We recently purchased 250 talong wah of rice land and put fill dirt to raise it 1.5 meters. There is only rice land adjacent. so the land is like an island. Has anyone built on land like this? My first question is whether we actually need a wall to support the land before we build. We would prefer not to build a wall due to cost, but want the land to be stable enough to build on. The house will be 13 feet from the nearest edge and over 20 feet on the other sides. There is also a stretch of raised 15 foot wide access driveway. We will not surface the road until the construction is complete. If anyone has actualy built on raised filled land like this I would appreciate any information on what we should consider before building. Thanks

Hi you can expect the fill to settle and compact significantly for at least a year or two. I recently built a workshop on paddy land and had it built on piers supported by pads buried about 1.5m below the paddy level and extending 1m above, and did the fill after. Building 'slab on fill' style is asking for trouble IMO and I wouldn't surface the access road with anything but gravel for at least a year either.

We built on land about 30cm above surrounding rice paddy. Footings dug into existing land level, raised house about 1m above this level. Then added fill extending about 1 - 2 metres away from the house, then sloping down to the existing land level. So most of our nearly 3 rai garden / orchard was not raised.

Be aware that living right by paddy leaves you open to lots of frogs, then snakes, and vast amounts of mozzies, along with possible fireworks to scare the birds away, noisy harvesters, and the burning of fields. With that I'd be throwing up a 15ft wall. It's very picturesque 'n all, but can get old fast.

As Cloudhopper and ME Smith said, the important thing is to dig the footings well into the old rice paddy level and elevate the house a meter or more above the yard level. That way you are not dependent on the quality of the fill dirt and the house will be high and could even have a crawl space underneath to simplify repairs to plumbing and electrical.

Build a retianing wall - it will help to keep unwanted wildlife out and also stop erosion casused by the run off water during the rainy season.

Build a retianing wall - it will help to keep unwanted wildlife out and also stop erosion casused by the run off water during the rainy season.

That would be a great feature alright but prohibitively expensive I bet. What do you reckon a 1.5m retaining wall above flooded paddy land would cost a running meter? A cheaper alternative to reduce fill-slope erosion would be to plant some vitiver grass (ya fek).

Impossible to answer with any degree of certainty without some in depth knowledge of the underlying soil, groundwater level, pore pressure dissipation, and settlement data since the fill was placed.

When do you expect to begin construction - can you want a year or so for pore pressures to dissipate and settlement to flatten out

What type of foundation is planned

How big a house and how many stories. Presumably concrete beams and block infill.

Are you willing to drill a borehole for geotechnical data - this may serve double duty as a water well if groundwater conditions allow

Are you willing to drive piles and make this all irrelevant. The cost is not as high as you might think

Are you planning a swimming pool

So many questions that could have been avoided with input from a geotechnical engineer, and cheap insurance at local engineering rates. With a small house, a single borehole will answer a lot of questions

Lots of people wing it, however I would not rely on Somchai's past experience in foundation work unless the risk in getting it wrong did not matter to me.

Thanks to you all for your input so far. I should have mentioned that the adjacent "rice land" is not under cultivation as it is up for sale, so the only water accumulation to attract frogs, mosquitoes etc. would be rain water. We definitely plan on building on piers down to the "original " land.

same story raised pad and then around about five metres before the boundary of the land area start sloping the dirt back to the level of the paddy no probs except the native wild life wants to sliver around just have a good whacking stick

Just an Island, like the beautiful house in Bali! They got much more taste than the average mindless thai architekt.

assuming you are building with concrete not wood-the footings for the building need to be on virgin(undisturbed for some 20 years) soil.

that translates about 1.5 - 2 m below the paddie

it would have been easier to put them in before filling but it is all the same no big deal - putting the house safely on fill will be far more expensive then digging a little deeper

Saw this on DIY. Anyway... an alternative to a "wall" is to put in a hedge to prevent soil erosion and basically have a nice "wall" after one year. You can find the young sprouts at the nursury for (I forget) not too expensive and in 1 year you will have a very nice perimeter over 1m high. The caveate is you will need to maintain - like cut and trim.

As for your land fill... it doesn't matter how much fill you put in or how long you wait for it to set, you probably need to set footings well below the fill for any permanent structure.

The land I am building on is corn field and not rice. By the time I build it will have set through 3 rainy seasons. I had the topsoil dug out down about 1/2 meter (to the large rocks) and filled back in to about 1/2 meter above the surrounding soil. The fill was a mix of clay and rock which is naturally occurring (called 'HIN' locally in Issan) and gets hard as rock after the settling period.

I have been told that it is fine to build on this.

Iwould definately leave it for atleast 2 years as we had a dam filled and in one year it has sunk by 300 mm - 400 mm and i would not risk building on this till another year atleast and / or do what everyone else says and put piers onbnexisting land level with concrete footings and have an elevated house