Browse Forums Building A New House 1 Sep 21, 2015 11:38 pm Hi there, Does anyone know if you can use normal plasterboard (not fire proof or water proof) for external ceiling under alfresco and porch? Our builder says they only use normal plaster and if we want them to use anything else it will cost extra. Apparently the area is too big to use fibre cement sheeting, at least that's what they told me. We are also in BAL 12.5 bush fire area and have already added BAL 12.5 bushfire requirement in our quote which include a heap of extras such as sarking to roof etc... but it doesn't mention anything about the plaster board ceiling. Doesn't it have to be at least water proof for outside use? Wouldn't you get mould otherwise? Sounds strange to me... Re: Plasterboard for alfresco and porch ceiling? 2Sep 22, 2015 5:33 am Standard plasterboard is fine. You just need to use a non-combustible material for your porch/alfresco ceilings. Of which standard plasterboard is. Our house/land is bal29 rated and we went through it all with our builder. They were trying to hit us with an upgrade to villaboard, but couldn't explain why, or how standard plasterboard wasn't acceptable. They ended up backing off as soon as I sent them an email from a plasterboard supplier which confirmed my thoughts. Re: Plasterboard for alfresco and porch ceiling? 3Sep 22, 2015 9:42 am Hmm, ok... A friend told me they had their alfresco ceiling done in normal plasterboard and it's gone mouldy... On gyprock's website it says "for internal use"... There are fire and waterproof plaster so why wouldn't you use that? Re: Plasterboard for alfresco and porch ceiling? 4Sep 22, 2015 10:53 am The codes stipulates 6mm hardiflex or equivalent Standard plasterboard is not the equivalent, though it is non combustible, under prolong temperature exposure over time it fails. Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Plasterboard for alfresco and porch ceiling? 5Sep 22, 2015 5:50 pm StructuralBIMGuy The codes stipulates 6mm hardiflex or equivalent Standard plasterboard is not the equivalent, though it is non combustible, under prolong temperature exposure over time it fails. Hi StructuralBIMGuy, where is the reference in the 2015 NCC re this? I asked my builder and he says he was doing cement sheet for front porch ceiling but plasterboard for the alfresco? Thanks. I have the 2015 NCC's but can't find referrence. Re: Plasterboard for alfresco and porch ceiling? 6Sep 22, 2015 7:49 pm Plasterboard manufactures on line installation guides say that external plasterboard is subject to higher wind pressures that when installed internally. Depending on your site specific terrain category this means that either the batten spacing must be closer together or thicker sheets must be used. In addition the sheets need to be screw fixed not adhesive fixed. Re: Plasterboard for alfresco and porch ceiling? 7Sep 22, 2015 8:29 pm It also depends on the fire attack direction etc,...so the plasterboard alfresco could be on the the opposite side? BAL 12.5-> AS3959 Sect 5.4c Cladding... Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Plasterboard for alfresco and porch ceiling? 9Sep 22, 2015 9:20 pm Beetaloo Plasterboard manufactures on line installation guides say that external plasterboard is subject to higher wind pressures that when installed internally. Depending on your site specific terrain category this means that either the batten spacing must be closer together or thicker sheets must be used. In addition the sheets need to be screw fixed not adhesive fixed. The codes are not that specific but it helps to understand the underlying physics... AFAIK, no-one has done bush-fire computer simulations using Multiphysics software. With cloud computing power I would think they aren't that far away. Here is one I've done on Storm wind load assessments https://plus.google.com/u/0/114544938995916531570/posts to which I might need to add Thermal, chemical, combustion and degradation equations... (LOL, I'd be killed if I went back to study again ) Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Plasterboard for alfresco and porch ceiling? 10Sep 23, 2015 3:40 pm From reading the Australian Standard associated with this, the ceiling materials is not specified, just wall materials up to 400mm above floor height. I can't see ceilings being included in this. Re: Plasterboard for alfresco and porch ceiling? 11Sep 23, 2015 7:32 pm It's a little vague (code) regarding ceilings but my understanding is Cladding for Walls, Eaves linings and gables should comply with 5.4 Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Plasterboard for alfresco and porch ceiling? 12Sep 23, 2015 8:48 pm StructuralBIMGuy It's a little vague (code) regarding ceilings but my understanding is Cladding for Walls, Eaves linings and gables should comply with 5.4 Well reading AS it nominates the 400mm level as up to where the minimum 6mm cement sheet or equivalent is required. I am thinking that is a height that may have ember attack accumulating and embers would not sustain attack higher or on the ceiling. There is nothing in AS that I found was clear about ceiling materials so it may be up to builder interpretation. My builder tells me he is using plasterboard but I have asked for minimum Gyprock Aquachek due to moisture exposure but as yet he has not replied. I will probably just get what my Volume builder gives me by looks of things. I am not doing one of their $1,000 variations for it that is for sure. Thank you alexp79 and gommeqld for your advice, that's very helpful, thanks 3 8052 What we have done in a few theatres ( including my own) is run 2 layers of 13mm gyprock, but sounds insulation especially for the bass is really tricky as a lot of that… 4 2613 Plasterboard Gyprock is very popular as a reveal liner these days. You need to provide a way of supporting it, we use a modified timber reveal or bracket. You will be… 1 4766 |