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What comes first, the pond or the posts ?


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Posted

I have never built a house on a pond before....looking for some advice re what comes first or how the posts are constructed when the buildings edge, mostly the wrap around balconies, will overhang the water.

I would presume putting in the posts first and then excavating around them, but just wondering if any other techniques.

The ground is solid underneath, but high water table. Have been told and have not seen myself, that nobody in the area sinks 'piles'....if not, how to get the foundations down deep enough below the bottom depth of the pond...say 3 metres, as i think with the high water table, if excavation down to form foundations and posts, it will be flooded in no time and unable to work in it.

Posted

Precast concrete piles are not equal to concrete columns. There is no steel reinforcement along the length of a pile, just at the head and toe. Piles will snap or fracture when subjected to lateral forces. When driven into the earth, the surrounding soil provides the lateral bracing to the piles.

You will have to pile the foundation and construct the pile caps and tie beams just below the bottom of the intended pond, and then construct the columns up for the house. If groundwater level is high, you will need to use sheetpiles and employ dewatering like those used in basement construction.

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Posted

What are 'sheetpiles"....steel sheets to hold the water back ?

If so, not practical here as too large area and too expensive for a house.

If I decided to go with piles, I was thinking to get poured rather than hammered, then it shall be reinforced.

But still looking for other avenues.

Posted

What are 'sheetpiles"....steel sheets to hold the water back ?

If so, not practical here as too large area and too expensive for a house.

If I decided to go with piles, I was thinking to get poured rather than hammered, then it shall be reinforced.

But still looking for other avenues.

Bored piles need heavy machinery which contractors may not be willing to do for a single house unless you are located near a major city.

But the question is, why do you need such a deep pond? The appearance of a pond is the same whether it is only 1m deep or 3m deep.

Posted (edited)

We have built brick & tile over a ~6M deep, ~800sqm pond before - in that case we definitely dig the pond out first, as there just no other way to get the footings right.

At 3M deep I would still do the same though I guess, dig the pond pond first, hammer 10M long piles all the way down to 1-1.5M below the pond floor, then build footings on top of them. In our case, 3 of the center posts used 3Mx3M footings on top of 4 piles each. You should speak to an engineer who knows the water table and land composition in your area to work it out.

Edited by IMHO
Posted

What are 'sheetpiles"....steel sheets to hold the water back ?

If so, not practical here as too large area and too expensive for a house.

If I decided to go with piles, I was thinking to get poured rather than hammered, then it shall be reinforced.

But still looking for other avenues.

Bored piles need heavy machinery which contractors may not be willing to do for a single house unless you are located near a major city.

But the question is, why do you need such a deep pond? The appearance of a pond is the same whether it is only 1m deep or 3m deep.

Not really, deeper pond stays cleaner, temp cooler, algae control and much better natural bio diversity.

As for poured piles, they have mini manual operated machines here that can be moved into hard to get to areas and they will and do single house jobs, seen it many times.

In fact saw such setup just few days ago, stopped got photo which I will post here later and got there phone number for a price...but it is basically a tripod with the rig set up under it and a gernerator.....so could easily use that kind of rig...unless ridiculously expensive.

Posted

We have built brick & tile over a ~6M deep, ~800sqm pond before - in that case we definitely dig the pond out first, as there just no other way to get the footings right.

At 3M deep I would still do the same though I guess, dig the pond pond first, hammer 10M long piles all the way down to 1-1.5M below the pond floor, then build footings on top of them. In our case, 3 of the center posts used 3Mx3M footings on top of 4 piles each. You should speak to an engineer who knows the water table and land composition in your area to work it out.

How did you keep the tide back while doing the footings and posts ?

I know the water table here, we have a small natural pond on the boundary that has water in it all year, it rises and falls with wet and dry season, but only by about half a metre.....we live in a river bed valley with mountains around, the river is 100m away from our block...does not flood before anyone worries about that issue

  • Like 1
Posted (edited)

We have built brick & tile over a ~6M deep, ~800sqm pond before - in that case we definitely dig the pond out first, as there just no other way to get the footings right.

At 3M deep I would still do the same though I guess, dig the pond pond first, hammer 10M long piles all the way down to 1-1.5M below the pond floor, then build footings on top of them. In our case, 3 of the center posts used 3Mx3M footings on top of 4 piles each. You should speak to an engineer who knows the water table and land composition in your area to work it out.

How did you keep the tide back while doing the footings and posts ?

I know the water table here, we have a small natural pond on the boundary that has water in it all year, it rises and falls with wet and dry season, but only by about half a metre.....we live in a river bed valley with mountains around, the river is 100m away from our block...does not flood before anyone worries about that issue

The footings didn't get down to the water table, so pumps did the job. if your footing depth is deeper than the water table, you will need to box around the beams and use a waterproof barrier when pouring the footings/posts.

Again, you should not be making any decisions in this yourself - you should be engaging an engineer.

Edited by IMHO

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