It is there above us, protecting us from sun, wind, and rain; however; generally we don’t think about our roof until we see water leaking through it. Typically, roofs here at Lake Chapala are constructed using the boveda construction technique where red bricks are arched between steel beams and the top or exterior is capped with a mixture of mortar and concrete. The basic roof structure is then typically covered with a flat tile and sometimes if the roof is inclined, overlaid with traditional rounded red tiles, which overlap each other to cover the roof surface.
The rounded tiles are generally decorative, since alone the porous tiles will allow water to filter through. However, these tiles do help the roof pitch the rainwater away from the roof surface below, and of course provide solar protection to this waterproofed roof surface.
The key element for waterproofing a roof surface is the final layer at the top of the roof structure. Typically, this surface is painted with an impermeable paint or roof coating to prevent water from entering the roof structure. These paints are typically elastic and resistant to the small movements of the roof structure and will fill in any cracks in the roof surface. Some roof-sealing products work with a fibrous cloth, which acts as a reinforcing medium for the sealant to help the roof sealant resist the future formation of small cracks on the roof surface. Other roof-sealant products have different recipes of ingredients, which will help the roof sealant resist deterioration caused by the ultraviolet and infrared rays of the sun. Also, the various sealants will have different guarantees as to the durability of the product, usually claiming to last anywhere from one to five years.
Some homes have flat roofs, a euphemism since they are typically not perfectly flat. If they were, the rainwater would not easily flow off the roof. Typically the roof surface is pitched towards a central roof drain or a drain along the edge of the roof. These types of roofs will also have a parapet of varying height around the perimeter of the roof. Usually, an interior corner filler is installed (where the interior of the parapet and roof meet) to help water pitch from the parapet towards the center of the roof rather than settle into this same corner. A primary concern on these flat roofs is to prevent any puddling of water on the roof, which would allow the water to have time to find a small crack and enter the roof structure. Care should be taken during construction to assure that roofs pitch towards any given drain on the roof. The quality of these details will determine the long-term ability of the roof to shed rainwater quickly and avoid roof leaks.
The best way for the homeowner to prevent leaks is to check his roof before during and after the rainy season. Before the rainy season the homeowner should thoroughly examine the surface of the flat roof looking for loose or bubbled-up roof sealant and small cracks. On inclined roof areas with round roof tiles, one should check to see that all roof tiles are sitting correctly and have not been damaged or moved. The loose material on the flat roofs should be removed and individual spots and small cracks resealed with an appropriate roof-sealing product. Also any debris on the roof and, in particular, accumulating at the openings of roof drains, should be removed. Similarly, the roof should be reviewed during the rainy season to assure that the drains are free of debris and free-flowing. Any puddling can be detected at this time. Puddling does not guarantee a leak but it certainly gives water time to find an outlet and create a leak.
And finally, the roof should be reappraised after the rainy season. The rainy season is the best time to prove a roof and minor repairs can be done where necessary. It need not be an unpleasant surprise when a rare winter storm comes along and dumps heavy rainfall. Be prepared and the sound of rain on your roof can be a pleasant one.
Brad is a Professional Civil Engineer and has lived and worked in Lake Chapala for more than 11 years. He is the sole proprietor of Ajijic Home Inspections.
