Most people who move to Costa Rica and decide to rent or purchase housing, don’t understand the differences between North American and Costa Rican Roofing Standards until they’ve had a chance to live here for a while and experience firsthand the ramifications of the local construction methods.
Costa Rica is located between nine and twelve degrees north of the equator and the intense ultraviolet radiation and strong rains cause exterior roofing products to deteriorate prematurely and the subsequent water infiltration that occurs in gaps between roofing laminates, where contraction and expansion occurs, enters inside dwellings and causes moisture-related problems.
I’ve been building and inspecting housing in Costa Rica since 1993 and from this constant exposure to construction materials and different installation methods, I can tell you that 90% of the dwellings I’ve inspected have roofing problems that allow water infiltration to enter inside the dwellings under roofing laminates and flashing materials. Depending on the construction materials that were used to construct the roof, there are a variety of problems and solutions that I will address.
Here in Costa Rica, even with expensive housing, there’s usually no insulation, solid sheathing products or waterproofing underlayment materials installed under the finished roof surfaces. Without sheathing or a waterproofing underlayment installed between the roof and the interior ceilings, the infiltration of water can end up in the attic or on the interior ceilings. Initially, this moisture causes damage to the building materials in the form of mold and mildew. After a period of time, the moisture damage graduates into building materials deterioration and then replacement becomes necessary.
To better understand Costa Rican Roofing Standards, the following illustrations detail the construction of most homes in Costa Rica.
The roof structure is of lightweight wood or metal that was not designed to support the weight of quality roofing components.
To save money, thin metal laminates are screwed directly into the roof structure without any insulation, sheathing or waterproofing underlayment products under the finished roof surface.
Since many homes have open ceilings, there is no attic or insulated space to defer the heat transfer from the high levels of ultraviolet radiation from being less than twelve degrees from the equator.
The most common interior ceiling materials specified by the local architects are wood strips
or drywall laminates that are attached to the underside of the roof structure.
There’s very little space between the finished roof surface and the interior ceilings, so it is nearly impossible to install conventional insulation. Additionally, wood and drywall absorb moisture, and moisture enters into interior living areas via two paths:
- The space between the roof laminates and the interior ceilings is not airtight and exterior moisture penetrates inside. Night, sky radiation causes the trapped humid air in the space between the ceilings and finished roof surface to diffuse into the ceilings.
- The roof becomes damp during the evenings, because of night-sky radiation and subsequently, condensation infiltrates into the ceilings by intense ultraviolet radiation the next day.
Both paths result in moisture accumulation and the condensation on the underside of the finished roof surface will be absorbed by the wood or drywall ceilings.
Additionally, wood and drywall contain cellulose materials that are food sources for wood eating insects, mold, and mildew. With the daily condensation produced in the space below the roof laminates and above the interior ceilings, this will become a problem that will not go away without removal and replacement of all the ceilings.
If the owners are not living in Costa Rica while their new home is being constructed, and they do not understand the ramifications of this less expensive, lightweight roofing method, once they make the final payment to the building contractor, they will have no choice except to live with the consequences.
I have inspected many homes here for clients that have read some of my construction related articles published in the Tico Times and Costa Rica Star. When I find defects as described above, I usually recommended that the purchasers ask the owner or the architect that designed the home to explain why the roof installation does not include insulation, sheathing or a waterproof underlayment to prevent heat and moisture from passing into the interior living areas.
The purchasers many times are told by the owner or architect not to worry, and that the roof was designed and constructed according to Costa Rican Roofing Standards.
Now that you understand a little more about the Costa Rican Roofing Standards, let’s take a look at the basic components of a quality roof designed to North American standards.
In North America, the roofs on homes are normally constructed with all the components detailed in these two diagrams.
The roof structure is installed on top of the main beam of the wall columns, and then sheathing laminates, such as plywood or cementitious laminates are attached to the roof structure to create a flat deck. Then an underlayment product, such as black tar paper or a waterproofing membrane is applied to the sheathing to prevent the transfer of moisture inside. Ultimately, the finished roof covering, such as shingles, clay tiles or metal laminates are installed on top of the underlayment.
With this type of quality construction, a roof can be guaranteed not to leak and the interior living areas will maintain a healthy level of humidity and a temperature that is comfortable for the homeowners.
The writer, Tom Rosenberger has lived and worked in Costa Rica since 1993, inspecting land and housing for people who want to purchase existing homes or build new construction here.
In addition to Standard Home Inspections, since some people who are building new homes cannot be in Costa Rica while their new homes are under construction, Tom provides Construction Progress Inspections for monitoring the quality during all phases of the home building process. With Tom’s detailed inspection reports, the homeowner can be confident that their dream home will be everything they imagined.
You can review a Construction Progress Inspection Report by clicking here.
If you would like to schedule a consultation or home inspection you can click here.