
I always look at thing from a risk to reward ratio.  Sure you will get situations where plasterboard will be ok for years, this could be due to many reasons.  Yet you will get some horror results other times.   Why take the risk. 
Really the only alternative for a flush finish is villaboard.  Or else go for timber, there are not too many cost effective options. Luxalon aluminum ceilings are light but expensive. Lightweight options are generally going to cost more unless you go for a crappy finish. 
Cheers Rod

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