Sealant For Leaking Flat Roof

[naammanow]

My flat roof is still leaking. I have used Beger primer, followed by two coats of Beger "synotex" roof paint. Thought that would fix the roof leaks, alas to no avail. Anything I can add on top of this that is better? And wonder if anybody can recommend any products that will actually seal it? Alternatively, can I pour a waterproof concrete screen on top and creating a slope so the water will run of easier? Thanks!

[Pacificperson]

What material is the roof made of?

[naammanow]

What material is the roof made of?

It's made of concrete.

[Pacificperson]

First, if your roof is flat, you cannot use a water based paint to seal it. The paint will not last where there is any puddling.

The best solution seems to be to use a two-part pourable epoxy for any cracks. Open them up with an angle grinder and pour it into them. Then, paint the whole with a 100% silicone paint. Its not cheap, but it will last for several years. It will also cut your AC bills.

[cheeryble]

If all else fails you can use what I used on a balcony in England........glassfibre

Edited August 3, 2011 by cheeryble

[bbradsby]

sorry but no one can recommend a real fix sight unseen - have any pix, roof tech info/specs on what your roofing assembly is at present. More info puhleeze!

[lopburi3]

If all else fails you can use what I used on a balcony in England........glassfibre

Actually it may not be common but in 1974 we used boat fiberglass to seal a badly leaking roof in Vientiane, Laos and it did work.

[meatboy]

i had a good mate back in the uk who is a roofer and he used to say never touch a flat roof always one big headache,once lived in the uk with a balcony that always leaked in the end built a false slopeing roof success. i am having trouble with a slopeing roof so i dont envy you.

[cheeryble]

If all else fails you can use what I used on a balcony in England........glassfibre

Actually it may not be common but in 1974 we used boat fiberglass to seal a badly leaking roof in Vientiane, Laos and it did work.

It's not so difficult mainly about adjusting the hardener to get the curing time right for the temperature....not to quick to work on it, but not too slow.

I've also developed a way of injecting polyester resin (as in fibreglass) through small drilled holes to repair loose tile parquet floor problems, and it just takes a little pre-testing to get a practicable hardening time.

Works a treat, you don't have to take any tiles up, use an 1/8th inch bit and a veterinary syringe (no needle) whose nozzle fits the hole snugly, and it will even sort out a crumbly mortar layer underneath (not uncommon) as the liquid just oozes through everything loose. Almost invisible afterwards. I saved a ton of hassle and a good bit of money for a re-lay.

Edited August 4, 2011 by cheeryble

[naammanow]

I am seriously thinking making a false sloping roof. Something with steel and metal long sheets. That should solve the problem.

Think the bitumen/rubber solution will be difficult in such a hot hot climate as Thailand has.

The fiber glass solution looks complicated etc.

Anyway, will have a builder looking at as well I think. The roof is pretty large, 5 x 14 meters.

Wish I could just pour a "liquid substance" over the roof or paint it that will create a permanent barrier; however think difficult to achieve.

Next time, no flat roofs I suppose............

[cheeryble]

Wish I could just pour a "liquid substance" over the roof or paint it that will create a permanent barrier; however think difficult to achieve.

If you are well off two part epoxy deck paint and a roller, two coats.It will reflect the heat too.

Edited August 4, 2011 by cheeryble

[Pacificperson]

If you do the proper preparation work, then 100% silicone paint should do the job for you. It is not cheap. I am not in Thailand so I cant give you a price. Using our local prices, it would cost about 18,000 B to for materials.

You need two coats and coverage is 500 sq. ft./ 5 gallon bucket per coat. Cost here is $200.00 / 5 gallon bucket.

Fiberglass would be more expensive and it would still need a coating to protect it from the sun.

[bbradsby]

Again... no one can recommend a real fix sight unseen - have any pix, roof tech info/specs on what your roofing assembly is at present? We know your structure is concrete from your post above, but there should be a membrane of some sort. In Asia, these can be over, or even under the concrete you see, in which case the concrete you see is not the structure and there's a structure concealed below. More info puhleeze! Pix of an area that appears to be degrading, and one at a parapet wall-to-roof corner would maybe help me get an idea of what you have in place.

[Deke]

I had a shophouse at one time with a flat concrete roof that leaked. My solution was to lay tile on the roof and increase the slope to the drains at the same time. It worked and also gave me some semi-usable outdoor space.

You should try to more or less seal the leaks first and then let the tilers go to work.

[katabeachbum]

If your structure can carry another 20 ton, I would consider covering the roof again with 10 cm/4 inches of waterproof(ganzum) 280 concrete. wire mash steel as rebars. finish off with good slopes and shiny cement. approx 20.000 baht and long lifetime

[bbradsby]

That's a big 'if' to sleep under every night. To the OP, if you consider concrete may form all or part of the solution, you need a structural engineer to review your existing conditions before thinking about adding any new, much less a concrete, load.

[cheeryble]

Structural engineer, false roof, new concrete, tiles.....

Maybe fibreglass or epoxy deck paint ain't such a silly idea. They will do the job.

Edited August 8, 2011 by cheeryble

[meyori]

We had problem with leaking roof for many years even we tried a lot different things. Finally we found a company does form spray in Hua Hin. It's not the cheapest way, but it has been working out great. No need to worry every time we get rain is such a relief.

This company goes all over Thailand to do their jobs.

[naammanow]

We had problem with leaking roof for many years even we tried a lot different things. Finally we found a company does form spray in Hua Hin. It's not the cheapest way, but it has been working out great. No need to worry every time we get rain is such a relief.

This company goes all over Thailand to do their jobs.

Thanks Meyori and am willing to give them a try. Do you have any contact info re said company, I am in Chiang Mai so if they cover Thailand in general, they will also have outlet here I suppose. Thanks!

[katabeachbum]

We had problem with leaking roof for many years even we tried a lot different things. Finally we found a company does form spray in Hua Hin. It's not the cheapest way, but it has been working out great. No need to worry every time we get rain is such a relief.

This company goes all over Thailand to do their jobs.

Thanks Meyori and am willing to give them a try. Do you have any contact info re said company, I am in Chiang Mai so if they cover Thailand in general, they will also have outlet here I suppose. Thanks!

terrible solution IMHO

the foam is applied under the roof, so you keep the surface leaks and thus water is collected in roof structure. Lifetime for rebars in concrete or steel roofstructure reduced to.......well significantly reduced

a low weight solution would be to apply latex membrane to dry and clean concrete. Reinforce with fiberglass in all joints and over visible cracks. Cover with tiles (in synthetic glue) to avoid UV and mechanical wear and tear. 200 baht/sqm tiles, cost would be appox 6-700 baht/sqm.