Browse Forums Building Standards; Getting It Right! Re: Wall cracks, building footpath as per CSIRO BTF18 21Jan 29, 2022 7:52 am The problem is that if the concrete dumps water at the far edge of the concrete then this can make the clay swell lifting the edge and tilt the concrete pavement back towards the house. Rainwater will then run towards the house causing water to seep into the clay next to your footing and create slab heave. There are a couple of alternatives, one is to have the concrete paving with inlet drains incorporated into it with the paving sloping towards the drains. This will require professional plumbing to install the drains before the paving is done and a concreter who does his job properly. The other alternative is to have a channel type spoon drain running parallel to the house along the outer edge of the concrete path and sloping towards an inlet drain that is connected to your stormwater system. Another option is not to have a concrete path and grade the ground level away from the house then place builders plastic over the sloping ground level. You can then put soil on top of the plastic and the plastic will direct moisture away from the house even when it is below the ground level and not visible. Don't use any material on top of the plastic that might puncture the plastic. Re: Wall cracks, building footpath as per CSIRO BTF18 22Jan 29, 2022 10:06 am groundzero The problem is that if the concrete dumps water at the far edge of the concrete then this can make the clay swell lifting the edge and tilt the concrete pavement back towards the house. Rainwater will then run towards the house causing water to seep into the clay next to your footing and create slab heave. There are a couple of alternatives, one is to have the concrete paving with inlet drains incorporated into it with the paving sloping towards the drains. This will require professional plumbing to install the drains before the paving is done and a concreter who does his job properly. The other alternative is to have a channel type spoon drain running parallel to the house along the outer edge of the concrete path and sloping towards an inlet drain that is connected to your stormwater system. Another option is not to have a concrete path and grade the ground level away from the house then place builders plastic over the sloping ground level. You can then put soil on top of the plastic and the plastic will direct moisture away from the house even when it is below the ground level and not visible. Don't use any material on top of the plastic that might puncture the plastic. Thanks so much for the detail reply! Would you have any pictures of what the above solutions would look like? Sounds like the last option may be the cheapest one. Re: Wall cracks, building footpath as per CSIRO BTF18 23Jan 29, 2022 2:45 pm Write reply... Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Definitely the cheapest option but doesn't remove the excess moisture just moves it away from the house. Ideally an agi pipe would be incorporated at the low point of the builders plastic. Hopefully your neighbour has something similar.The graded ground and the plastic must slope away from the house or this could have the reverse effect and create slab heave which I have seen happen many times. Re: Wall cracks, building footpath as per CSIRO BTF18 24Jan 29, 2022 3:24 pm groundzero Write reply... Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Definitely the cheapest option but doesn't remove the excess moisture just moves it away from the house. Ideally an agi pipe would be incorporated at the low point of the builders plastic. Hopefully your neighbour has something similar.The graded ground and the plastic must slope away from the house or this could have the reverse effect and create slab heave which I have seen happen many times. That is brilliant, thanks so much! Would this work normally be done by landscapers? Would 50mm fall be sufficient for the graded soil and builder's plastic? Lastly, the wall cracks (2-3mm) were in my property in 2017 when we bought it (not sure if they were of the same size or smaller), and who knows how long they have been there. Would the graded soil, without agi pipe, be sufficient? Or maybe a silly question, is it ok if I just monitor the cracks (over the next 12-24 months) without even worrying about the concrete footpath and drainage, and if/when they get bigger grade the soil and install drainage? My plan is to sell the house in 10 years and considering all the costs of the work to be done (20k for footpath, drainage, fixing roof plumbing and relevelling by pack and jack) I am even considering selling this house now. Thank so much again 😀 Re: Wall cracks, building footpath as per CSIRO BTF18 25Jan 31, 2022 7:59 pm groundzero Write reply... Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Definitely the cheapest option but doesn't remove the excess moisture just moves it away from the house. Ideally an agi pipe would be incorporated at the low point of the builders plastic. Hopefully your neighbour has something similar.The graded ground and the plastic must slope away from the house or this could have the reverse effect and create slab heave which I have seen happen many times. Hi mate, would you be able to advise on how to seal the gap between the house and the builders plastic? And also is it sufficient if I use builders plastic of 0.2mm and use 2 layers of it? Re: Wall cracks, building footpath as per CSIRO BTF18 26Jan 31, 2022 8:04 pm 2 layers would be better than one not sure about the best way to seal it to the slab edge or brickwork but there will be good products out there that would suit. Re: Wall cracks, building footpath as per CSIRO BTF18 27Feb 01, 2022 7:01 am SaveH2O The CSIRO publication is an un-updated guide but while it is not legislated and has no legal standing, the content is predominately good. An engineer should however know better than to reference a Guide and not knowing the regulation for what he is specifically referencing in that guide is non infigo. I actually spoke with Steve Lawler, the guy who write that guide as there was a conflict between it and the ncc at the time. His words were, paraphrased, there's been a lot that's been learned and changed since he wrote the guide, and one should follow what the ncc states. The ncc didn't have the information the guide has back in the day. Dark matter scientist, can breathe underwater, mind reader and can freeze matter just by willing it. Trust me, its in my sig. Re: Wall cracks, building footpath as per CSIRO BTF18 28Feb 01, 2022 8:24 am Noname "The ncc didn't have the information the guide has back in the day." That's right, the NCC didn't address the slope at the time but Steve Lawler had the knowledge and common sense understanding to know how important it was to do so. The problem is that the CSIRO Guide wasn't updated when the NCC introduced a steeper slope requirement but many builders continued giving their customers the CSIRO Guide without advising of the NCC steeper slope mandate. It wasn't until recently that the NCC became freely available, previously it was an expensive document that was updated annually, the reason for its small annual sales back then. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Wall cracks, building footpath as per CSIRO BTF18 29Feb 01, 2022 8:57 am SaveH2O Noname "The ncc didn't have the information the guide has back in the day." That's right, the NCC didn't address the slope at the time but Steve Lawler had the knowledge and common sense understanding to know how important it was to do so. The problem is that the CSIRO Guide wasn't updated when the NCC introduced a steeper slope requirement but many builders continued giving their customers the CSIRO Guide without advising of the NCC steeper slope mandate. It wasn't until recently that the NCC became freely available, previously it was an expensive document that was updated annually, the reason for its small annual sales back then. Yep, pretty much the reason i contacted him in the first place. I had a scenario with my first builder years ago that said the path they installed was in line with the guide (it wasn't by the way, it was actually pretty flat), but I was highlighting the NCC had a steeper slope. They weren't budging on the conflict, so i wrote to Steve and had a chat and got his thoughts, which i provided to my builder. I explained to them that they were using an out dated document and were exposing themselves to liability claims if the path fails to perform. And "here by the way the guy that wrote it is telling you that the information is old and you should follow NCC". They promptly ripped up 12k worth of concreting "without prejudice" and replaced the lot. So i smile every time i see this guide handed out or referred to. That builder didnt even considder what i told them after that as i know new clinets 7 years later are still getting that document. I guess from a perspective where someone would not have otherwise considered the information previously, it does a good job in explaining the concepts, but it should be updated if its going to be relied on. Dark matter scientist, can breathe underwater, mind reader and can freeze matter just by willing it. Trust me, its in my sig. Re: Wall cracks, building footpath as per CSIRO BTF18 30Jan 07, 2023 4:01 pm groundzero The problem is that if the concrete dumps water at the far edge of the concrete then this can make the clay swell lifting the edge and tilt the concrete pavement back towards the house. Rainwater will then run towards the house causing water to seep into the clay next to your footing and create slab heave. There are a couple of alternatives, one is to have the concrete paving with inlet drains incorporated into it with the paving sloping towards the drains. This will require professional plumbing to install the drains before the paving is done and a concreter who does his job properly. The other alternative is to have a channel type spoon drain running parallel to the house along the outer edge of the concrete path and sloping towards an inlet drain that is connected to your stormwater system. Another option is not to have a concrete path and grade the ground level away from the house then place builders plastic over the sloping ground level. You can then put soil on top of the plastic and the plastic will direct moisture away from the house even when it is below the ground level and not visible. Don't use any material on top of the plastic that might puncture the plastic. Hi, For the builder's plastic option - the plastic traps a lot of moisture under it - would this be an issue on clay? Also, how would you ensure that the builder's plastic is tightly attached to the bricks? (so that water does not hit the brick wall and then travel between the bricks and plastic). Thanks Re: Wall cracks, building footpath as per CSIRO BTF18 31Jan 07, 2023 4:07 pm Can you have the agi pipe just travelling a decent distance away from the house so that any pooling water around the perimeter will not affect the house? Or should the agi pipe be connected to some sort of drain? This diagram is very helpful - thank you. Re: Wall cracks, building footpath as per CSIRO BTF18 32Jan 07, 2023 5:05 pm Do you mean without any paving or plastic ? Re: Wall cracks, building footpath as per CSIRO BTF18 33Jan 07, 2023 5:16 pm groundzero Do you mean without any paving or plastic ? Sorry, I wasn't clear. What I was asking is the following: What if we sloped the first 1m around he house with a fall of 50mm, and then put the builder's plastic as recommended. Would we still need an agi pipe on the perimeter of the plastic edge? (1m from the house). And if we do need an agi pipe, does it need to connect to a drain or can we just take it several metres away from the house and just let any water in it be absorbed by the soil? Hope that makes sense. Re: Wall cracks, building footpath as per CSIRO BTF18 34Jan 07, 2023 5:47 pm This is an option rather than a agi pipe but if you don't want to connected it to the storm water system then where ever it discharges (where the plastic sub surface channel ends) water will collect there and it could become very wet and soft so it should be away from any structures and not discharging into neighbouring properties. It will really depend on how your block slopes, block size, soil type etc. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Wall cracks, building footpath as per CSIRO BTF18 35Jan 07, 2023 5:55 pm If you want to use an agi pipe then it will have the same effect and create excessive water where ever it slopes to and ends. Normally they are connected to a pit which then transfer the water into the stormwater system which goes to a legal point of discharge. Re: Wall cracks, building footpath as per CSIRO BTF18 36Jan 07, 2023 6:05 pm groundzero This is an option rather than a agi pipe but if you don't want to connected it to the storm water system then where ever it discharges (where the plastic sub surface channel ends) water will collect there and it could become very wet and soft so it should be away from any structures and not discharging into neighbouring properties. It will really depend on how your block slopes, block size, soil type etc. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Yes, that's what we're concerned about - the water pooling at the end of the plastic, and the ground in that area becoming very soft/damp. We have H2 clay. We are on a couple of acres. The land slopes from the West to the East, so we get all of the surface water from our neighbour on the West. We get the most water on the West side of the house. On the other sides, the surface water has a nice fall away from the house. Installing an agi pipe all the way around the perimeter and then connecting it to the stormwater seems like a big (and expensive) task. We would like to avoid it if we can. But I can see how creating a fall for the first metre around the house (like the builder advises) is only likely to create a further problem. Re: Wall cracks, building footpath as per CSIRO BTF18 37Jan 07, 2023 6:07 pm groundzero If you want to use an agi pipe then it will have the same effect and create excessive water where ever it slopes to and ends. Normally they are connected to a pit which then transfer the water into the stormwater system which goes to a legal point of discharge. This is a good option to consider - thank you. Re: Wall cracks, building footpath as per CSIRO BTF18 38Jan 07, 2023 6:12 pm Do you know how deep the clays on the west side? Re: Wall cracks, building footpath as per CSIRO BTF18 39Jan 07, 2023 6:16 pm If you post photos that may help get a better idea of what is going on Re: Wall cracks, building footpath as per CSIRO BTF18 40Jan 07, 2023 6:16 pm groundzero Do you know how deep the clays on the west side? As in west suburbs of Melbourne? Deeper than you care to know lol Dark matter scientist, can breathe underwater, mind reader and can freeze matter just by willing it. Trust me, its in my sig. Hi all I am looking to run a water line under my concrete footpath which is directly next to my home, was seeing if this is possible without cutting the entire section… 0 20182 It sounds like you have a crack in your garage where the wall meets the ceiling, along the shadow line on the… 0 17198 Do I need to concern about this pattern of crack? Is this crack showing some signs of bigger problems? Thanks for any suggestions! 1 1914 |