Costa Rica Construction – Roofing 101

During the rainy season is when you should have done your homework; during the dry season is when you have the opportunity to complete an inspection and make repairs in order to insure that your roofing installation is adequate to protect your dwelling for the rest of the year.

It is prudent to seek the most suitable roofing products, not the most cost effective.

Roofing material components are important. However, the proper installation of the underlayment and flashing are vital to the success of a complete roofing installation.

Some finished roofing products, are basically cosmetic applications, while the majority of the weatherproofing and insulating of the building structure, is accomplished with the underlayment and flashing materials and their proper installation procedures.

The galvanized roofing panels and flashing materials, used here in Costa Rica, require specific dimensions of laminate and flashing overlapping as well as watertight sealants applied between the product overlaps according to the manufacturer’s recommendations.

Here in Costa Rica, over the last 15 years, I have seen driving rains attack roofing installations, vertically and horizontally. The wind blown rain can be forced under roofing laminates and tiles as well as flashing and drip edge installed on the facias of buildings. If adequate underlayment and flashing have not been installed, thousands of dollars of interior installations as well as personal possessions can be damaged.

Most people do not understand that metal laminates respond to temperature change just like wood, by expanding and contracting. This causes the fastener holes size to increase, resulting in leaks. Dark colors will experience the largest thermal movement.

According to the manufacturers of metal roofing laminates, panels installed over Metal Perlin should not harm the roof system with thermal movement. However, I can tell you from personal experience that the manufacturer’s installation recommendations, of attaching the metal laminates directly to a Metal Perlin structure, with screws provided by the manufacturer, still expand, contract and move.

I have seen with my own eyes, two-inch metal screws; unscrew themselves as a result of the metal laminates movement, during one seasonal change.

When selecting a sustainable material for a roof covering in Costa Rica, one should take into account the following variables:

1. Durability- How well can it tolerate the strong ultraviolet rays of the sun and for how long?
2. 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.
3. 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.
4. 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.
5. Weight – Heavier roofing materials will require stronger and more expensive structural materials.
6. 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.
7. 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.
8. 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 specified.

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.
• Fiber-cement composite roof materials are somewhat lighter and use fiber materials resourcefully. Some use waste paper as well as wood fiber. Many have 60-year warranties.

If possible, do not use solid decking with metal roof panels. However if installing over a solid deck, use Z-shaped metal sleepers over the decking. The sleepers will move with the panels and eliminate fatigue where the screws penetrate the panels (the screw hole will become elongated causing leaks) or the screws will lose grip on the decking.

Additionally, the metal panels are on the anodic end of the galvanic scale and can experience galvanic reactions (corrosion), when they come into contact with fasteners and flashings on the cathodic end.

Metal roofing products, with factory applied paint, are manufactured to look like tile.

Factory applied paint performance:

Polyester resin finishes offer least durability and fading will occur in 5 to 7 years.

Silicone modified polyester finishes are superior (the more silicone, the better the performance).

Fluorpolymer resins provide a state of the art finish. Five paint companies produce this paint under the brand names of Duranar, Nubelar, Fluropon, Trinar, and Visulure

Low cost metal roofs, primarily used for agricultural buildings require premium metal coatings such as:

• Zinc (galvanized) coatings oxidize to protect the steel. Protection is lost when the oxidation process uses up the zinc, and the steel underneath can rust. On low-sloped roofs in wet climates, coating loss and rust can show up in five years.
• Aluminum coatings are superior to zinc, carrying warranties up to twenty years. They are inert, and do not degrade over time.
• Aluminum-zinc alloys, or Galvalume, will outperform aluminized coatings and exceed twenty-year warranties.

In conclusion, it is wise to appropriate as much money as necessary to receive the best roof available for your dwelling. If you are purchasing new or existing housing, realize that the roof of that structure is a very important component in protecting your investment and personal possessions as well as your peace of mind.

Written by Tom Rosenberger. With more than 25 years of homebuilding experience, 15 of which have been in Costa Rica, construction consultant Tom Rosenberger knows the ins and outs of building and remodeling a home in the Central Valley area of Costa Rica.

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Andrew Makarik

to@welovecostarica.com

Andrew Makarik is the main editor of WeLoveCostaRica, a fan of this sunny country. He is also a loving husband and a has a lovely daughter. By being a devoted family man and the biggest Costa Rica fan, he wants to make more people feel at home there. WeLoveCostaRica unites people and helps them find new home or a new travel destination. This website is a friendly community where everyone can find not only information, but also new friends and travel pals. Andrew is also passionate about IT and programming, so he himself maintains a friendly atmosphere in this cozy environment of WeLoveCostaRica.com.