Browse Forums Building A New House 1 May 28, 2021 1:42 pm Hello to all, I am currently trying to find a reliable Structural and Forensic engineer/consultation company that does inspections for Western Melbourne suburbs too. I am currently building a house with a custom builder. The soil test classified it as H2, and the slab was engineered to have 300mm waffle pods with 85mm slab on top. This is for a double storey dwelling. From what I have been reading, 300mm waffle pods with 85mm slab are more of a H1 slab, for H2 375mm waffle pods and 100mm slabs on top are used. I am not a structural engineer and by no means I am questioning the engineer who designed it. However, after the foundation was poured, it developed a large number of long hairline cracks (37). The builder has told me these are non-structural defects and there is nothing wrong with the slab. It has been 7 months now since the slab was poured, and the builder is nearing the stage to install floor board in the coming months/weeks. I want to get an inspection done by a structural engineer before that, to have peace of mind. Also, the lot is on a sloping land and would need retaining walls later (builder is not installing them). I also have questions on what additional plumbing measures (pits/additional drains, etc) should I take to ensure that moisture does not impacts the slab. I tried to engage directly with the engineering company that the builder contracted for design. They are not engaging with me directly as they have a contract with the builder, and I am the builder's customer. It is difficult to shortlist companies/engineers just by reading online reviews. I would highly appreciate if I can get some guidance on how to search for a structural engineer and if some of you had good experiences with any companies in the past. Thank you! Re: Structural and Forensic engineering consultation company 2May 31, 2021 10:37 am Hi sid16, H1/H2 waffle slab heights are the same (300+85) and only reinforcements are different, in regards to retaining walls, you need to have agi pipes behind/front of the retaining wall depending on the type, then these pipes need to be connected to drainage system via silt pit, so these should have been considered by your builder/engineer, DM me your design documentation and I have a quick check for you. Re: Structural and Forensic engineering consultation company 4May 31, 2021 2:44 pm strannik Are you sure about 300+85? We just had a soil report done for our block and the form lists H1/H2 as 400, which assume is 300+100. Min. is 300+85, the height will be specified by your structural engineer and not soil tester, in your case it should be 300pods + 100 slab thickness which is better. Re: Structural and Forensic engineering consultation company 5May 31, 2021 3:02 pm Structural.Review strannik Are you sure about 300+85? We just had a soil report done for our block and the form lists H1/H2 as 400, which assume is 300+100. Min. is 300+85, the height will be specified by your structural engineer and not soil tester, in your case it should be 300pods + 100 slab thickness which is better. Thanks for clarifying. The follow up question I have on that. If for argument's sake the structural engineer specifies the height as 385 for H2 soil, is it worth pushing for 400 (assuming cost isn't an issue). Or even 475 (E class)? Although the latter would probably be much higher cost difference. Sorry for hijacking OP's thread but I had very similar questions floating in my head and I want to make sure we get it sorted before the slab is poured (or contract is signed for that matter). Re: Structural and Forensic engineering consultation company 6May 31, 2021 3:18 pm Increasing slab height will improve the overall performance significantly, 385 is just the absolute Min. required height, you can ask your structural Engineer and building designer to specify 100thick slab ILO 85mm. The overall performance of the slab depends on the competency of everyone involved in your project (Engineer, builder, building surveyor), in summary; Make sure during the build, there is adequate drainage around the house and water is not ponding against the slab, all edge beams need to be deepen into natural soil/controlled fill (this is a frequently missed) or supported on piers , do not plant trees or if you have existing trees, your engineer should take that into consideration. Also read "Foundation Maintenance and Footing Performance: A Homeowner's Guide" http://www.residentialreports.com.au/wp ... enance.pdf Re: Structural and Forensic engineering consultation company 7May 31, 2021 5:22 pm Does the 'no planting' advice go just for trees or shrubs too? I've been going through display houses in that area, and a lot of them seem to have a bunch of various shrubs/succulents planted all around the edges of the lot against the fence and sometimes even against the house wall. as most of them are small lots, the houses are usually being built to the minimum allowed setbacks (usually 1.2-1.8m from the wall). Which (after reading a lot of threads on this forum) kinda made me wonder if it's usually not a problem, or the builders of those display houses simply don't care as to what happens after they offload them. Also made me question our tree choices in our current house (with S soil), and whether i should pull out the avocado and pomegranate before turning it into rental, but that's a separate story Re: Structural and Forensic engineering consultation company 8May 31, 2021 7:54 pm Structural.Review Hi sid16, H1/H2 waffle slab heights are the same (300+85) and only reinforcements are different, in regards to retaining walls, you need to have agi pipes behind/front of the retaining wall depending on the type, then these pipes need to be connected to drainage system via silt pit, so these should have been considered by your builder/engineer, DM me your design documentation and I have a quick check for you. Thanks a lot Structural.Review! Unfortunately neither the builder, nor the structural engineer has added agi pipes and the silt pit as you mentioned. The house adjacent to mine on the downward slope has the silt pits, as you mentioned. I wonder why did the builder did not consider the same for my block too. I am sharing the design document and some photographs with you. Once again, thanks a lot for taking out time to help me out. This means a lot! Re: Structural and Forensic engineering consultation company 9May 31, 2021 8:25 pm Structural.Review Increasing slab height will improve the overall performance significantly, 385 is just the absolute Min. required height, you can ask your structural Engineer and building designer to specify 100thick slab ILO 85mm. The overall performance of the slab depends on the competency of everyone involved in your project (Engineer, builder, building surveyor), in summary; Make sure during the build, there is adequate drainage around the house and water is not ponding against the slab, all edge beams need to be deepen into natural soil/controlled fill (this is a frequently missed) or supported on piers , do not plant trees or if you have existing trees, your engineer should take that into consideration. Also read "Foundation Maintenance and Footing Performance: A Homeowner's Guide" http://www.residentialreports.com.au/wp ... enance.pdf Thanks for the information Structural.Review. I have DM'd you the photos and the design document. Currently it shows to be in "outbox", I am not sure why. Do let me know if you were able to receive them, if not, I'll upload them on google drive and share a link on the forum. Thanks again Re: Structural and Forensic engineering consultation company 10May 31, 2021 10:50 pm strannik Does the 'no planting' advice go just for trees or shrubs too? I've been going through display houses in that area, and a lot of them seem to have a bunch of various shrubs/succulents planted all around the edges of the lot against the fence and sometimes even against the house wall. as most of them are small lots, the houses are usually being built to the minimum allowed setbacks (usually 1.2-1.8m from the wall). Which (after reading a lot of threads on this forum) kinda made me wonder if it's usually not a problem, or the builders of those display houses simply don't care as to what happens after they offload them. Also made me question our tree choices in our current house (with S soil), and whether i should pull out the avocado and pomegranate before turning it into rental, but that's a separate story They build display houses better generally, deeper footings etc., I have designed couple of them and all supported on piers as I knew that there will be plants and trees around it, in short, you don't want to cause abnormal moisture condition, you need to water plants right? that's enough to cause slab heave. If your site has been classified as S, it is unlikely that trees will cause you any problem, don't remove the trees if they haven't caused any problem yet, you just make it worst by removing them. Assuming you've modelled the TB8, TB10, TB12, TB2 & J1 joists/LVLs there, it appears as per drawing to me. There maybe should be an additional J1 between TB10 and T12 if… 3 31780 Thanks for all replies. I just noticed now the pictures I added to post right on top of page were wrong. I attached pictures showing "current" and my "suggested" floor… 9 14627 |