Weeping Cement Walls

[jaideeguy]

My house seems to have been built w/o a vapor barrier....contractor saving small bhatt and costing me big bhatt now. House built 10 yrs ago, bought 2nd hand 5 yrs ago and i've repainted a couple of times, using concrete sealer and good quality primer 2 coats and then 2 coats of paint, yet after 2 months these ugly blisters reappear going up about 20 inches. if punctured, there is a whitish powder under them. both inside and outside.

Seems obvious that builder cheated on plastic vapor barrier under slab.

Now, what to do?? i've thought of 'wainscoating' it up a meter with concrete board, plywood or whatever, but that may present other problems with hiding places for insects. Wallpaper would just blister as well, i'm sure.

anyone else have the same problem and or a solution/suggestion??

[BEENTHEREDONETHAT]

You might consider tiling up 20 inches.

[jaideeguy]

Thought of that, but unless existing paint were removed or grooves cut into cement, the tiles won't stick and it would be a real messy job.

[BEENTHEREDONETHAT]

Thats true oh well back to the drawing board.

[lopburi3]

Paint is removed and surface scared for new cement layer prior to laying tiles. Very quick and inexpensive (at least on inside of rooms). Outside you might want to leave an unpainted inch or two at bottom of walls to allow evaporation. Our only problem was in rear of house so outside was not an issue.

[tjo o tjim]

Sorry, but is the wall underground, or is the slab just on grade? Is the blistering localized or all over?

If the problem really is that the moisture barrier is missing, you can dig a sump to help lower the water table locally, or cut the slab and put in a french drain.

Cheap and dirty the tiles will win though.

[chownah]

I think that tjo o tjim has the right idea....first do everything you can do to improve your drainage and lower the water table under the house. This can sometimes be a simple thing like digging some trenches to drain the water away or it can be complicated like building multiple sumps with pumps. If it seems too difficult to fix the drainage then go ahead with somehow covering up the problem but you will probably always have a humidity problem so then you need to put some extra effort into ventilation.

chownah

[jaideeguy]

Thanks for the feedback guys.....Yea, drainage may help as the original builder built on un compacted soil and it looks like the weight of the structure has lowered the house pad. I don't see any way to drain off the underground moisture/water table so may have to go with just covering up the <deleted>$%^&&*ing mistake.

Tile seems logical, but you know the preparation to tile over three or four coats of paint over cement render and hollow block is gonna be a messy job. dust, and then to cut grooves so the tile can stick....not my idea of a fun project.

is there any adhesive that i can apply to the 4Xpainted over cement surfaces that will hold tile without doing the grooves???

another idea that i had would be to glue some of that concrete board [shera?] that has the fake wood grain and cap it with some wood trim....but then i still have to come up with an adhesive that will hold it securely.

re: ventalation, the house is quite well ventalated with those spinners on the roof and daytime all windows are open with fans blowing constantly, so what else can i do to vent??

[yorkman]

ummm ok here's a thought.

I have back in the uk a very old house (1600's) that had just been plonked on the ground, no vapour barrier and had exactly the same problems. The thing is, if you just try and cover it over with tiles or whatever, they just blow off the wall, sooner rather than later.

Construction is different of course, so I don't know how you could retrospectively fit a damp proof course in a thai house. However, what I got was an injection treatment at the base of the walls. That was 12 years or so ago and I have not had problems.

Whether this is available in Thailand I really don't know, but it might be worth trying to find than spending money on what is just a cover up job?

Here is a link http://www.chemicalbuildingproducts.co.uk/...p?idCategory=52

It needs to be put in under pressure though, by a contractor

[rgs2001uk]

jaidee,

suggest you google rising damp, because it sounds to me that is exactly what you have, more common than you would think.

before you do any thing drastic, such as hiding the problem by tiling etc, you need to take remedial action, if it were me the only thing i would consider is to install a damp proofing course, to eliminate your problem, before you do the cosmetic work later.

as i say read up on rising damp, and make up your own mind as to what course of action you want to take, but remember the problem wont go away if you hide it, in fact its probably the worst thing you could do, because when tiles etc start popping off walls you have big problems.

better to nip this in the bud just now.

good luck

[lopburi3]

Perhaps your good advise should take into consideration the cement piles that most Thai house have supporting there foundations. Believe it is going to be rather difficult to keep them dry. But I am not (obviously) a construction engineer.

[MahasarakhamMitch]

i used slate to create a damp course, they used this years agobefore plastic. it would be a big job , but if you hacked off the rendering around the house and bit by bit chopped out a horizontal line in the mortar, you could wack some slate in 10" at a time. It cannot be rushed but would stop rising damp.

[yorkman]

That is not quite the full solution if the house is built in the usual concrete pile/infill method used in Thailand.

You could not do that with the piles, your house would fall down , so the damp would still strike up there. And you have still got all the internal walls to consider.

As I suggested earlier, the fluid injection system is the only solution I can think of that is permanent. And this is if is available in Thailand and if it will permeate concrete. Of that I have no idea.

Ohhh, and Google "electro osmosis damp proof course"; that looks like minimal effort and mess. No experience whatever of that.........

Edited December 31, 2007 by yorkman