Raising land level to avoid flooding. Advice please

[ubonr1971]

We are thinking of buying 2 rai of land that borders a river at the end of the block. You can see the photo attached. 

 

I think the land is valuable because theres public road around the entire boundary i.e. no neighbours right on proposed fence that one might have when living in a gated community, for example. 

 

There are 2 big houses either side that basically can look into our block from their second stories. But I suppose we can plant blockout trees etc. I think the proposed sites of the 2 houses are in correct position would you agree?

 

The main issue with the land is that it can flood. A few years ago there was really heavy rain and apparently a government department opened up a water channel or whatever and there was huge flooding. I remember this whole area on the main road was flooded bc I could not drive my car on the main road that is in the attached photo below. The water was up to the top of the wheel of a car I think. During that time the river was really high but I couldn't actually go and see it as I didnt want to drive my car down that road with the high water levels. 

 

Therefore I think the 2 options are:

1. Both proposed houses have to be on stilts ie raised by a meter or 2

or

2. Add soil and raise the land in only the areas where the houses are. If the flooding event happens again then only the lower areas will be flooded. 

 

What about drainage? Should we be putting slotted ag pipe all the way around the entire boundary on the inside of the proposed concrete wall that we intend to build. The run off could be at the river end. A pipe going down to the river. Would this be advisable to you think?

 

Its hard to decide if we should make an offer and buy this land. Any opinions are appreciated

 

 

[DavisH]

How much soil would you plan to add? It's quite expensive to do that. My wife put 100K baht of soil onto 2 rai of land,. The increase in land level was quite small. We still need to add a lot more if we plan to put a house on it (the brother-in-law lieves next door), so we need it up to about that height. It could cost several hundred thouand to increase the level significantly. I would recommend a house on stilts, or a house with a significantly raised bottom floor (so several steps up into the house....and a raised parking area. If you have a pool or a pond, that dug soil could be used to raise the land also. I dont think the land flooding is a big problem; you just dont want water in your house or vehicles. 

[Elkski]

What if it floods again?  You may be up on stilts but no coming and going if it's tire deep on the roads.  It seems like tuy gave drawn that one neighbors house right 9nbthe property line.  Perhaps build a pool pump house on your property linevto give you privacy at the pool.   I woykd want to invest in an area that never floods.  V

[Sheryl]

Stilts. (Or don't but at all which would be best advice. Note that Flooding on the whole keeps getting worse here). 

 

And see if there is scope for creating some sloping  channels for water run off a2ay ftom the hoysr.

 

Do not assume lack of neighbors/privacy  makes the land valuable. Often the reverse is true in Thailand. Thais do not like to live far from other houses...and will consider far to be anything not in clear earshot.

[ubonr1971]

1 minute ago, Sheryl said:

Stilts.

 

And see if thetlre is svope for creating some sloping  channels for water run off aeay ftom the hoysr.

 

Do not assume lack of neighbors/privacy  makes the land valuable. Often the reverse is true in Thailand. Thais do not like llto live far from other houses...and will consider far to be anything not in clear earshot.

Your last sentence is very true. We have been looking for several years. My wife dislikes land that is too remote due to security issues. Neighbours can be good for security or bad of course. As its not a western country I think its better to have neighbours around for safety issues. The small soi around the entire boundary is good for us I think. Its a big selling feature to be honest. 

 

When you say sloping channels for run off... does it mean we should have drainage pipes leading to outside the walls?

[CharlieKo]

Buying Land in an area you know floods, is a bad idea. Once flooded how do you get to and from your house? What about the pool needing to be drained and refilled after the flooding subsides? You would need to build a raised parking area or you might have to buy a new car after each flood. Don't buy an EV! Being so close to the river is drainage from the land even relevant. The water will only go down as the river level drops. 

Good Luck but I think you could live to regret it. Find a better piece of Land. 

[Cake Monster]

Land that is prone to flooding is a nightmare.

Not only do you have to raise the Land level, or live on a stilted platform structure, you have the issue of access and travel Etc when the surrounding area floods.

Find something else

There are many good plots of land for sale, that are not prone to floods.

 

[Hummin]

As a few said, do not buy land that is flooding. Anyway if the price of the land and the location is right for you and your wife, then go ahead, and study drainage for the land and build with a 100 year flooding scenario in back of your mind. 
 

It is just the matter of how much you are willing to pay to secure it. 
 

Price for two rai and what title do the land have? If not chanote, why even bother? 

[realfunster]

42 minutes ago, CharlieKo said:

 Once flooded how do you get to and from your house?

Easy access via the river by boat. Drop off at the 1st floor private 'sky' dock, purpose built for such occasions.

 

Just kidding.

 

Back to the OP :

I live in an area of central Bangkok that was prone to flooding, neighbours tell me it was chest deep here back in the mid-90s and I have electrical sockets that are fitted half-way up the wall, which gives the game away ! However, to the best of my knowledge no floods at all in the 25+ years since then and definitely not in the 15 years I have been here. 

 

Yours is an interesting case, I can see the attraction of a nice property overlooking a river but being near a river comes with risks. 

 

On the basis everyone else has told you to stop considering this, let me offer an alternative view. As your map shows, many others have built there- so why not you ?

 

With numerous houses and 2 main roads in the direct vicinity, you would expect that the 'authorities' will have a reasonable motivation to keep the area dry, if at all possible. Try to establish the risks - what's the historic and ongoing flood situation - was the previous flood just a f-up by the local water management team ? How often have there been floods on the property over the past twenty years ? What's the general state and condition of neighbouring land and properties ?  Either way, it would obviously be prudent to build in some flood-proofing into your house/land designs (any design clues from neighbouring properties?) and if it's a once a decade or more thing then you can evaluate whether you see not being able to access your property for a few days/weeks once every 10 years and some clean-up/repair costs as a price worth paying, assuming the main property and belongings of value are safe and sound above the water line.

 

[Hummin]

Another thing to consider, are you on a outer bend of the river? And is the river a natural walled river or have they done any reinforcment to it? 
 

If you are on a outer bend, the river will continue to digg in to your borders and finely cave in little by little. If it is straight, them it is not that crucial depending on if its a wide section of the river or a more narrow one. 

[richard_smith237]

2 minutes ago, Hummin said:

Another thing to consider, are you on a inner bend of the river? And is the river a natural walled river or have they done any reinforcment to it? 
 

If you are on a inner bend, the river will continue to digg in to your borders and finely cave in little by little. If it is straight, them it is not that crucial depending on if its a wide section of the river or a more narrow one. 

It is the ‘outer’ bend of the river where the erosion occurs. 

 

 

[Hummin]

16 minutes ago, richard_smith237 said:

It is the ‘outer’ bend of the river where the erosion occurs. 

 

 

I mixed it up, fixed it, but rivers are complexed and you got many scenarios that could happening depending on the rivers shape, depth, flow of water, and rapid changes during the seasons 

[Kwasaki]

Speaking as an expat ex - builder for what its worth build up the ground level of your foundation footings of the house you propose to build as high as its necessary pretty simple really. 

[Kwasaki]

The questions are have the other house's nearby been flooded. 

 

Make sure you can build higher than the Temple. ????

[The Fugitive]

My area has flooded for the past two years. Before that it hadn't for ten years. My Mother-in-law's house becomes uninhabitable. Tessabann operate boats for residents to escape/access their homes. We've been buying lorry loads of soil with a view to demolishing and rebuilding Mum's house. The family don't wish to move.

[ubonr1971]

2 hours ago, Kwasaki said:

Speaking as an expat ex - builder for what its worth build up the ground level of your foundation footings of the house you propose to build as high as its necessary pretty simple really. 

But as a builder do you think its easier to build a house on stilts or raised house with steps up etc. Does this save the hastle of adding soil and building retainer walls?

[ozimoron]

3 minutes ago, ubonr1971 said:

But as a builder do you think its easier to build a house on stilts or raised house with steps up etc. Does this save the hastle of adding soil and building retainer walls?

Where I come from most houses were built in stilts so I'm biased. Traditional Thai houses are often built on stilts as you are no doubt aware. They keep crawlies out, are cooler and don't require much site works which can be eroded away. On any sloping land or subject to floods or strong water runoff I would definitely go this way with a kitchen and bathroom built at ground level out the back or on the highest point. Timber floors are much cooler and nicer as well.

[Kwasaki]

1 hour ago, ubonr1971 said:

But as a builder do you think its easier to build a house on stilts or raised house with steps up etc. Does this save the hastle of adding soil and building retainer walls?

No not for me I prefer to drive to the house,  unless you want get a boat to it at certain times of the year.

As they say up to you. 

[liddelljohn]

We have some property near kabinburi 3 rai next to Phrapong river between kabin and Sakaeo  in rainy season it would be flooded  but we raised it 1.5m  22 years ago and it never gets flooded now the wate gets to half a meter from top  but the crucial thing is to put trees and plants all around the sides to reinforce the banks  once the plants have matured  in as little as 18months then the whole thing is strong stable  and will not erode  we now have for last 21 years   30 rental rooms on the site and a shop . the road next to our site gets  a bit of water on it but locals can still pass by we are also only 30m from main 33 Highway 

[DavisH]

On 1/5/2023 at 4:50 PM, Hummin said:

Another thing to consider, are you on a outer bend of the river? And is the river a natural walled river or have they done any reinforcment to it? 
 

If you are on a outer bend, the river will continue to digg in to your borders and finely cave in little by little. If it is straight, them it is not that crucial depending on if its a wide section of the river or a more narrow one. 

The land can still erode even on a straight part. This happened to the families Land which is on the Mae klong river (the one that runs through Kanchanaburi to Ratchaburi). For better or worse, they has to sell that land (I couldn't afford to buy it off them, sadly). The new owners have cleared and grassed it. They will need to build a retaining wall to stop the loss of soil, which is quite expensive. Havng said that, this river has never flooded the local houses. So for the OP it will depend on the location of the house relative to the river. Some areas arevery low lying and flood annually, such as Ayutthaya. 

[DavisH]

On 1/5/2023 at 8:15 PM, ozimoron said:

Where I come from most houses were built in stilts so I'm biased. Traditional Thai houses are often built on stilts as you are no doubt aware. They keep crawlies out, are cooler and don't require much site works which can be eroded away. On any sloping land or subject to floods or strong water runoff I would definitely go this way with a kitchen and bathroom built at ground level out the back or on the highest point. Timber floors are much cooler and nicer as well.

The timber floors in my wife's family place are probably close to 100 years old. They are hard as a rock. Never had to treat for termites! I doubt that type of timber can be bought anywhere now, unless it's old used timber. The house is defnitely cooler that our brick/stone place. Only in the day it gets hot upstairs but being timber and not that well insulated it cools very fast (unlike concrete). 

[DavisH]

On 1/5/2023 at 6:07 PM, The Fugitive said:

My area has flooded for the past two years. Before that it hadn't for ten years. My Mother-in-law's house becomes uninhabitable. Tessabann operate boats for residents to escape/access their homes. We've been buying lorry loads of soil with a view to demolishing and rebuilding Mum's house. The family don't wish to move.

Good job! Someonereclaimed near my village and they have raised the road over a meter above the road level (which sould be safe against another 2011 flood). Not sure what they will build there. 

[4MyEgo]

On 1/5/2023 at 6:37 PM, ubonr1971 said:

Therefore I think the 2 options are:

1. Both proposed houses have to be on stilts ie raised by a meter or 2

or

2. Add soil and raise the land in only the areas where the houses are. If the flooding event happens again then only the lower areas will be flooded. 

 

What about drainage? Should we be putting slotted ag pipe all the way around the entire boundary on the inside of the proposed concrete wall that we intend to build. The run off could be at the river end. A pipe going down to the river. Would this be advisable to you think?

We have lived in this village since 2015 and we live opposite a river and the main road (single lane either side runs past our place and through the village.

 

Facing our place from the road we have a house on the right on stilts and on the left vacant land and next to that another house on stilts, both those houses and the land (rice field) are below road level and the river rises every year, even though the river is below road level on the opposite side by a good say 5 metres slopping, it did rise one year right up to our front gates and wanted to make it's way to our place, however would fall back to the road as we filled our land about a metre above the road level, good choice for us.

 

Unfortunately for our neighbours, they had to get into little dinkies or use large laundry type low black buckets to get to their houses as it was bad and when the river subsided they had to wait weeks for the water to disappear. 

 

From your rough plan, it looks as thought your looking to build at the back closer to the river, I would suggest you build your house more to the middle of the land away from the river after you have raised the land with soil if the river is at the same level as your land, e.g. a metre higher.

 

Concrete fencing, not unless your confident that those laying the foundations know about how far down you have to go and how high you can go, otherwise it will go over, especially if they don't put in any weep holes.

 

As for water run off from gutters etc run underground channels and pits about every 3 metres so as to slow the water run off, i.e. when one pit fills up to about 3/4 level it will continue onto the next fit and so on until it goes straight out to the river behind your land, (only water run off of course). As the river is on the other side of the road at our place, our water run off goes straight out to the road on either side of our place, i.e. one pipe on the left and one on the right facing the house, no one can see them as we have made gardens about a metre and a half on either side and created a slight drop so the water doesn't gush out, more of a fall into the garden and then works it's way across our layback/driveway access point on one side and along the front of our place meeting up with the water on the other side then disappears down into the rice field.

 

On 1/5/2023 at 6:37 PM, ubonr1971 said:

Its hard to decide if we should make an offer and buy this land. Any opinions are appreciated

It all boils down to price, what you should look at is how much fill your going to require, e.g. 150 truck loads x say 600 baht per truck = 90,000 baht which shouldn't be added to the price but reduced from the price, also being a main road, if it has more than one lane either side of the road, then that could have a detrimental overall appeal due to traffic noise, also being on a laneway could also be an issue for some, i.e. higher risk of break ins ?

 

The most important part you should consider is, what do I get if my relationship goes wrong after I outlaid XYZ $, this is something 90% of farangs don't think about because they think relationships last forever, well we would all hope that is the plan.

 

I am 15 years happily married and continue to go strong, however, I have only invested 10% of my worth here in a beautiful house and if my relationship falters for whatever reason, then the house and everything else is hers, whereas my assets offshore are mine, i.e. plan B.

 

See it everyday here, farangs spending everything they have building a house, buying a new care, etc, etc, and when it hits the fan, they don't have a plan B.

 

Anyways, hope the above assists, if at the end of the day the price of the land and cost to build is too much, you can always look at at townhouses, villa's, condominiums, which you can put in your name, it might not be ideal, but has less risk in you rendering a loss if the river did rise, so to speak.

[falangUK]

On 1/5/2023 at 2:55 PM, Sheryl said:

Stilts. (Or don't but at all which would be best advice. Note that Flooding on the whole keeps getting worse here). 

 

And see if there is scope for creating some sloping  channels for water run off a2ay ftom the hoysr.

 

Do not assume lack of neighbors/privacy  makes the land valuable. Often the reverse is true in Thailand. Thais do not like to live far from other houses...and will consider far to be anything not in clear earshot.

Is there a way to Check the long term flood risk for an area in Thailand? 

[ubonr1971]

On 1/8/2023 at 8:12 AM, 4MyEgo said:

Concrete fencing, not unless your confident that those laying the foundations know about how far down you have to go and how high you can go, otherwise it will go over, especially if they don't put in any weep holes.

Do you mind if I ask how far down do the foundations have to go? Whats the legal height limit or does that depend on the province? 

 

Weep holes?... Are they just holes in the concrete to allow the water to move out? Where are the holes located exactly?

 

thanks

[blackcab]

Do check the title deed carefully, as you may possibly be in a situation where you have two different grades of land title on the same plot. I have seen land before where the land further back from the river was classed as NS4 chanote land, but the land closer to the river was of a much lesser title.

 

This was because the land closest to the river was formed by alluvion, which would make you the riparian owner. As such you normally have the right to plant and harvest on alluvion land, but not necessarily to construct a building. I note from your plan above that you want to situate a house closest to the river, so it would be good to check.

 

Make very certain that the land has the correct concrete surveying pegs in place and that there is no (or minimal) land formed by alluvion in the plot.

[Kwasaki]

1 hour ago, ubonr1971 said:

Do you mind if I ask how far down do the foundations have to go? Whats the legal height limit or does that depend on the province? 

 

Weep holes?... Are they just holes in the concrete to allow the water to move out? Where are the holes located exactly?

 

thanks

Ask locally, on compacted ground for the average fench building with block or brick wall 50 cm deep foundation obviously the higher the wall more foundation depth. 

[4MyEgo]

8 hours ago, ubonr1971 said:

Do you mind if I ask how far down do the foundations have to go?

It all depends on the land, that said, generally speaking 1/3 - 1/2 of the height of the fence.

 

8 hours ago, ubonr1971 said:

Whats the legal height limit or does that depend on the province? 

This also depends where you live, we live in a village, no approvals required, so we went up to 1.8 metres.

 

8 hours ago, ubonr1971 said:

Weep holes?... Are they just holes in the concrete to allow the water to move out?

Yes, holes that go into the concrete fence to allow water to weep through the fence.

 

8 hours ago, ubonr1971 said:

Where are the holes located exactly?

Generally speaking, they are located at the external, lower area of the walls, i.e. if the land is raised and your walls, start from the lower section of your land outside, so any water trapped underground weeps through the weep holes.

 

I am pretty sure if you do enough research via Google or YouTube, you can find enough information on this.