Do it yourself: Sealing up concrete, stone and ceramics

Do it yourself: Sealing up concrete, stone and ceramics


Sealant products. Jet Odrerir

Even when a flat roof or balcony looks in good shape, there can be many ways for water to find its way ever downward.

If you want to seal a flat roof, there are two ways of doing it: using an overcoat or using an impregnating sealer.

Most flat roofs in Cambodia have been kept going by using bituminous sealants, which is a fancy way of saying tar mixed with fine particles. But you do not want it on your place.

It's black, attracts heat and UV rays and doesn't last more than a couple of years. You end up with a hot, cracked, leaky roof, right back where you started.

An overcoat is a thick liquid similar to paint that will expand and contract with the weather and act like a membrane for your roof. It is not a new roof, simply a covering for what you have. The flaws need to be repaired and the roof structurally sound.

Boscoseal is a white polyurethane overcoat sold at Botica. Modern roof coatings are lighter in color to deflect sunlight. Take your roof measurements to the store, and they will work out how much sealant you need. You will need a paint pan - a 20-liter water jug cut in half works well - a large paintbrush, a paint roller with an extension rod, disposable gloves, rags, a bucket of water and a utility knife and screwdriver for opening the buckets.

Wash the roof thoroughly. Spray or mop off all silt and other debris. Rinse the entire area, as detergents will resist the sealant's adhesion.

When the roof is dry, begin at the outer edges by painting up any vertical surfaces about 30 cm, making sure all corners are coated. After a 10-square-metre area has been cut in, roll out the flat area. Don't let the sealant pool heavily in any areas, as these may crack when drying. Continue until the entire roof is coated. Come back the next day and look for imperfections, which can usually be fixed with a swab of the paintbrush.

These types of rubberized roof sealants will typically last 5-10 years with no foot traffic.

Impregnating sealants work by soaking into the concrete or tile and filling in the gaps.

A couple of very good products, Sikagard 700s and Protectosil, have made their way here recently. These can be used on concrete, tile and stone.

Sikagard 700S is similar in appearance to paint thinner. It is applied by brush to a clean surface, and after two or three applications the surface will be impenetrable to water. It causes discolouration, so you shouldn't use it where it'll be seen.

Protectosil definitely gets a top rating. It comes in a concentrate and is thinned out with water. Apply two coats and you're done. It's very easy to use and doesn't cause discolouration. The owner of Botica said that it had been used to waterproof Angkor Wat. I'd call that a seal of approval.

Sika products can be purchased at Lim Huy Seam, 120 Street 432.

Protectosil and Boscoseal can be purchased at Botica, 249 Mao Tse Toung Boulevard.


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