Soil For Land Fill

[JimmyGreaves]

I am looking to fill some land in Hua-Hin / Cha am area, 1/2 rai.

Can someone give me some pointers of what I need to look out for when getting this job done and a rough idea of cost. The land is to be used to build a small bungalow.

Cheers

[Morden]

I don't know your area but from my own experience in Korat:

You pay by the truck load. We paid 130 baht per small truck for the heavy stuff to go beneath the buildings. It would have been a tad cheaper but there was none very close to the land on the day. When we bought good quality topsoil it cost 280 baht per big truck. I forget the exact metric volumes. It's important to get the type that you need for each part of the land and don't spread the heavy stuff all over the garden.

We had no problems but do agree the price per load and ask for the cloakroom tickets before the first load arrives. You give one to each driver as he drops his load and count the counterfoils when the jobs done. A tractor will level as the fill arrives and there should be no extra cost for that.

We decided to fill first for the buildings and make sure that it was compacted. The topsoil was left until the house was nearly finished so that we could make the right visual judgements about gradients to the boundaries and the lie of the garden.

I think that another member asked about this same thing recently. Do a search and you should find out more.

[N&M]

Bangkok is 1400b for 6 wheel truck carrying 8 cubic meters for dirt and 2080 per truck for sand.

[chownah]

In building the house, assuming that it will be the standard post and beam concrete construction, it is best for the foundations for the posts to be built down in the original undisturbed earth.

[BKK90210]

No clay, black soil, or any soils with good amount of organic debris.

Sand is best for foundation, only if you can ensure the proper compaction of at least 6-lift.

The meaning of 6-lift.....have a compactor or heavy tractor runs over back and forth for every 6" vertical of fill dirt/sand. 4"-lift would even be better, but for your small house 6"-lift should be sufficient enough. This is to ensure the foundation has a fairly decent proper ground compaction, hence avoiding many future settlement problems which will occur in a few yrs time.

[BKK90210]

"JUST IGNORE THE PREVIOUS POST ABOVE, IT WASN'T COMPLETE"...but don't know how to delete it

Below is the completed one

No clay, black soil, or any soils with good amount of organic debris.

Gravels is best (about 3/4" minus, which mean 3/4" dia. is the largest with other smaller dia. mixed in)...but it is more expensive than sand

Sand is the second best for foundation, only if you can ensure the proper compaction of at least 6-lift.

The meaning of 6-lift.....have a compactor or heavy tractor runs over back and forth for every 6" vertical of fill dirt/sand. 4"-lift would even be better, but for your small house 6"-lift to 12"-lift should be sufficient enough. This is to ensure the foundation has a fairly decent proper ground compaction, hence avoiding many future settlement problems which will occur in a few yrs time.

Just remember the bigger and heavier equipment - the higher lift you can have and the better material you can use.

[Morden]

In building the house, assuming that it will be the standard post and beam concrete construction, it is best for the foundations for the posts to be built down in the original undisturbed earth.

That's very good advice. However much compacting is done there's always a possibility of some movement later in raised ground. A visual check of the holes would be a good idea - and remember the leaf in the first one and the monks for good luck!

[chownah]

Getting good dirt and getting it properly compacted can be a problem. Using 6 inch lifts as described will be almost impossible if you buy the dirt and expect the tractor that comes with it for free to spread the dirt and compact in this fashion...the usual method is to dump in piles and then knock off the high spots. Good luck......that's why in post #4 above I recommended that the foundations for the posts be deep enough to be constructed in the original undisturbed soil. If you do this and then follow usual construction procedures then settling problems (if any) will be minor and will not cause problems with the major support members......this of course assumes that you are building the standard post and beam construction and that your fill will not be really deep.

[JimmyGreaves]

Thanks for the information. It's strange that all over Hua-Hin most of the land for sale has had soil/sand dumped on top 1 metre high. Does this still make life easy to still get down to the original land level for the foundations in a post and beam construction?

[N&M]

I would think the main reason for adding soil to that level and I have seen it many times, is that the area may flood and they want to be above it. Have you been in the area long and does it flood ?

Also most of these blocks seem to be left for a long time and natural settlement occurs over that time. As for getting down to the hard level, you gotta dig.

Another method is to put in Pilings that will/should stop any settlement. Pilings can go down a long way depending on the area.

We just put in 28 at 23 meters each and they initially went in the first 10 meters or so like butter, or knife into butter, or (should I say it....nah, Khutan might be a little sensitive today again and ban me again).... they are also not cheap, but its all relative, i would rather spend the cash and not have settlement problems later. Cracks in your new house and your steps ending up 6 inches below where they should be really suck.

[chownah]

Thanks for the information. It's strange that all over Hua-Hin most of the land for sale has had soil/sand dumped on top 1 metre high. Does this still make life easy to still get down to the original land level for the foundations in a post and beam construction?

I have seen some gov't published books that show complete drawings for various styles and sizes of houses and shop houses. I was interested in the designs for two story post and beam houses so that is what I will talk about. I know that you are building something smaller so this would surely be adequate for you and perhaps overbuilt.

First: The plans alway showed two types of foundations for the posts....one type using pilings and one using a concrete pad (called a spread footing in the US). As N&M pointed out pilings if done properly will surely eliminate any settlement problems. To decide which to use I would either check out what the neighbors have or rely on a local contractor's judgement....or the property manager if you are in a big development.

Second: If you decide (or someone else decides for you) to go with pilings then whoever is in charge of designing this part of the house or doing the work will supply the details and if done properly then there will be no settlement problems....of course except for the settlement in the size of your money pile. If you go with the concrete pad....then what I saw in the gov't plans book is that the minimum depth from the ground level when done down to the bottom of the concrete pad that serves as the foundation for the posts is 120 centimetres.....This is very compatible with a 1 metre fill allowing the foundation to be constructed in the original undisturbed earth. Let me point out that it is best if the top of the concrete pad is at or below the original ground level. If the bottom of the pad is just set at the original level with poorly compacted earth around the sides then over a long period of time you might get some settlement...might not...better to dig 25 centimetres more...or even 40 centimetres more and be sure, in my opinion. On top of this pad is then built a stub column which is stronger (larger cross section and more steel) than the posts in the house and on top of these stub columns will be built a beam (called a grade beam in the US)...actually several beams all around and connecting all the stub columns. These grade beams will support the floor and the posts that hold up the upper floors and the roof. The grade beams are built hefty enough so that they would be strong enough to support everything even if the soil underneath them provides no support.

I'll stop here. I'm a firm believer in getting the foundation right. If you feel unable to decide between pilings and spread footing then get some expert advise about the actual conditions where you will be building. It might be good to do this before you put in the fill just because then it will be easier to examing the existing earth. Try to get good compaction regardless since it never hurts and who knows what features you might want to build later. As N&M pointed out, bringing in fill and getting the best compaction you can AND then waiting a year or more for natural settlement is great but usually waiting is not an option.