Foundations....Before Fill?

[cheeryble]

Hi I've asked around this one before but now it's happening. I intend to build a house on a lot which requires 4ft to 6ft of fill around where the house will stand. I'm not sure if it was a rice field but it is lowish and flat and MAY have been rice field. Well obviously one doesn't want to dig through newly laid fill or build directly onto it for a long settlement time so thinking about that. Previously on TV asking about a lot which WAS a rice field I learned a little about pilings to transfer the load lower. So I believe the pilings may not be the type which are hammered in you simply dig or drill down then pour onto your rebar? So what would be a best sequence? And do the piles have feet or are they friction only? And does one have to test drill for harder ground level? BTW what would be a typical cost of pile work for a 1500sqft house on one or two floors? thanks a million

[bkkbill]

Depends where you are.

[David006]

first I ain't no civil engineer but we had a house built in Oz on a "floating" foundation in sandy rather soggy soil ... built like flat one side egg carton or upside down shallow box .Google it ...lots of info out there..

.maybe you may need this in combination with your piles..or pillars..don't see how pilings could have a "footing" as they would be duce difficult to "drive"??

good luck

[excaliber]

The most sensible answer to your question so far has been: "It depends on where you're building".

Some areas like Kalasin have mostly sandy soil "dinsai" while other areas are mostly clay beneath about one meter of soil.

In the latter, you will most often want conrete piling while in the sandy soil you may not need piles although the cost of piling compared to normal foundations isn't that different. If you want a better and stronger foundation/support system for the entire structure, then of course use piling @ five meters, give or take. If they rund into large boulders they will stop driving and cut the excess off at the top.

Another thing, You're building in Thailand and metric is used here and not Imperial units except for lumber sizes and a few other things like screws, nails, etc. There are free programs to download that will convert Imperial units to metric.

Don't expect an ARchitect or Engineer to understand your feet and inches and the builder won't appreciate wall distances in fractional terms, like 9' since the equivenlent in meters would end up with several decimal points that will only confuse the builder and not exactly cost effective for using materials properly, most specifically, steel.

You may want to check around your neighborhood to see if anyone has built on ricefield land and what type foundation they used. Then look around for cracks in beams and column where they meet the beams.

From your post, I'm assuming you want to bring the level up to the existing road. If the road is still dirt then you know sooner or later they'll make a better road with concrete or asphalt and the existing level will rise so you'll want to adjust for this unless you want all the water runoff to flow into your property. If you adjust the final level of your land in relationship to the existing road, add at least .5m for the finished floor of the house, or 1.00m is better.

Many will say it's better to fill now and wait through the rainy season to allow time for natural compaction then dig down again for the foundation footings. This is fine with piles but if you're building a normal foundation (without piles) then I sould build the foundation first then fill, then build your grade beams then fill again if need be.

and just to clear up a basic item. A structural engineer will design the structure for a residential house and not a civil engineer. Civil engineer's build bridges, high-rises, roads, etc. When you go to get approval for building you only need the signature of a licensed, Structural Engineer.

[cheeryble]

Thank you for your contributions.

Indeed I shall check the foundations for the largish house behind which was built on a lot of fill. It is 6ft higher than my base level (call it +0ft), and two feet higher than the dirt road out front of me (+4ft). What i'm considering is not to build a large and expensive front wall but make a moat/lake 64 metres long from on side to the other as a feature with maybe a mini wall or hedge just a foot or two high between it and the road. I would dig down a metre for the moat (-3ft) then have the water depth about 5 feet meaning the water would be 2 feet above the present ground level (+2ft). Than i would terrace up behind the water level another two feet for a garden level (+4ft). Then I would have the house on another two feet higher up bringing it to the level of the house behind (+6ft).... in fact would probably have stilts or semi stilts as well

This would seem to give a nice effect whilst requiring the least earth possible. The earth I dig for the moat/lake is probably quite good and if so could be topsoil on the fill earth behind.

Thankyou again and all advice welcome. For example what is the ball park cost of piles and grade beam work for a house, say per sq m?

[David006]

The most sensible answer to your question so far has been: "It depends on where you're building".

Some areas like Kalasin have mostly sandy soil "dinsai" while other areas are mostly clay beneath about one meter of soil.

In the latter, you will most often want conrete piling while in the sandy soil you may not need piles although the cost of piling compared to normal foundations isn't that different. If you want a better and stronger foundation/support system for the entire structure, then of course use piling @ five meters, give or take. If they rund into large boulders they will stop driving and cut the excess off at the top.

Another thing, You're building in Thailand and metric is used here and not Imperial units except for lumber sizes and a few other things like screws, nails, etc. There are free programs to download that will convert Imperial units to metric.

Don't expect an ARchitect or Engineer to understand your feet and inches and the builder won't appreciate wall distances in fractional terms, like 9' since the equivenlent in meters would end up with several decimal points that will only confuse the builder and not exactly cost effective for using materials properly, most specifically, steel.

You may want to check around your neighborhood to see if anyone has built on ricefield land and what type foundation they used. Then look around for cracks in beams and column where they meet the beams.

From your post, I'm assuming you want to bring the level up to the existing road. If the road is still dirt then you know sooner or later they'll make a better road with concrete or asphalt and the existing level will rise so you'll want to adjust for this unless you want all the water runoff to flow into your property. If you adjust the final level of your land in relationship to the existing road, add at least .5m for the finished floor of the house, or 1.00m is better.

Many will say it's better to fill now and wait through the rainy season to allow time for natural compaction then dig down again for the foundation footings. This is fine with piles but if you're building a normal foundation (without piles) then I sould build the foundation first then fill, then build your grade beams then fill again if need be.

and just to clear up a basic item. A structural engineer will design the structure for a residential house and not a civil engineer. Civil engineer's build bridges, high-rises, roads, etc. When you go to get approval for building you only need the signature of a licensed, Structural Engineer.

hmmmm...subtle flaming hugh..

sounds like a pole home would answer rather than on a slab ....maybe the OP should hire an engineer/architect to survey and advise on site prior to designing the house? ..one that has built houses or high rises/bridges or roads maybe?? Do people actually get engineers to sign off on domestic structures in LOS..maybe in the cities?

There is a gas station near us that is being built on about 3-5m high fill supported by concrete planks and poles on the perimeter...half of 'em collapsed in the rains but the building continues regardless....TIT!

In Vancouver/Richmond where they build on the river delta plain they put about a 5 meter high fill to preload and then wait a year or so before building ...one Thai builder here told me he does the same...

Then again the wifey told me of a development in the north that "sunk" and all the houses are cracking up..

[harrry]

Thank you for your contributions.

Indeed I shall check the foundations for the largish house behind which was built on a lot of fill. It is 6ft higher than my base level (call it +0ft), and two feet higher than the dirt road out front of me (+4ft). What i'm considering is not to build a large and expensive front wall but make a moat/lake 64 metres long from on side to the other as a feature with maybe a mini wall or hedge just a foot or two high between it and the road. I would dig down a metre for the moat (-3ft) then have the water depth about 5 feet meaning the water would be 2 feet above the present ground level (+2ft). Than i would terrace up behind the water level another two feet for a garden level (+4ft). Then I would have the house on another two feet higher up bringing it to the level of the house behind (+6ft).... in fact would probably have stilts or semi stilts as well

This would seem to give a nice effect whilst requiring the least earth possible. The earth I dig for the moat/lake is probably quite good and if so could be topsoil on the fill earth behind.

Thankyou again and all advice welcome. For example what is the ball park cost of piles and grade beam work for a house, say per sq m?

I suggest you do not bother checking the other building. What they have done or not done will not give you any guarantees. When they build here they just go round and fill in the cracks as they occur in housing estates. If you want to be sure plan well and stick to it even if the people say it is wasting and not needed. On the other hand buildings lean and sag here but not many fall down.

[David006]

Thank you for your contributions.

Indeed I shall check the foundations for the largish house behind which was built on a lot of fill. It is 6ft higher than my base level (call it +0ft), and two feet higher than the dirt road out front of me (+4ft). What i'm considering is not to build a large and expensive front wall but make a moat/lake 64 metres long from on side to the other as a feature with maybe a mini wall or hedge just a foot or two high between it and the road. I would dig down a metre for the moat (-3ft) then have the water depth about 5 feet meaning the water would be 2 feet above the present ground level (+2ft). Than i would terrace up behind the water level another two feet for a garden level (+4ft). Then I would have the house on another two feet higher up bringing it to the level of the house behind (+6ft).... in fact would probably have stilts or semi stilts as well

This would seem to give a nice effect whilst requiring the least earth possible. The earth I dig for the moat/lake is probably quite good and if so could be topsoil on the fill earth behind.

Thankyou again and all advice welcome. For example what is the ball park cost of piles and grade beam work for a house, say per sq m?

I suggest you do not bother checking the other building. What they have done or not done will not give you any guarantees. When they build here they just go round and fill in the cracks as they occur in housing estates. If you want to be sure plan well and stick to it even if the people say it is wasting and not needed. On the other hand buildings lean and sag here but not many fall down.

:clap2: :clap2:

[cheeryble]

You may be right about not copying any other house excalibur. though somehow I doubt they'd fill the cracks in that one so may be something to learn as it's built on 6 foot of fill.

....So normally for piles it's not just deep excavations they actually bring in the truck with the pile driver tower, seems a lot for a house? How much a day? How many days for a modest house 1500sqft? What would be a typical pile size?

thanks

[trogers]

what would be a typical cost of pile work for a 1500sqft house on one or two floors?

If the house is 2-storey, I will do a soil test and get a proper structural engineer to design the foundation. Piles supporting structures more than a single floor have to bear double or more loads per pile and failure can cost lives.

[excaliber]

You may be right about not copying any other house excalibur. though somehow I doubt they'd fill the cracks in that one so may be something to learn as it's built on 6 foot of fill.

....So normally for piles it's not just deep excavations they actually bring in the truck with the pile driver tower, seems a lot for a house? How much a day? How many days for a modest house 1500sqft? What would be a typical pile size?

thanks

I don't recall saying not to copy any other house. If you check around to get an 'idea' of what type foundations were used it will help in deciding what you want for your house. Example: If you find houses with normal foundations and large cracks in walls, etc., as compared to houses built with piles and without cracks then you have found the answer unless of course all the cracks have been filled. Ask questions?

For prices you may want to click on one of the google sponsors here "foundation piles", a Thai company. They can tell you what you want to know, maybe.... typical pile size is .30m x .30m x 3m, 4m, 5m, etc.

If you need professional help, PM to me the details and I will pass them on to the Structural Engineer for evaluation and fees.

Edited July 9, 2011 by excaliber

[JAS21]

I have just watched piling in our Village Green where they are building a small single story office. They dug six piles, each was dug 13Mtrs deep and the steel was 10M long and hung on the piling m/c whilst the concrete was poured.

The piling crew, three guys, were quite quick even if a bit rough with the equipment.

They got to clay after about 2Mtr. It actually took two days to do the six piles...longest time was waiting for the cement to arrive from CPAC, sometimes they waited 3 hours! Dug a pile and then ordered the cement!

On average it took around one hour to dig each pile. They used six lengths of pipe/tube, each about 2Mtrs long and I guess dug a little lower than the bottom of the last pipe/tube.

Interesting to watch................I did ask the guy about a two story house and I think he said 13M was about the norm for that around here. Of course there is the large piller to go on the top of the pile. And on top of that they will lay pre cast concrete slaps..I believe.

It can't be that much more expensive to go down a few extra metres. Anyway you have had plenty advice about ensuring that the designer/builder knows what he is doing.

I have a few photos and a video.....if you have never seen it done. Video is too big to post though.

Don't skimp on the piling!!! Where I live, the last few houses, and ours was one. The company added on external kitchen and Maids Room....idiot designer decided not to pile as deep as the house. Resulting in after a few months the extra bit dropped and they had to repile, dig under and put horizontal concrete 'posts' to support. Made a mess of the garden! but now nothing is moving and that is 4 years later.

[cheeryble]

Thankyou for the replies and JAS21 I sent you a private message with my email address.

Wow 13metres seems a lot for a small single floor office. O f course I wiill require a lot more than 6 piles.. And it seems like piles are not all hammered in they bore a hole with a spiral tool on the end of screw-togetherable pipe lengths then concrete in?

Wonder if anyone knows a typical depth in the valley floor just north of Chiangmai....

[bbradsby]

Just saw this thread, and not to be grumpy.... but please read the related threads via keyword search, then revive the most apropos one to ask any new questions/clarifications. All these questions have been answered, pretty sure, tho working from memory. If we keep the accumulated information unscattered, it benefits everyone who comes here via easy access.

I'll just say here that every site - even every individual driven pile - can go to a different depth before gaining the proper resistance. I for one would not use poured piers unless theyre bearing on solid stratum... and you have to be an architect or engineer to recognize it unless its solid rock. Even then. Dont scrimp on your house design & foundation work any more than youd scrimp on a heart surgeon. A lot is riding on it

All the best,