Browse Forums General Discussion 1 Apr 26, 2022 6:57 pm Starting the early stages of our next home design and looking at two levels- two car garage underneath and the rest of the house on the first level. Footprint is about 15m by 25m so the supporting 15mx25m structure acts as a floor for the house to be built on. The aim is to get the whole living areas above the ground by about 3m. Soil is sandy. Questions: (1) pre cast concrete columns and pre cast floor sections appeal conceptually but anyone know how the cost compares to other structures like steel columns/beams/joists ? Both of these system have the advantage of being built off site and then erected quickly on site. (2) is there a forum or two around that deals with these sorts of discussions? (3) anyone care to share their expertise or experience in the pros and cons of a steel sub floor structure versus concrete sub floor structure? Re: Structural design questions to raise house 3m 2Apr 26, 2022 7:37 pm No idea of what you are trying to do? try putting up more info, plans, etc is it a reno, new build, alternate construction method? The better the info , the better the reply + it helps others OT concrete is still the cheapest, fastest, most available, etc build material in the world by far.... Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Structural design questions to raise house 3m 3Apr 26, 2022 8:27 pm The idea is simple - build a new, single level rectangular home but 3m above the ground on a flat vacant lot. The floor area of the home is 15mx25m, a simple rectangle. The whole house must be sound proof, but I suspect this and other details don't matter yet. At the moment I'm only trying to get a feeling for what the sub floor structure could/should be. If such a floor (3m above the ground) costs, say, $200,000 more if built in concrete than it does if it were built in steel then that becomes a significant factor. If such a floor costs, say $100,000 more if pre cast concrete compared to concrete formed and poured on site then that becomes a factor to consider. If pre fabricated (off site) steel sections subsequently erected on site have great advantages over anything in concrete then that becomes a factor to consider. Hence the open questions....... Re: Structural design questions to raise house 3m 4Apr 26, 2022 8:56 pm I think you need to start with what you want, not the price. Not many houses start with such a large suspended concrete slab. What about timber, what about ultrafloor etc? lots of options with different pros and cons Re: Structural design questions to raise house 3m 5Apr 27, 2022 9:06 am I am guessimating +$1000/m2 for cast in situ on to formwork, suspended slab, beams, columns, pad footings then you are covered for flood, fire and noise, etc. ( commercial rates) Start with the drawings, engineering, quants, etc then compare alternates. Precast concrete yards are 2-3 times cast onsite Cheers Chris Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Structural design questions to raise house 3m 6Apr 27, 2022 10:53 am Why don't you just build two storey timer home with garage under? You don't need a slab. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Structural design questions to raise house 3m 7Apr 27, 2022 2:34 pm StructuralBIMGuy I am guessimating +$1000/m2 for cast in situ ..... So for a 15x25m area = 375m2 that gives a cost of $375,000 and precast gives a cost of $750,000 to $1.125M. Surely I misread something? If not then concrete cast on site or pre cast is certainly not an option. building-expert Why don't you just build two storey timer home with garage under? I'm guessing that's a typo and is a "timber" home. Fair question but I'm looking to avoid coastal flooding on this site so I'm assuming (but I could be wrong of course) that a steel or concrete subfloor structure will be more robust. Sound proofing is also a high priority so again I'm wondering if concrete has an advantage over steel and timber for flooring. Re: Structural design questions to raise house 3m 8Apr 27, 2022 3:37 pm gommeqld StructuralBIMGuy I am guessimating +$1000/m2 for cast in situ ..... So for a 15x25m area = 375m2 that gives a cost of $375,000 and precast gives a cost of $750,000 to $1.125M. Surely I misread something? If not then concrete cast on site or pre cast is certainly not an option. building-expert Why don't you just build two storey timer home with garage under? I'm guessing that's a typo and is a "timber" home. Fair question but I'm looking to avoid coastal flooding on this site so I'm assuming (but I could be wrong of course) that a steel or concrete subfloor structure will be more robust. Sound proofing is also a high priority so again I'm wondering if concrete has an advantage over steel and timber for flooring. What is your problem with soundproofing? Soundproof batts and double glazed windows will do the trick. I am right on the beach and sound of the sea is magical, why would you want to block that? Where is your coastal flooding report? In any case you won’t get a permit to build low enough to be at risk of coastal flooding. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Structural design questions to raise house 3m 9Apr 27, 2022 5:24 pm Post and beam foundation in situ, then you can brick up or frame your walls on top of the beams. For flooring install couple of layers of yellow tongue (one over the beams and one under the beams) with insulation in between. Alternatively, Bondek or Speedfloor based suspended slab, but you would still need to insulate under. Re: Structural design questions to raise house 3m 10Apr 30, 2022 10:06 am gommeqld So for a 15x25m area = 375m2 that gives a cost of $375,000 and precast gives a cost of $750,000 to $1.125M. Surely I misread something? If not then concrete cast on site or pre cast is certainly not an option. I'm guessing that's a typo and is a "timber" home. Fair question but I'm looking to avoid coastal flooding on this site so I'm assuming (but I could be wrong of course) that a steel or concrete subfloor structure will be more robust. Sound proofing is also a high priority so again I'm wondering if concrete has an advantage over steel and timber for flooring. You need engineering drawings and quantities Why would you put a timber frame or brick veneer home over a concrete platform structure, it doesn't make sense to me? If its precast you would continue the whole house wall in precast up to the roof. Search the codes and property material for Fire, Durability, various other loading factors or better still hire a local design engineer OT the Architects and bluescope had a design competition after the previous Brisbane flooding's. Nothing become of it , it was just a Marketing stunt, Fake coloured image rendering, and Hot air, etc,etc. nuf said Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs ok thanks - yes was wondering if that should have been listed as Option Three! 2 7772 i had the my concreters concrete right up to the fence. I have pits all along my path, so the water tends to drain away from the house and into the pits. There's only one… 7 12827 |