How to clean and waterproof a cement roof

Rep Dom

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Dec 27, 2011
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Hi I should clean and waterproof a cement roof. I dont have a karcher and dont really want to buy one.
What is the process and products to use to get it cleaned and waterproofed... :)
 

Criss Colon

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Jan 2, 2002
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As you know, a power washer is the best way to clean.
Second is a "Haitiano" or two with scrub brushes.
Depending on what you need to clean off, dirt, old sealers,
or other, you may need different cleaning products.
I think that once clean, you should use a "Lanco" silicon based sealer.
The best quality you can afford.
If you own a home in the DR, you WILL have "Filtraciones"!
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Rep Dom

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Dec 27, 2011
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Hi Criss, thanks for your answer. I'll be the guy with scrub brushes as I like to do things myself. It gives me the feeling that I've done what needed to be done... Basicly what must be cleaned is dirt and old crap leaves falling on the roof from a tree.
Why do you say, I'll have filtraciones? Is it for sure? :)
 

suarezn

Gold
Feb 3, 2002
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Speaking of filtration a friend of mine who lives in a rented house has water leaking on the roof. Issue is that the house is a two story house and someone lives upstairs. It appears that the "genius" who built the house put a water pipe inside the cement serving as the ceiling to the bottom floor house and floor for the upstairs house...big conundrum.

Anyhow he doesn't want to move, because aside from that it is a nice house and he's paying a very good price, but doesn't know what to do either because the leakage is in the main bedroom. The owner is not agreeable to breaking up the concrete from below to try to find the source of the leak...I told him to try to find some kind of sealer paint...it's all I could think of. Any ideas?
 

Criss Colon

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Jan 2, 2002
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Dominicans LOVE to embed water, and sewer pipes in the cement floors and walls!
They claim that the cement prevents leaks.
My friend had a nice condo on "Los Cazicazgos" SD.
The upstairs guy's toilet pipes leaked into his bathroom.
The ONLY way to fix those leakes is to break up the ceiling under the toilet.
Since the neighbor refused to pay for the repair of the leaks in HIS TOILET, my friend had to pay, or eat his neighbor's $HIT!
He did!
"PAY" that is!
"No es MI problema, es TU problema"!
Dominicans are such nice people!
Just ask chip!
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dv8

Gold
Sep 27, 2006
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Hi Criss, thanks for your answer. I'll be the guy with scrub brushes as I like to do things myself. It gives me the feeling that I've done what needed to be done... Basicly what must be cleaned is dirt and old crap leaves falling on the roof from a tree.
Why do you say, I'll have filtraciones? Is it for sure? :)

i will sound heartless but honest: get someone else to do the job because it is always better when someone else falls off the roof, amirite? plus, it is a whole day of work in a scorching sun. not fun. why scorching sun? because you need your roof to be clean and dry when you apply the sealant and the sealant itself can only be applied well when it is a sunny and dry day. also, it may be hard to paint on if you are not familiar with it. almost like liquid rubber.

one more tip: this whole operation (cleaning and sealing) has to be done on regular basis. we do our house once every two years, but we are very close to the ocean too.
 
Jan 5, 2006
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Other than one house which I saw with an asphaltic membrane, every attempt at waterproofing roofs that I've seen in DR involved painting the surface with some elastic coating type product.

Out of curiosity, I took to Google to see what options were available for this task, and found some interesting info. Some involved membranes, some involved a sequence of painting with various coating products, others involved a combination of membrane and coating products, and the one that I found most interesting involved products by a Canadian company called Xypex. They offer various products, but basically, they all work in the same manner. They create a chemical reaction to form a crystalline structure within the naturally occurring pores and capillaries of the concrete, which in turn seals any path for the water to penetrate the slab.

The concept sounds interesting, and different discussions which I came across on the web point to the product being very effective. It would be interesting to see if this product or an equivalent is available in DR, and what the experience/results with its use has been.
 
Jan 5, 2006
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Just went back to Xypex's website, and they do list an individual distributor for their products in DR. However, there's no info such as tel number or address; just a way to email him.
 
Jan 5, 2006
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A little more snooping around, and I found that the rep for Xypex in DR is a company called Coberdom, which lists some major projects all over the island. Now I wonder if the actually sell the product, and what the pricing is.
 

PJT

Silver
Jan 8, 2002
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White Cement

This is a cheap option to seal a cement roof. An engineer friend advised white cement is a sealer he has used to waterproof cement roofs, ones that have no tiles or membrane. You first clean the roof with a heavy application of bleach and water to rid the surface of mold, dirt, and debris. The use of a heavy broom to scrub the surface makes the job faster and efficient. Allow a bit of time to allow the bleach to kill off the mold. Hose the surface down after the wait to reduce the effects of a chemical burn of the surface by the bleach.

Purchase white cement, try 20 lbs to start. The exact amount needed depends on the size of the roof. Acquire a clean 5 gal bucket and fill it about 1/3 with water. Add sifted white cement a little bit at a time until the mix has the liquid consistancy of a milk shake, frappe, thickshake. Be mindful of the ratio amount of cement to water to be constant with your following mixes. Lightly dampen the roof surface. A hose with mist nozzle would be great. Apply the mix to the cement surface using a household broom using broad strokes in various directions. Doing this allows the white cement to fill the fine cracks and crevices, and irregular surfaces of the cement roof. It makes a great seal. PJT has waterproof a roof using this method, it has been in service for five years since the last application and there are no leaks.

Criss has offered a testimonial to Lanco silicon sealers and PJT does the same. If you desire, after doing the white cement application you have the option to add extra protection with the Lanco sealer for insurance. An awesome seal is made with a coating of the sealer and the application of a cloth (PJT forgets the name) over the wet sealer coating and then a coating of the sealer over the cloth. It has the similar quality of a membrane roof.

Good luck and Regards,

PJT
 

Chip

Platinum
Jul 25, 2007
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Santiago
It appears that the "genius" who built the house put a water pipe inside the cement serving as the ceiling to the bottom floor house and floor for the upstairs house...big conundrum.

If you have a bathroom on the second floor that is not adjacent to a wall the pipes have to go in the floor as they can't go horizontally in the block wall. The trick is to not put it in the structural part but in the subfloor.
 

Criss Colon

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Jan 2, 2002
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There is a guy on DR! who, when he built his house, he put the "Pipes" on the outside of the house.
That was always my plan, if I built.
A nice "Pipe Chase", any leaks, repairs, or re-connections",."No Problemas"!
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Chip

Platinum
Jul 25, 2007
16,772
429
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Santiago
Actually there is a new system here that has a flexible conduit, aka chase, that is installed in the walls and floors and a 1/2 pe flexible pipe inserted for the pressure system. In the event of leaks the pressure pipe is puled out and checked or replaced. It will require various inspection ports wherever the connections are made. This system is currently more expensive but I expect as it becomes more popular prices will fall.
 
Jan 5, 2006
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It would make sense to use a chase with PEX tubing for the water pipes. However; you still have the issue of sewer pipes for second/upper floor bathrooms, which have to be placed in what would be the first floor ceiling.

As for waterproofing the roof... I have not seen anything being used that makes me confident. The paints/coatings that are more widely used in DR require reapplication within 2 to 3 years. Those products by Xypex seem like they may be a long term solution to what is a very common problem.
 

Chip

Platinum
Jul 25, 2007
16,772
429
0
Santiago
It would make sense to use a chase with PEX tubing for the water pipes. However; you still have the issue of sewer pipes for second/upper floor bathrooms, which have to be placed in what would be the first floor ceiling.

As for waterproofing the roof... I have not seen anything being used that makes me confident. The paints/coatings that are more widely used in DR require reapplication within 2 to 3 years. Those products by Xypex seem like they may be a long term solution to what is a very common problem.

There is a sealant that is guaranteed for 5 years. There is also the tar paper system but that can be damaged easily by walking on it.
 

CaptnGlenn

Silver
Mar 29, 2010
2,321
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I have a tile terrace on my rooftop that has to be sealed periodically. It's getting near time to do it again... does anyone know what sealer would be used for that?
 

Chip

Platinum
Jul 25, 2007
16,772
429
0
Santiago
I have a tile terrace on my rooftop that has to be sealed periodically. It's getting near time to do it again... does anyone know what sealer would be used for that?

You could go with a grout sealer and then a standard sealer for the edges if there is no kick plate.