Browse Forums Building A New House Re: Footing Variation with controlled fill 21Apr 15, 2015 8:54 pm A lot of your extra money will be going into the concrete piers whereas the blocks next door may have designed for a rigid slab with no piers so that could be your big variation in costs.It is a engineers call which footing type the design for.Maybe there were no trees on the other blocks who knows.The only way you will find out is if you ask the engineers the reason for their design. Re: Footing Variation with controlled fill 22Apr 15, 2015 9:05 pm LittleSuzi Thank you for your post. Yes, it is waffle slab with brick veneer . My footing schedule: Type Beam Size(mm)WidthXDepth Reinforcement top bottom Hangers Type A 250X650 1-N24 1-N24 W10 AT 1000 CTS Type B 250X650 1-N20 1-N24 W10 AT 1000 CTS Type C 250X550 1-N20 1-N24 W8 AT 1000 CTS This doesn't look like a waffle slab. It's the same sort of specification as ours, which is for a raft slab with beams, which seems the norm in Adelaide. That accounts for them being deeper, as there aren't as many beams as a waffle slab has. How does it compare to the other house on the street? Our site is P / H2-D, and most of our beams are 300 x 900, on about a 3 metre grid. For 300m2, they're charging us around $20k for the footings, $5k for site preparation and another $5k for spoil removal. Our builder seems to allow more in the standard footing though. Another builder had quoted us an estimate of $40k for 250x750 footings, which is not so far off the cost you have per square metre. Re: Footing Variation with controlled fill 23Apr 15, 2015 9:13 pm What I don't understand is why builder is charging extra variation for footing costs when the contract has already been signed and builder has had opportunity to review foundation data and price accordingly. Any other foundation cost is builders risk and in Vic at least prohibits further variations unless there are exceptional circumstances. 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: Footing Variation with controlled fill 24Apr 15, 2015 9:25 pm Now I am worried we are on a P site ED soil with 200x900 beams.... Re: Footing Variation with controlled fill 25Apr 15, 2015 9:28 pm oneJohn LittleSuzi Thank you for your post. Yes, it is waffle slab with brick veneer . My footing schedule: Type Beam Size(mm)WidthXDepth Reinforcement top bottom Hangers Type A 250X650 1-N24 1-N24 W10 AT 1000 CTS Type B 250X650 1-N20 1-N24 W10 AT 1000 CTS Type C 250X550 1-N20 1-N24 W8 AT 1000 CTS This doesn't look like a waffle slab. It's the same sort of specification as ours, which is for a raft slab with beams, which seems the norm in Adelaide. That accounts for them being deeper, as there aren't as many beams as a waffle slab has. How does it compare to the other house on the street? Our site is P / H2-D, and most of our beams are 300 x 900, on about a 3 metre grid. For 300m2, they're charging us around $20k for the footings, $5k for site preparation and another $5k for spoil removal. Our builder seems to allow more in the standard footing though. Another builder had quoted us an estimate of $40k for 250x750 footings, which is not so far off the cost you have per square metre. I have been told that they no longer use waffles in Adelaide isn't that interesting after they originally came from there now the rest of Australia has to deal with them. Re: Footing Variation with controlled fill 26Apr 15, 2015 10:06 pm oneJohn LittleSuzi Thank you for your post. Yes, it is waffle slab with brick veneer . My footing schedule: Type Beam Size(mm)WidthXDepth Reinforcement top bottom Hangers Type A 250X650 1-N24 1-N24 W10 AT 1000 CTS Type B 250X650 1-N20 1-N24 W10 AT 1000 CTS Type C 250X550 1-N20 1-N24 W8 AT 1000 CTS This doesn't look like a waffle slab. It's the same sort of specification as ours, which is for a raft slab with beams, which seems the norm in Adelaide. That accounts for them being deeper, as there aren't as many beams as a waffle slab has. How does it compare to the other house on the street? Our site is P / H2-D, and most of our beams are 300 x 900, on about a 3 metre grid. For 300m2, they're charging us around $20k for the footings, $5k for site preparation and another $5k for spoil removal. Our builder seems to allow more in the standard footing though. Another builder had quoted us an estimate of $40k for 250x750 footings, which is not so far off the cost you have per square metre. Hi oneJohn, I saw Waffle slab on my initial contract. I thought it is still the same. Maybe because the engineering has redesigned my footing into reft slab. Just comparing the soil borelog of my bf who is building serval houses away from mine. both soil description very close,shrinkage index very close, my bearing capability even slightly better than his. but my site classification is worse. Interesting! I am going to ask the engineering company tomorrow. Re: Footing Variation with controlled fill 27Apr 15, 2015 10:14 pm We're P based on demolition of existing house, plus trees and fill. I can't see any piers on the footing diagram, though they do specify there should be piers if there's a sewer service run close to the slab. The waffle may be the "standard" footing they price you on, and the classification has likely moved you into a raft instead. Re: Footing Variation with controlled fill 28Apr 16, 2015 8:43 am LittleSuzi cornellengineers Hi LittleSuzi I'm guessing your slab is a waffle slab with brick veneer walls? If I'm wrong let me know. According to AS2870 (the 'book' of standard waffle slab designs), a H2-D slab will be 460 high compared to a H1-D slab being only 385 high. That extra height (extra strength) results in extra concrete and extra fill around your house when it is complete. I think that will account for some of your cost increase. Compared to a Class S or Class M site, which is a 310 high slab and much lighter reinforcement (same brick veneer) the rest of your cost increase is accounted for. Some of your costs won't change (the concreter still has to turn up) so make sure your builder can itemise the price rise. Matt Cornell Hello Matt Thank you for your post. Yes, it is waffle slab with brick veneer . My footing schedule: Type Beam Size(mm)WidthXDepth Reinforcement top bottom Hangers Type A 250X650 1-N24 1-N24 W10 AT 1000 CTS Type B 250X650 1-N20 1-N24 W10 AT 1000 CTS Type C 250X550 1-N20 1-N24 W8 AT 1000 CTS Looks my footing depth is 650mm,much higher than the standard H2-D slab. Is that nessessory to put that much extra depth of slab? Sorry for the silly questions.haha Cheers, Suzi Hi suzzie Sorry,most people wont see the funny side as they dont have the additional funds your options now as I see them are 1. Hire another engineer could cost more than its worth 2. Try to follow the codes which incidently are inadequate in your case anyway? 3. Ask the salesman to pay the difference as he put you in this mess anyway 4. As I have already posted try to reason with your builder.. but somehow you've handed over a deposit and he now holds the whip hand. The engineer is also guided by the builder as well 5. Walk out loose your deposit...a valuable lesson learnt. Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Footing Variation with controlled fill 29Apr 19, 2015 4:49 pm oneJohn We're P based on demolition of existing house, plus trees and fill. I can't see any piers on the footing diagram, though they do specify there should be piers if there's a sewer service run close to the slab. The waffle may be the "standard" footing they price you on, and the classification has likely moved you into a raft instead. Yes, oneJohn. I think you are right. How is your building status now? Re: Footing Variation with controlled fill 30Apr 19, 2015 4:52 pm StructuralBIMGuy LittleSuzi cornellengineers Hi LittleSuzi I'm guessing your slab is a waffle slab with brick veneer walls? If I'm wrong let me know. According to AS2870 (the 'book' of standard waffle slab designs), a H2-D slab will be 460 high compared to a H1-D slab being only 385 high. That extra height (extra strength) results in extra concrete and extra fill around your house when it is complete. I think that will account for some of your cost increase. Compared to a Class S or Class M site, which is a 310 high slab and much lighter reinforcement (same brick veneer) the rest of your cost increase is accounted for. Some of your costs won't change (the concreter still has to turn up) so make sure your builder can itemise the price rise. Matt Cornell Hello Matt Thank you for your post. Yes, it is waffle slab with brick veneer . My footing schedule: Type Beam Size(mm)WidthXDepth Reinforcement top bottom Hangers Type A 250X650 1-N24 1-N24 W10 AT 1000 CTS Type B 250X650 1-N20 1-N24 W10 AT 1000 CTS Type C 250X550 1-N20 1-N24 W8 AT 1000 CTS Looks my footing depth is 650mm,much higher than the standard H2-D slab. Is that nessessory to put that much extra depth of slab? Sorry for the silly questions.haha Cheers, Suzi Hi suzzie Sorry,most people wont see the funny side as they dont have the additional funds your options now as I see them are 1. Hire another engineer could cost more than its worth 2. Try to follow the codes which incidently are inadequate in your case anyway? 3. Ask the salesman to pay the difference as he put you in this mess anyway 4. As I have already posted try to reason with your builder.. but somehow you've handed over a deposit and he now holds the whip hand. The engineer is also guided by the builder as well 5. Walk out loose your deposit...a valuable lesson learnt. Thank you Matt I am waiting for the builder's reponse so far. And , I will make a decision soon. Thank you for helping me analyse this footing variation issue. Nice weekend:) Re: Footing Variation with controlled fill 31Apr 19, 2015 7:55 pm Have you questioned why it went to contract without a fixed price for slab? Did they only have an allowance set for the slab? I wouldn't consider our letter of tender until we had fixed pricing for slab and all others. As it is we have an allowance for acoustics and made sure that was well over what we would need as a safe guard. Versaloc is a mortarless besser block system that still needs a properly engineered footing. If you just do a 400x200 footing it will fail in time. At 17m long you need it… 1 17307 yep sounds good make the footing bigger to to allow for the pipe in the middle 3 7314 PM me your email. I have a build excavation calculator you can use based on your plans to double check what your builder is telling you. Cheers Simeon 1 10236 |