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Roofing Systems in Costa Rica Need Careful Consideration

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tropical house roofingHere in Costa Rica, we live in a unique and beautiful environment, with severe climatic characteristics that can be challenging. Our dwellings are exposed to intense ultraviolet rays of the sun, tropical rains that prevail in Central America and the Caribbean, as well as strong winds. Here, construction professionals must carefully consider the most suitable building materials that can withstand these conditions. During my inspections of roofs in Costa Rica over the past 20 years, I’ve observed quite a few different roofing systems and installation methods. Some of the roof products were not correctly matched with the type of roof structure and result in exterior defects and gaps where rainwater enters and causes damage to interior building components. Careful consideration of the various roofing products needs to be matched with the architectural design of the dwelling as well as the positioning of the dwelling in its location. Here in Costa Rica, I’ve seen driving rains attack roofing installations, vertically and horizontally. The windblown rain enters under roofing laminates and tiles as well as flashings. If an adequate roof system and flashings have not been installed, thousands of dollars of interior installations as well as personal possessions can be damaged.

A dwellings roof is one of the most vulnerable components, often times receiving significant damage while protecting everything under it from mother nature. It’s prudent to seek the most suitable roofing products, not the cheapest. Selection of the most suitable roofing components is important, however, proper installation methods and the underlayment decking and flashings are vital to the performance of the selected roofing products. Some finished roofing products, are basically cosmetic applications and the majority of the weatherproofing and insulating of your dwelling is provided by the underlayment decking and flashing materials and these must be installed according to the manufacturer’s proprietary installation methods or water infiltration will occur.

When selecting a sustainable roofing system in Costa Rica, we need to give careful consideration to the following variables:

Durability– How well can it tolerate the strong ultraviolet rays of the sun and for how long?

Heat Resistance– Some roofing materials retain more heat than others do. If the selected product heats up, it will stay hot into the night and can affect the energy efficiency of your dwelling.

Maintainability– Exterior building products here in Costa Rica, less than 10 degrees from the equator, do not perform as well as in other areas that are further away from the equator. A realistic maintenance program should be organized with a knowledgeable builder who has many years of experience here in Costa Rica. Otherwise, when the exterior of your dwelling leaks, it will cause damage to the interior installations as well as your personal items.

Rainwater Effect– Asphalt, Slate, Clay or cementitious materials erode and a portion of the surface aggregate will pass below to other installations and eventually leach into the ground water.

Weight– Heavier roofing materials will require stronger and more expensive structural materials.

Cost– The roof of your dwelling protects all other building materials as well as your personal possessions. You should invest as much as is necessary to install a quality and maintenance free roof.

Fire Rating– Not so much of an issue here as in North America because of federal and local regulations, however your personal safety should always be a consideration when selecting building materials.

Installation Requirements– Once you have selected a roofing product, you should be able to rely on the manufacturers guaranteed performance for many years. Roofing products fail here in Costa Rica because they are not installed according to the manufacturer’s specifications. New products and their proprietary installation techniques are often not understood by the architects who specify them and create the blueprints. It is the responsibility of the builder to install these modern roofing products correctly. Many experienced, Latin tradesmen have been installing traditional roofing materials according to their installation methods for many years but they are not normally receptive to new products and their unique installation methods. You need to be able to communicate well with your builder, and your builder needs to communicate well with the tradesmen who will be installing the materials. Additionally, the builder must be able to speak the language of the tradesmen and have the patience to train them to respect the proprietary installation methods for the products you have selected.

Roofing Material Options:

-Metal roofing materials, such as steel and aluminum, contain high percentages of recycled content, up to 100% in many aluminum products. Most metal roofing, including standing-seam, contains recycled metal. An additional advantage is that these materials are lightweight and durable as well as easily recycled in their post-use.

-Asphalt shingles use recycled, mixed paper in their base and some use reclaimed minerals in the surface aggregate. This type of material does not last as long as others do.

-Recycled plastic roof materials have been introduced as a lightweight option.

-Slate, clay, and cementitious roof materials offer durability and heat resistance, but are heavy and require extensive structural and underlayment waterproofing systems.

Let’s take a look at an upgraded metal laminate product that is popular here in Costa Rica, because it combines the durability of metal with the appearance of traditional tiles. The manufacturers of corrugated roof laminates recommended to install roofing screws through the upper corrugations in order to allow the water to run off and down into the lower portions where it can flow down with gravity and off the laminates. With the height of the upper portion of this type of corrugated laminate, 4 inch screws, with heads in the color to match the laminate will need to be special ordered, because most building suppliers do not stock them. If an installer installs shorter roofing screws into the lower portions of the metal laminates, this can cause leaks, even with the rubber washers under the screw heads. These small rubber washers dry out from the intense ultraviolet rays of the sun and then crack and in these cracks the rainwater can enter under the heads of the screws.

If the screws are installed in the lower grooves, annual review and application of a sealant on every screw head will be required. In the photo below, you can see screws, with a white sealant applied, in the lower grooves of the laminates. My years of experience tells me, that these shorter screws were installed in the lower grooves because the installers did not have longer, (4 inch,) roofing screws to attach the laminates correctly on the upper corrugation. Improper selection of roofing materials and poor installation methods is the main cause of roof leaks in Costa Rica.

Roof laminates should be installed with two channel overlaps on the continuous longitudinal sides, as the ends of the laminates tend to move and open, allowing driving rain to enter under the openings. Sometimes, inexperienced tradesmen install small metal screws on the side overlaps in order to keep the ends of the laminates tight. This is not recommended by the laminate manufacturers and causes problems. Most people and many tradesmen don’t understand that metal laminates respond to temperature change just like wood, by expanding and contracting. This causes the ends of the laminates to buckle up and the fastener holes size to increase, resulting in leaks. Additionally, the installation of screws on the side overlaps of roofing laminates does not allow the laminates to expand and contract, thereby causing the end overlaps to buckle up where one laminate extends beyond the end of the adjoining laminate. As you can see in the photo below, these gaps can open considerably and will allow rainwater to enter under the end overlaps.

If the laminates had been installed correctly, with two channel side overlaps, instead of the one channel overlaps, as in the photo below, the small screws would not have been necessary and the hundreds of additional screws and their holes would not corrode and allow water infiltration. Furthermore, the seasonal installation of expensive sealants and tape would not be necessary to seal the screws heads, holes and gaps on the end and side overlaps.

Following an improper roof installation, inexperienced tradesmen try various methods to repair leaks:

-Sealants applied to the end overlaps of the laminates and ridge caps.

-Sealants and tape applied over holes and under the ridge caps.

-Aluminum backed tape installed over the gap where the laminates meet on the ridges.

-Screws installed into the loose side overlaps of the laminates

Most sealant products and tape are not durable enough to withstand more than one summer of the intense ultraviolet rays of the sun in Costa Rica and seasonal review and/or re-installation will be necessary.

This tape helps to keep rainwater from entering holes and under the gaps where the ridge caps meet the roof laminates. However, the installation of this tape is like putting a bandaid on a serious wound that needs surgery.

In the large gaps between the laminates and the ridge caps, as is detailed in the photo below; moisture, insects and rodents can enter in these openings. These large gaps are a result of the high profile of this type of roofing system. Once these laminates and their accessories have been installed, the only alternative to prevent infiltration is to fill the gaps with an expansive foam product and then paint the foam to match the roof color. I recommend Sista products that are specially fabricated for roofing applications. The Sista foam expands when applied, adheres well on metal, is resistant to temperature changes and can be painted to match the existing colors of the exterior surfaces. Before sealing all existing open gaps, ventilation of the ceiling and soffit cavities will need to be considered. Again, if a more suitable roofing system and better trained installers were selected, these problems would not burden the homeowner with the maintenance and expense that will be required annually.

Another problem when selecting high profile corrugated laminates is that the ends of the laminates need to be cut with a metal cutting disk on a grinder. Most metal laminate manufacturers do not recommend cutting with any type of abrasive metal blade, because it allows for abrasions on the edges where corrosion begins. A circular saw with a carbide metal cutting blade is recommended. However, the installers need to be careful when using a cutting blade on a circular saw, because the saw guides will undoubtedly scratch the exterior surface, where corrosion will begin. It is recommended to cut on the underside of the laminates in order to avoid scratching the exterior surface. This method takes additional time and labor and therefore most installers take the path of least resistance and the owner of the dwelling ends up footing the bill for the necessary repairs and continual maintenance.

In the photo above, you can see quality metal valley flashing that was custom made to prevent leaks in the valleys. Additionally, in the photo below, you can see good quality metal edge flashing that was installed where the edge of the roof meets the gutters, and it was also custom made to prevent leaks behind the gutters on the fascias. Because quality flashing materials are not available in most local building supply locations, they need to be specified and custom made by a specialty shop and that takes planning and waiting for fabrication of the flashing pieces. Most installers don’t have the patience or the ability to plan ahead, and therefore, the installation gets completed with incorrect fasteners and flashing materials.

Because, the metal roof laminates are attached directly to most roof structures, with any decking or waterproofing underlayment, a roof installation completed with improper installation methods and inadequate materials will leak into the ceilings and attics of dwellings when it rains hard. The rain will enter under the gaps on the end overlaps of the roofing laminates and under the loose screw heads where the rubber washers have dried out and cracked. The easiest alternative is to fill these gaps with a sealant like Duretan, which is available in colors to match the roof laminates. Seasonal revision and re-installation of the sealants and tape will be necessary to prevent further leaks. I recommend that a small and light person install the sealants and that the installer wear rubber soled shoes and know to walk only where the roof structure supports are located, so as not to cause dents on top of the laminates where moisture will accumulate.

If you build a home and cut corners on the roof installation or if you purchase a home that has a problematic roof, you will need annual revisions and re-installation of exterior sealants and materials that deteriorate from the intense ultraviolet rays of the sun in Costa Rica. If the exterior surfaces are allowed to deteriorate for an extended period of time, you will encounter damage to interior building components.

In conclusion, it’s wise to appropriate as much money as necessary to receive the best roof available for your dwelling. When purchasing new or existing dwellings, keep in mind that the roof is one of the most important components to protect your investment, personal possessions and peace of mind.

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