vapor barrier 3/4 inch stone

[charleskerins]

Accompanied a friend to meet builder and architect   to go over build plans.     A little confused as to Thai building methods   maybe members can help out.

*Piers   there are 18 piers I asked the guy if they were going to put crushed stone underneath the concrete to draw moisture he looked at me strangely and said yes.

*  girders  -wth are these horizontal  poured concrete ??  

* so then i asked if they were going to put plastic down and crushed stone over floor before pouring concrete "no they don't do that in Thailand upon further questioning it was an option on the plan but too expensive?

*  I showed them a video of a plate tamper asked them if they were going to use it -no   it's up high so don't need to use it? 

If anyone can decipher any of this feel free to give it a go    

 

Thanks

 

[Dr B]

13 hours ago, charleskerins said:

Accompanied a friend to meet builder and architect   to go over build plans.     A little confused as to Thai building methods   maybe members can help out.

*Piers   there are 18 piers I asked the guy if they were going to put crushed stone underneath the concrete to draw moisture he looked at me strangely and said yes.

*  girders  -wth are these horizontal  poured concrete ??  

* so then i asked if they were going to put plastic down and crushed stone over floor before pouring concrete "no they don't do that in Thailand upon further questioning it was an option on the plan but too expensive?

*  I showed them a video of a plate tamper asked them if they were going to use it -no   it's up high so don't need to use it? 

If anyone can decipher any of this feel free to give it a go    

 

Thanks

 

1   I have no idea what you mean by "put crushed stone underneath the concrete to draw moisture" in relation to piers. By piers do you mean piles or columns? Any load bearing concrete should be in contact with the stiff or dense soil or rock which is going to support it.

2   If the structure has horizontally poured reinfod concrete beams that is perfectly normal.

3   Unfortunately the vast majority of Thai builders do not understand the concept of vapour proof barriers, and think that concrete is waterproof so that is OK. The fact is that moisture will then rise through the concrete allowing the water to evaporate at the surface, leading to efflorescence. This can be seen all over the place in walls and columns just above the slab. I even have a video of concrete being poured onto a polythene sheet, not adequately lapped with any adjacent sheet, and placed on top of the steel mesh!

4   Again not sure what you mean by a "plate tamper". I am familiar with vibrating plates for compacting fill, which we have used here, and with poker vibrators for compacting concrete. These are also available here for less than Bt 3,000, but are very rarely used. I have one, and once the builders saw what it did they loved it, and even used it to vibrate the concrete in the kitchen units! When concrete is not vibrated it leaves air voids (honeycomb concrete), which they just patch over with mortar. This will allow the rebar to easily rust in the high humidity conditions, all hidden away from view.

Hope that helps.

[Dr B]

Sorry "reinfod" should have been "reinforced"

[itsari]

13 hours ago, charleskerins said:

Accompanied a friend to meet builder and architect   to go over build plans.     A little confused as to Thai building methods   maybe members can help out.

*Piers   there are 18 piers I asked the guy if they were going to put crushed stone underneath the concrete to draw moisture he looked at me strangely and said yes.

*  girders  -wth are these horizontal  poured concrete ??  

* so then i asked if they were going to put plastic down and crushed stone over floor before pouring concrete "no they don't do that in Thailand upon further questioning it was an option on the plan but too expensive?

*  I showed them a video of a plate tamper asked them if they were going to use it -no   it's up high so don't need to use it? 

If anyone can decipher any of this feel free to give it a go    

 

Thanks

 

As with all foundations it depends a lot on the location and you really can not say to a Thai engineer thats not how we do it at home. 

I have seen what happens in the Chiang Mai area and what you see is they lay a 120 cm x 120 cm concrete pad under each column. The pad is in my experiance just above the water table which is around 1.5 meters down  and is sitting on fine natural sand.

If the building is going to be above a certain level then the engineer will require piling under each column which costs considerably more. Pads seem to be the choice for the average house.

[charleskerins]

30 minutes ago, Dr B said:

1   I have no idea what you mean by "put crushed stone underneath the concrete to draw moisture" in relation to piers. By piers do you mean piles or columns? Any load bearing concrete should be in contact with the stiff or dense soil or rock which is going to support it.

2   If the structure has horizontally poured reinfod concrete beams that is perfectly normal.

3   Unfortunately the vast majority of Thai builders do not understand the concept of vapour proof barriers, and think that concrete is waterproof so that is OK. The fact is that moisture will then rise through the concrete allowing the water to evaporate at the surface, leading to efflorescence. This can be seen all over the place in walls and columns just above the slab. I even have a video of concrete being poured onto a polythene sheet, not adequately lapped with any adjacent sheet, and placed on top of the steel mesh!

4   Again not sure what you mean by a "plate tamper". I am familiar with vibrating plates for compacting fill, which we have used here, and with poker vibrators for compacting concrete. These are also available here for less than Bt 3,000, but are very rarely used. I have one, and once the builders saw what it did they loved it, and even used it to vibrate the concrete in the kitchen units! When concrete is not vibrated it leaves air voids (honeycomb concrete), which they just patch over with mortar. This will allow the rebar to easily rust in the high humidity conditions, all hidden away from view.

Hope that helps.

Just lost my entire response because internet went out  and I am a slow typer .

First thanks  for your response    #1  i would put a couple inches of stone before pier is poured   #2 understood  just not used to seeing them  .

#3   in US  before pouring concrete on  inside  floor we would run a plate tamper(vibrating) to compact the soil  cover area with plastic ,then wire mesh ,then 3/4 stone minimum 4 inches then 3500 psi concrete    the architect has that as one of the options on the plan but both he and the builder said it wasn't necessary because we are "up high"   couldn't figure it out  now maybe i have do they think the plastic is for outside water protection???  poker vibrator great idea thanks  feedback is welcomed 

[charleskerins]

10 minutes ago, itsari said:

As with all foundations it depends a lot on the location and you really can not say to a Thai engineer thats not how we do it at home. 

I have seen what happens in the Chiang Mai area and what you see is they lay a 120 cm x 120 cm concrete pad under each column. The pad is in my experiance just above the water table which is around 1.5 meters down  and is sitting on fine natural sand.

If the building is going to be above a certain level then the engineer will require piling under each column which costs considerably more. Pads seem to be the choice for the average house.

I didn't say thats not how we do it at home  (but it is)   there will be 18 piers   (holes seem large maybe they are going to pour a pad as you stated )  My concern is the poured concrete floor between the horizontal columns      no vapor barrier no soil compaction no stone 

[novacova]

16 minutes ago, charleskerins said:

couldn't figure it out  now maybe i have do they think the plastic is for outside water protection???

If a waterproof vapor barrier is installed underneath the concrete, then it’s imperative that no moisture is able to enter between the concrete and the barrier. One leak can cause havoc being worse than not having the barrier. 

[itsari]

11 minutes ago, charleskerins said:

I didn't say thats not how we do it at home  (but it is)   there will be 18 piers   (holes seem large maybe they are going to pour a pad as you stated )  My concern is the poured concrete floor between the horizontal columns      no vapor barrier no soil compaction no stone 

Mostly what you see is they lay prefabricated concrete slabs across the horizontal beams and then lay concrete over the top of around 10 cm thickness . The prefabricated slabs are suspended froom the ground normally and that would stop any need for a vapour barrier.

[charleskerins]

1 minute ago, itsari said:

Mostly what you see is they lay prefabricated concrete slabs across the horizontal beams and then lay concrete over the top of around 10 cm thickness . The prefabricated slabs are suspended froom the ground normally and that would stop any need for a vapour barrier.

Okay seems like you may be saving me a fight with the builder -maybe that's what they meant when they said" up high"    Here's the problem I can't quite visualize what you are describing.  Are you saying they cover the entire surface with prefabricated slabs ?  Why pour the concrete then?   I' m anxiously waiting your response   would be nice if I could read Thai

[itsari]

1 minute ago, charleskerins said:

Okay seems like you may be saving me a fight with the builder -maybe that's what they meant when they said" up high"    Here's the problem I can't quite visualize what you are describing.  Are you saying they cover the entire surface with prefabricated slabs ?  Why pour the concrete then?   I' m anxiously waiting your response   would be nice if I could read Thai

The prefabricated concrete slabs are only 40 cm wide and 5 cm thick but have prestressed steel in them. The concrete is therefore strengthing the finished floor and leveling up as well. It is an affective building method.

Also the beams they build between the columns are very strong and are self supporting as well.

[itsari]

7 minutes ago, charleskerins said:

Okay seems like you may be saving me a fight with the builder -maybe that's what they meant when they said" up high"    Here's the problem I can't quite visualize what you are describing.  Are you saying they cover the entire surface with prefabricated slabs ?  Why pour the concrete then?   I' m anxiously waiting your response   would be nice if I could read Thai

There can be a problem with thai builders when it comes to lack of foundations on additions like a staircase for example . In time the staircase sinks at a different rate than the rest of the house . The additions should be tied into the foundations to stop that happening .

Worth checking as i have two staircases leading to the house that are sinking . Apparently a common problem in Thailand

[charleskerins]

5 minutes ago, itsari said:

The prefabricated concrete slabs are only 40 cm wide and 5 cm thick but have prestressed steel in them. The concrete is therefore strengthing the finished floor and leveling up as well. It is an affective building method.

Also the beams they build between the columns are very strong and are self supporting as well.

How are the slabs attached to the piers /girders       my friend said they tried to explain this to me yesterday.

[charleskerins]

1 minute ago, itsari said:

There can be a problem with thai builders when it comes to lack of foundations on additions like a staircase for example . In time the staircase sinks at a different rate than the rest of the house . The additions should be tied into the foundations to stop that happening .

Worth checking as i have two staircases leading to the house that are sinking . Apparently a common problem in Thailand

so there are three steps leading up to the house -they should be tied into the ? girders?

[itsari]

1 minute ago, charleskerins said:

so there are three steps leading up to the house -they should be tied into the ? girders?

Yes, that is correct . Then the steps will sink at the same rate as the house 

[itsari]

4 minutes ago, charleskerins said:

How are the slabs attached to the piers /girders       my friend said they tried to explain this to me yesterday.

They are simply laid on top of the concrete beams. No fixings required 

[charleskerins]

24 minutes ago, itsari said:

They are simply laid on top of the concrete beams. No fixings required 

oh interesting      thanks much appreciatednmnm

[charleskerins]

51 minutes ago, novacova said:

If a waterproof vapor barrier is installed underneath the concrete, then it’s imperative that no moisture is able to enter between the concrete and the barrier. One leak can cause havoc being worse than not having the barrier. 

I agree but with some members help   i think i understand why no vapor barrier is needed .

concrete piers on pad   ,horizontal concrete girders off the ground, prefab concrete slabs (like you see in commercial construction) on top of girders than poured concrete floor.

[Luuk Chaai]

1 hour ago, charleskerins said:

How are the slabs attached to the piers /girders       my friend said they tried to explain this to me yesterday.

they are not ..  just laid on top

and if you have the $$$$$   pour cement over the (dirt floor )

the black hose you see is the  termite prevention system they spray every year

[charleskerins]

bottom photo is the prefabricated panels before concrete pour?  and the girders are supported by steel underneath?

[Kinok Farang]

A visqueen vapour barrier should be put on top of the crushed stone then sand sub base of your floor.Then raised re-mesh and then your concrete.

The vapour barrier should overlap your inside skin of brickwork then a damp proof course rolled out on top of that at finished floor height.

Of course that never happens in LOS.

[charleskerins]

31 minutes ago, Kinok Farang said:

A visqueen vapour barrier should be put on top of the crushed stone then sand sub base of your floor.Then raised re-mesh and then your concrete.

The vapour barrier should overlap your inside skin of brickwork then a damp proof course rolled out on top of that at finished floor height.

Of course that never happens in LOS.

understood but that is if your concrete floor is in contact with the ground  in this case it is not            

[CLW]

23 hours ago, Kinok Farang said:

A visqueen vapour barrier should be put on top of the crushed stone then sand sub base of your floor.Then raised re-mesh and then your concrete.

The vapour barrier should overlap your inside skin of brickwork then a damp proof course rolled out on top of that at finished floor height.

Of course that never happens in LOS.

Agree. But this works only on a flat surface. How to do with the situation at above picture? Raised foundation on slabs. Or is the distance to the soil sufficient?

[Kinok Farang]

42 minutes ago, CLW said:

Agree. But this works only on a flat surface. How to do with the situation at above picture? Raised foundation on slabs. Or is the distance to the soil sufficient?

DPC ,(damp proof course) could be rolled out on top of your concrete ringbeams directly under your floor slabs.There is no need for visqueen then.

If you want to be posh you can cover the earth with a couple of inches of concrete to stop any weeds that could possibly grow.

[Dr B]

On 7/12/2024 at 9:32 AM, charleskerins said:

Just lost my entire response because internet went out  and I am a slow typer .

First thanks  for your response    #1  i would put a couple inches of stone before pier is poured   #2 understood  just not used to seeing them  .

#3   in US  before pouring concrete on  inside  floor we would run a plate tamper(vibrating) to compact the soil  cover area with plastic ,then wire mesh ,then 3/4 stone minimum 4 inches then 3500 psi concrete    the architect has that as one of the options on the plan but both he and the builder said it wasn't necessary because we are "up high"   couldn't figure it out  now maybe i have do they think the plastic is for outside water protection???  poker vibrator great idea thanks  feedback is welcomed 

All good. Are you familiar with "capillary action". This is based on surface tension, which is what makes your wine climb up the inside of the glass. If you have a small glass tube, called a capillary tube, the suface tension will pull water up the inside above the level of the water surface. Now if you have sand in the ground, you may have a "water table" say 2 m down. That is the level at which the water sits, but above this is a capillary zone, where some of the water gets drawn up by surface tension becasue of the very small gaps between the sand grains. Now if you cast a slab on ground, that will stop the soil from being exposed to the air and the water from evaporating. As a result you will get a dome of damp ground under the house, which will probably reach the underside of the slab. If you don't have a proper vapour proof barrier, then the damp will migrate through the concrete, up the walls a certain distance, and then evaporate. That will leave behind the minerals in the water (efflorescence), and nasty white staining which makes the paint peel off. All of the row of 26 houses opposite ours have that problem, as well as most other houses with ground bearing slabs. Thais see concrete used as walls, with the rain running down the outside, so think that concrete is waterproof. Not true. It is low permeability but not water proof, and it needs to be vapour proof. It is very hard to get a good vapour proof barrier here as there are no fittings for the necessary penetrations. In the end I used a surface waterproof membrane applied in two coats over the top of the slab for the enclosed ground flor rooms.

Compacting the soil with a tamper is a good idea. We compacted the crusher run under our slab. Having done that and made it good and dense, you want to get the concrete slab supported by that compacted soil, but I very often see Thais putting down a layer of loose sand in between. I even see this on highway slabs. I have no idea why. It makes no sense to place a layer of loose sand between compacted soil and good concrete. Be careful with the water cement ratio of the concrete. More water means weaker concrete, but they love to add more water because it makes it flow more easily. That is where the vibrator comes in. Once they get the hang of it they will love it!

Good luck

[Dr B]

If you want to have a suspended floor without a vapour proof barrier that is, of course, fine but the void between the ground and the underside of the floor should be ventilated, just as it was with all timber floors. If it is not ventilated (just a few opening on all sides for the air to blow through), then it will become damp, the underside of the suspended floor will become damp, and that dampness will come through into the house eventually.

[charleskerins]

17 hours ago, Kinok Farang said:

DPC ,(damp proof course) could be rolled out on top of your concrete ringbeams directly under your floor slabs.There is no need for visqueen then.

If you want to be posh you can cover the earth with a couple of inches of concrete to stop any weeds that could possibly grow.

Yes    i asked about crushed stone and plastic for weeds and they chuckled

[charleskerins]

23 hours ago, Dr B said:

All good. Are you familiar with "capillary action". This is based on surface tension, which is what makes your wine climb up the inside of the glass. If you have a small glass tube, called a capillary tube, the suface tension will pull water up the inside above the level of the water surface. Now if you have sand in the ground, you may have a "water table" say 2 m down. That is the level at which the water sits, but above this is a capillary zone, where some of the water gets drawn up by surface tension becasue of the very small gaps between the sand grains. Now if you cast a slab on ground, that will stop the soil from being exposed to the air and the water from evaporating. As a result you will get a dome of damp ground under the house, which will probably reach the underside of the slab. If you don't have a proper vapour proof barrier, then the damp will migrate through the concrete, up the walls a certain distance, and then evaporate. That will leave behind the minerals in the water (efflorescence), and nasty white staining which makes the paint peel off. All of the row of 26 houses opposite ours have that problem, as well as most other houses with ground bearing slabs. Thais see concrete used as walls, with the rain running down the outside, so think that concrete is waterproof. Not true. It is low permeability but not water proof, and it needs to be vapour proof. It is very hard to get a good vapour proof barrier here as there are no fittings for the necessary penetrations. In the end I used a surface waterproof membrane applied in two coats over the top of the slab for the enclosed ground flor rooms.

Compacting the soil with a tamper is a good idea. We compacted the crusher run under our slab. Having done that and made it good and dense, you want to get the concrete slab supported by that compacted soil, but I very often see Thais putting down a layer of loose sand in between. I even see this on highway slabs. I have no idea why. It makes no sense to place a layer of loose sand between compacted soil and good concrete. Be careful with the water cement ratio of the concrete. More water means weaker concrete, but they love to add more water because it makes it flow more easily. That is where the vibrator comes in. Once they get the hang of it they will love it!

Good luck

Thanks -i know they like the water in the crete     no!

[CLW]

On 7/13/2024 at 3:08 PM, Kinok Farang said:

DPC ,(damp proof course) could be rolled out on top of your concrete ringbeams directly under your floor slabs.There is no need for visqueen then.

If you want to be posh you can cover the earth with a couple of inches of concrete to stop any weeds that could possibly grow.

Thanks, yes. DPC is what I was looking for. So something like this in below pictures, right? Is it available in Thailand?

 

[CLW]

@Kinok Farang Since I did not find DPC as a roll, can these products below used equally? One is bitumen paint, the other waterproof cement slurry. Thank you!

[charleskerins]

Actually have never seen that on a job before is that because all the jobs i have been on had a vapor barrier below the slab???   Can you lay this on before the first course of block?  https://gbr.sika.com/en/construction/waterproofing/mortars-and-coatingstypea/sika-damp-proofingslurry.html