Browse Forums General Discussion 1 Jun 09, 2021 8:12 pm Hi All, My new home is under construction and the site had a cut/fill. On the side of the fill, I have noticed land subsiding at few places. The soil classification is P and slab is Waffle Pod with screw piers every few meters. I am not sure how serious the issue is and what is the best way to proceed. In hindsight I feel I should have got the slab inspection done but it is too late now. Any help will be highly appreciated. Thanks in advance Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Land subsiding - Please Help 2Jun 17, 2021 12:51 am Looks like whoever is certifying your build has marked this. I was told that gaps like this allow water to flow unimpeded under the slab so my recollection is they should be back filled Best to call the engineer and/or building surveyor/ certifier to ask how this should be rectified and then you can check the builder does this. My building consultant and surveyor also identified this as an issue. The builder wasn’t concerned due to the deep piles or piers... I cannot recall now. I had to persist to have the backfilling recommended completed. Re: Land subsiding - Please Help 3Jun 17, 2021 11:20 am From AS 2870: "Surface drainage shall be designed and constructed to avoid water ponding against or near the footing. The ground in the immediate vicinity of the perimeter footing, including the ground uphill from the slab on cut-and-fill sites, shall be graded to fall 50 mm minimum away from the footing over a distance of 1 m and shaped to prevent ponding of water. Where filling is placed adjacent to the building, the filling shall be compacted and graded to ensure drainage of water away from the building." Drainage is the main failure in waffle slabs, get it fixed by builder ASAP. Re: Land subsiding - Please Help 4Jun 17, 2021 4:07 pm Gaudi Looks like whoever is certifying your build has marked this. I was told that gaps like this allow water to flow unimpeded under the slab so my recollection is they should be back filled Best to call the engineer and/or building surveyor/ certifier to ask how this should be rectified and then you can check the builder does this. My building consultant and surveyor also identified this as an issue. The builder wasn’t concerned due to the deep piles or piers... I cannot recall now. I had to persist to have the backfilling recommended completed. Hi Gaudi, Thanks for inputs. The site supervisor is saying something similar that there is no cause of concern as it is on screw piers. He seems to be suggesting that back filling is my responsibility. Cheers Re: Land subsiding - Please Help 5Jun 17, 2021 4:08 pm Structural.Review From AS 2870: "Surface drainage shall be designed and constructed to avoid water ponding against or near the footing. The ground in the immediate vicinity of the perimeter footing, including the ground uphill from the slab on cut-and-fill sites, shall be graded to fall 50 mm minimum away from the footing over a distance of 1 m and shaped to prevent ponding of water. Where filling is placed adjacent to the building, the filling shall be compacted and graded to ensure drainage of water away from the building." Drainage is the main failure in waffle slabs, get it fixed by builder ASAP. Thanks for all your help mate. Re: Land subsiding - Please Help 6Jun 17, 2021 4:49 pm [quote= He seems to be suggesting that back filling is my responsibility. Cheers[/quote] I have been thinking of building again in the next 1-2 years. Your statement has reminded me how much hard work the build was. Remember throughout your build that the site supervisor is usually not that knowledgeable about Australian standards..... and in many cases neither is the building manager. Keep taking photos! Re: Land subsiding - Please Help 7Jun 17, 2021 5:01 pm Aussieninja Gaudi Looks like whoever is certifying your build has marked this. I was told that gaps like this allow water to flow unimpeded under the slab so my recollection is they should be back filled Best to call the engineer and/or building surveyor/ certifier to ask how this should be rectified and then you can check the builder does this. My building consultant and surveyor also identified this as an issue. The builder wasn’t concerned due to the deep piles or piers... I cannot recall now. I had to persist to have the backfilling recommended completed. Hi Gaudi, Thanks for inputs. The site supervisor is saying something similar that there is no cause of concern as it is on screw piers. He seems to be suggesting that back filling is my responsibility. Cheers I have sent you some more information regarding this, but for everyone else reading this topic, backfilling should be carried out to engineers specification by builder, a home owner do not have any responsibility for backfilling. Re: Land subsiding - Please Help 8Jun 17, 2021 5:34 pm Structural.Review Aussieninja Gaudi Looks like whoever is certifying your build has marked this. I was told that gaps like this allow water to flow unimpeded under the slab so my recollection is they should be back filled Best to call the engineer and/or building surveyor/ certifier to ask how this should be rectified and then you can check the builder does this. My building consultant and surveyor also identified this as an issue. The builder wasn’t concerned due to the deep piles or piers... I cannot recall now. I had to persist to have the backfilling recommended completed. Hi Gaudi, Thanks for inputs. The site supervisor is saying something similar that there is no cause of concern as it is on screw piers. He seems to be suggesting that back filling is my responsibility. Cheers I have sent you some more information regarding this, but for everyone else reading this topic, backfilling should be carried out to engineers specification by builder, a home owner do not have any responsibility for backfilling. You have been extremely helpful mate. Can't express my gratitude in words. Thank you so much for your valuable help and advice. Re: Land subsiding - Please Help 9Jun 17, 2021 5:39 pm Gaudi [quote= He seems to be suggesting that back filling is my responsibility. Cheers I have been thinking of building again in the next 1-2 years. Your statement has reminded me how much hard work the build was. Remember throughout your build that the site supervisor is usually not that knowledgeable about Australian standards..... and in many cases neither is the building manager. Keep taking photos![/quote] I completely agree building is a painful process. Thanks for your advice. I need to keep that in mind as it seems I have been relying too much on my supervisor. Thankyou so much 😀 I've decided on White on white for doors and trims, White on white 50% on ceiling and Mt buller for walls. Fingers crossed it will look OK 😀 2 3611 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 9683 All 3 items listed are defects and are of concern. Please seek qualified independent inspector and/or legal advice for your state. 1 6263 |