As in west suburbs of Melbourne? Deeper than you care to know lol
HaHa
Browse Forums Building Standards; Getting It Right! Re: Wall cracks, building footpath as per CSIRO BTF18 54Jan 08, 2023 5:09 pm It is to take the majority of the water and direct it North away from the house before the brick wall blocks that area off. Then the cut off drain at the rear of the west of the house catches less and discharges less to the south which would make the ground there less boggy or not boggy. A spoon drain will not catch the subsurface water. You can test this by digging a hole at the west of your house and seeing if it is wet and starts to collect water do this during a wet period. Remember to go down to at least the start of the natural clay.If there isn't any then you can deal with the surface water only. Is the animal paddock yours or your neighbours? Re: Wall cracks, building footpath as per CSIRO BTF18 55Jan 08, 2023 5:50 pm groundzero It is to take the majority of the water and direct it North away from the house before the brick wall blocks that area off. Then the cut off drain at the rear of the west of the house catches less and discharges less to the south which would make the ground there less boggy or not boggy. A spoon drain will not catch the subsurface water. You can test this by digging a hole at the west of your house and seeing if it is wet and starts to collect water do this during a wet period. Remember to go down to at least the start of the natural clay.If there isn't any then you can deal with the surface water only. Is the animal paddock yours or your neighbours? That makes sense - thank you. The animal paddock is ours. It's about 30m wide, so that's roughly the distance between the neighbour's fenceline and our house. I will carry out the test you recommended when it rains. I think we are getting surface and subsurface water from our neighbour. We literally have a swimming pool in our animal paddock when it rains. The ground takes forever to dry. Is a cutoff drain a better option than a spoon drain (along the neighbour's fence line) then? The animal paddock is all clay so we shouldn't have to dig it that deep, right? Re: Wall cracks, building footpath as per CSIRO BTF18 56Jan 08, 2023 6:03 pm I cut off drain near your neighbours fence line would be better than a spoon drain as a cut off drain can do both surface and subsurface. You need to see the soil profile, is it fill over natural clay of is it natural topsoil over natural clay? Your neighbour may be discharging stormwater onto the ground or there may be a overflowing pool/dam.Finding the source of the excess water would be a good idea and maybe the best option and not cost you anything depending on how you get on with your neighbour. If that doesn't work then a cut off drain near the fence line may be the best option especially if you can't hook up to your stormwater system. Dig out the soil profile then you can work out how deep you need to go with the cut off drain if you can't find the source. Re: Wall cracks, building footpath as per CSIRO BTF18 57Jan 08, 2023 10:40 pm Interesting discussion. To begin with, I would never put my footings into reactive clay. Why not to simply replace clay with 30 cm of compacted sand or low aggregate gravel over geotextile and with proper perimeter agg drainage. You need to replace your building envelope + 1 meter in each direction. Obviously, you would need to prepare your building envelope slightly sloping towards the drainage when excavating. Then concrete apron will be just an optional/good to have thing and you would have the best possible protection and foundation for your footings. As advanced option I would be also looking into something like EZ-Drain in order to save costs on gravel. https://www.ndspro.com/products/drainag ... drain.html Re: Wall cracks, building footpath as per CSIRO BTF18 58Jan 09, 2023 7:57 pm This is an existing house so Lisa06 has to deal with an existing drainage issue and not a new construction situation. 30cm isn't a great deal to reduce the reactivity profile eg West of Melbourne climate category 4 has potential ground movement down to 2.4m.But the less reactive soil the better and what you say about perimeter pavement, grading the soil away from the slab and agg pipe would probably solve must drainage situations and slab heave. Conventional raft slabs often have edge beams down to 300-400mm below ground level in reactive soils but this is different with waffle slabs. Re: Wall cracks, building footpath as per CSIRO BTF18 59Jan 10, 2023 7:41 pm groundzero I cut off drain near your neighbours fence line would be better than a spoon drain as a cut off drain can do both surface and subsurface. You need to see the soil profile, is it fill over natural clay of is it natural topsoil over natural clay? Your neighbour may be discharging stormwater onto the ground or there may be a overflowing pool/dam.Finding the source of the excess water would be a good idea and maybe the best option and not cost you anything depending on how you get on with your neighbour. If that doesn't work then a cut off drain near the fence line may be the best option especially if you can't hook up to your stormwater system. Dig out the soil profile then you can work out how deep you need to go with the cut off drain if you can't find the source. I agree that a cutoff drain would be better than a spoon drain near our neighbour’s fence line. What is the difference between fill versus natural topsoil over natural clay? A neighbour told us that when the area was just vacant land, they added piles of topsoil over it, so my guess is that it’s fill over natural clay. How can we tell? Our neighbour doesn’t appear to be discharging stormwater onto the ground. He has water tanks close to our fence line, and his overflow seems to go somewhere underground (not sure where though). He also doesn’t have an overflowing dam. When it rains a lot here, there is a lot of surface water. Even our neighbour’s land holds various pools of water. He has built his land up higher than ours though, so any surface water falls into our property. When you say “dig out the soil profile” - what exactly do you mean? I’m happy to dig, but I’m not sure what I’m looking for. I guess it would be obvious when I hit clay. Re: Wall cracks, building footpath as per CSIRO BTF18 60Jan 10, 2023 7:44 pm alexp79 Interesting discussion. To begin with, I would never put my footings into reactive clay. Why not to simply replace clay with 30 cm of compacted sand or low aggregate gravel over geotextile and with proper perimeter agg drainage. You need to replace your building envelope + 1 meter in each direction. Obviously, you would need to prepare your building envelope slightly sloping towards the drainage when excavating. Then concrete apron will be just an optional/good to have thing and you would have the best possible protection and foundation for your footings. As advanced option I would be also looking into something like EZ-Drain in order to save costs on gravel. https://www.ndspro.com/products/drainag ... drain.html If we had built this house, we would have done things very differently. But we are the second owners, and we're just trying to do our best with a bad situation. 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