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Leaky Roof In Costa Rica, We Have Your Solution

Mar 29, 2024

How to fix the leaky roofs in Costa Rica

It has been said that approximately eighty-percent of the roofs in Costa Rica leak, and all for basically the same reasons. Most leaks become evident during the rainy season and the locations where the residents discover the leaks on the inside of their dwellings are not where the actual leaks are occurring on top of the roofs.

In Costa Rica there are various types of finished roofing materials installed, and without a doubt, the most common and least expensive are metal laminates, known as “Laminas Onduladas”, in English they are called “Corrugated Laminates”.

When theses metal laminates leak, many homeowners in Costa Rica hire workers, who claim to be experienced roofers, and these guy’s usually climb up on the roof to apply a few tubes of silicone and some aluminum backed adhesive tape to cover the areas where they think the leaks are occurring.

These repair attempts are like applying a band-aid to a serious wound and rarely do they correct the leaks and therefore the building materials inside the attics and ceilings continue to deteriorate from moisture damage, which also causes mold and other health related issues.

Furthermore, while the repair guy’s are walking on the roofs to look for the leaks, they usually dent the metal laminates and then water accumulates in the dents and causes additional problems.

In North America and Europe, the roofs on homes are constructed using significantly more building materials than in Costa Rica. The roof structures in other countries are installed on top of the walls, and then sheathing laminates (such as plywood or OSB boards) are attached to the roof structure to create a flat deck. Then underlayment, (such as black tar paper) that acts as a moisture barrier, is applied to the sheathing to prevent the transfer of moisture inside. Then the finished roofing product, (such as shingles or clay tiles) is attached on top of the underlayment. This type of roof installation lasts for decades without leaks.

However, in Costa Rica, the majority of the roof installations are made with thin metal corrugated laminates attached directly to the roof structure, without a sheathing deck or waterproofing underlayment. These laminates are thin and come in thicknesses of .44mm, .32mm, .27mm and 20mm. Any thickness less than .44 mm is dangerous to walk on and the life expectancy is short, especially near oceans and areas with excessive rainfall and salt air.

In order to attach these laminates to the roof structure, they require at least 12 screws per laminate. These roofing screws have rubber washers to help prevent moisture from entering in the screw holes, but this rubber deteriorates quickly with the strong ultraviolet radiation from the sun in Costa Rica. Once the rubber becomes brittle, the screw perforations are likely to permit water infiltration. On a roof the size of an average home here, there would be approximately 1500 screw holes. You can imagine how much water can enter through this quantity of holes.

Depending on the roof design and the quantity of ridges, hips and valleys, there are many joints, and these areas are where each rectangular metal laminate meets, and this is the source of many roof leaks. In these areas, flat metal laminates, known as “flashings” are cut and installed to prevent moisture from entering underneath, but as with any rectangular building material, the angles and joints are the most difficult to waterproof.

Most homeowners in Costa Rica are accustomed to painting their roof laminates with anti-corrosive paint every year, with the intention of preventing leaks. However, the thin paint does not last long on top of metal laminate roofs less than 12 degrees from the equator, and the roofs continue to leak. But, the painting does conceal rust and makes the laminates look new, so the average home buyer does not think about roof leaks until they hire a home inspector that knows to look for the tell tale signs of water infiltration.

The most reliable method to prevent roof leaks from ever occurring again is to install a flexible membrane material on top the metal laminates, over the flashings and into the valleys and gutters in order to seal the areas where the water infiltration occurs.

The longest lasting solutions are modified bitumen membranes, also referred to as APP or SBS, and they are made from asphalt and a variety of modifiers and solvents. The membranes come in roils that are one meter wide and ten meters long and the most effective method to apply rolls of this material is a heat welding process that adheres the membrane to the surface of the existing roof surface as well as sealing the overlapping rolls together to create a seamless waterproof surface.

The metal roof laminates that are commonly used in Costa Rica are no more than .44 millimeters thick and the new membrane is either 4 or 5 millimeters thick. This additional thickness will provide decades of moisture protection as well as an additional thermal barrier that is very important here in Costa Rica, where we are located so close to the equator. Furthermore, the additional thickness of the new membrane will provide an acoustic barrier to eliminate sound transmission through the roofs and into the inside of the dwellings during heavy rains. When the 4-millimeter thick membrane is installed, it is guaranteed not leak for 8 years and when the 5-millimeter thick membrane is installed, it is guaranteed not to leak for 10 years.

The membrane installation usually takes no more than a few days to a week, depending on the size of the roof. If you have any questions or concerns about this type of waterproofing installation, send a message to the author, Tom Rosenberger. [email protected]

How to fix the leaky roofs in Costa Rica