Browse Forums General Discussion 1 Nov 01, 2021 9:13 pm Hi guys, updates after receiving the geotect report. Please see the notes from the geotect engineer. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ My architect is saying now both strip footing and raft slab are fine for my site, instead of screw Piling . Which one should I choose then? Any suggestions are welcome 🤗 Many thanks, Judy Re: Strip footing or raft slab? 2Nov 02, 2021 8:01 am I would prefer strip footings and stumps with a timber floor 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: Strip footing or raft slab? 3Nov 02, 2021 11:37 am building-expert I would prefer strip footings and stumps with a timber floor Hi thanks for the advice. Any reason for the preference? I’m building a double brick double storey house with concrete floor, so it’s pretty heavy. Thanks, Judy Re: Strip footing or raft slab? 4Nov 02, 2021 1:38 pm I have both, just like timber floors better 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: Strip footing or raft slab? 5Nov 02, 2021 2:52 pm Savagepuppy building-expert I would prefer strip footings and stumps with a timber floor Hi thanks for the advice. Any reason for the preference? I’m building a double brick double storey house with concrete floor, so it’s pretty heavy. Thanks, Judy Judy if you are going double brick definitely go with the raft slab due to the weight. I was literally having this conversation with my engineering team on another build last week. Good luck Simeon Architectural Homes & Duplexes - specialising in custom designing homes to your budget Get a Free Onsite Consultation Today or send a PM for information, questions or advice. Re: Strip footing or raft slab? 6Nov 02, 2021 3:48 pm I would excavate for strip footings and internal piers down to rock then use blinding. Once you bear footings and pads on rock weight does not matter and you won’t have cracking from foundation movement. There are many solid brick two storey homes that stood the test of time. 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: Strip footing or raft slab? 7Nov 04, 2021 11:36 am Ashington Homes Savagepuppy building-expert I would prefer strip footings and stumps with a timber floor Hi thanks for the advice. Any reason for the preference? I’m building a double brick double storey house with concrete floor, so it’s pretty heavy. Thanks, Judy Judy if you are going double brick definitely go with the raft slab due to the weight. I was literally having this conversation with my engineering team on another build last week. Good luck Simeon Hi Simeon, Thanks for the advice, I actually got a second engineer to make sure the plan was on track, he also said that raft slab was a better option. Good to know that’s confirmed by your whole team of engineers 😂 Many thanks, Judy Re: Strip footing or raft slab? 8Nov 04, 2021 11:44 am building-expert I would excavate for strip footings and internal piers down to rock then use blinding. Once you bear footings and pads on rock weight does not matter and you won’t have cracking from foundation movement. There are many solid brick two storey homes that stood the test of time. Thanks for the advice again. My second engineer did emphasise the importance of piers to rock 🪨 he also said If I use face brick then it’s better to do strip footing, but if I render the house, which is what I’m planning to do, then raft slab is better. He also said because my land is very small, maybe raft slab would work. I’m not sure if I fully understand all these… Many thanks, Judy Re: Strip footing or raft slab? 9Nov 04, 2021 12:07 pm Hi Judy, thanks for your reply. Glad it's working out for you. The raft slab whilst expensive will move with the land and be able to take the weight of the structure that you are proposing. They key for your builder will be finding a good concreter who can build it properly, as raft slabs are not that common in Sydney. I think Building Expert's advice was great as well. There is a builder in my area who only builds with this method, a bit old school but works a treat. Anyway, best of luck Simeon Architectural Homes & Duplexes - specialising in custom designing homes to your budget Get a Free Onsite Consultation Today or send a PM for information, questions or advice. Re: Strip footing or raft slab? 10Nov 04, 2021 12:17 pm Savagepuppy building-expert I would excavate for strip footings and internal piers down to rock then use blinding. Once you bear footings and pads on rock weight does not matter and you won’t have cracking from foundation movement. There are many solid brick two storey homes that stood the test of time. Thanks for the advice again. My second engineer did emphasise the importance of piers to rock 🪨 he also said If I use face brick then it’s better to do strip footing, but if I render the house, which is what I’m planning to do, then raft slab is better. He also said because my land is very small, maybe raft slab would work. I’m not sure if I fully understand all these… Many thanks, Judy Footings is one thing, slab is another. They are not self excluding ie raft slab usually comes on top of the strip footings. Re: Strip footing or raft slab? 11Nov 04, 2021 6:35 pm I think it's engineering vs common sense It does not seem sensible to me to put a raft slab to float on loose sand when rock is down 1.7m or less Raft slabs are engineered structures and require contractors with skills to construct and are very expensive once you factor in site costs and prone to failure for variety of reasons. There is no engineering in strip footings and pads that are taken down to rock, will last forever and is probably cheaper 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: Strip footing or raft slab? 12Nov 05, 2021 5:27 am Ashington Homes Hi Judy, thanks for your reply. Glad it's working out for you. The raft slab whilst expensive will move with the land and be able to take the weight of the structure that you are proposing. They key for your builder will be finding a good concreter who can build it properly, as raft slabs are not that common in Sydney. I think Building Expert's advice was great as well. There is a builder in my area who only builds with this method, a bit old school but works a treat. Anyway, best of luck Simeon Hi Simeon, Thanks for the advice again. When you say the raft slab will move with the land , any chance there will be subsidence? As that’s the problem with my current house. I was torn between fixing the current house or kdr, was told very hard to fix subsidence with double brick house. Cheers, Judy Re: Strip footing or raft slab? 13Nov 05, 2021 5:36 am alexp79 Savagepuppy building-expert I would excavate for strip footings and internal piers down to rock then use blinding. Once you bear footings and pads on rock weight does not matter and you won’t have cracking from foundation movement. There are many solid brick two storey homes that stood the test of time. Thanks for the advice again. My second engineer did emphasise the importance of piers to rock 🪨 he also said If I use face brick then it’s better to do strip footing, but if I render the house, which is what I’m planning to do, then raft slab is better. He also said because my land is very small, maybe raft slab would work. I’m not sure if I fully understand all these… Many thanks, Judy Footings is one thing, slab is another. They are not self excluding ie raft slab usually comes on top of the strip footings. For some reason, my architect said these are the two options. Sorry in my previous post, ‘If I use face brick then it’s better to do strip footing, but if I render the house, which is what I’m planning to do, then raft slab is better. He also said because my land is very small. Maybe raft slab’ would work.’ That comment was from my architect. I might try to post the two options plan here . Cheers Judy Re: Strip footing or raft slab? 14Nov 05, 2021 5:41 am building-expert I think it's engineering vs common sense It does not seem sensible to me to put a raft slab to float on loose sand when rock is down 1.7m or less Raft slabs are engineered structures and require contractors with skills to construct and are very expensive once you factor in site costs and prone to failure for variety of reasons. There is no engineering in strip footings and pads that are taken down to rock, will last forever and is probably cheaper So raft slabs are more prone to failure? 😨 Re: Strip footing or raft slab? 15Nov 05, 2021 5:51 am Savagepuppy building-expert I think it's engineering vs common sense It does not seem sensible to me to put a raft slab to float on loose sand when rock is down 1.7m or less Raft slabs are engineered structures and require contractors with skills to construct and are very expensive once you factor in site costs and prone to failure for variety of reasons. There is no engineering in strip footings and pads that are taken down to rock, will last forever and is probably cheaper So raft slabs are more prone to failure? 😨 Now my architect is asking the second engineer why screw piling is not chosen being sand? The first engineer‘S initial plan was screw piling without the geotect report . I’m so confused 😐 Re: Strip footing or raft slab? 16Nov 05, 2021 6:20 am Savagepuppy building-expert I think it's engineering vs common sense It does not seem sensible to me to put a raft slab to float on loose sand when rock is down 1.7m or less Raft slabs are engineered structures and require contractors with skills to construct and are very expensive once you factor in site costs and prone to failure for variety of reasons. There is no engineering in strip footings and pads that are taken down to rock, will last forever and is probably cheaper So raft slabs are more prone to failure? 😨 Yes I have seen hundreds of slab failures. I am defining failure when movement of slab exceeds allowable construction tolerances 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: Strip footing or raft slab? 18Nov 05, 2021 10:38 am Yes, you can have strip footings and then put on top stumps and cover with yellow tongue (still sounds like a cheapish farm house solution to me rather than prominent double brick residence) or you can put raft slab on top of your strip footings. There also other ways (arguably cheaper and more reliable than raft) e.g. having suspended slab with Bondek or Speedfloor over your strip footings. Re: Strip footing or raft slab? 19Nov 05, 2021 10:22 pm building-expert Savagepuppy building-expert I think it's engineering vs common sense It does not seem sensible to me to put a raft slab to float on loose sand when rock is down 1.7m or less Raft slabs are engineered structures and require contractors with skills to construct and are very expensive once you factor in site costs and prone to failure for variety of reasons. There is no engineering in strip footings and pads that are taken down to rock, will last forever and is probably cheaper So raft slabs are more prone to failure? 😨 Yes I have seen hundreds of slab failures. I am defining failure when movement of slab exceeds allowable construction tolerances That sounds pretty bad. Does that mean there will be subsidence when movement of slab exceeds allowable construction tolerances? That’s the lat problem I want to have 😖😟 Re: Strip footing or raft slab? 20Nov 05, 2021 10:23 pm alexp79 https://cornellengineers.com.au/what-is-a-raft-slab/ Many thanks, really helpful yep sounds good make the footing bigger to to allow for the pipe in the middle 3 7362 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 10326 I've dug some footings to embed a post anchor into. My holes are around 450mm deep which I'll put a 200mm stirrup into. The bottom of these holes seem firm enough. … 0 3391 |