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 construction standards until they’ve had a chance to live here for a while and experience firsthand the ramifications of the local construction standards.
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 for 23 years and from this constant exposure to construction materials and different installation methods, I can tell you that ninety-five percent of the dwellings I’ve inspected have roofing problems that allow water infiltration under roofing laminates and inside the dwellings. 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 insulating or waterproofing materials installed under the finished roof surfaces. Without a waterproofing layer 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 construction standards, the following illustrations detail the construction of a high-end home in a new subdivision in Costa Rica during 2015. The roof structure is of lightweight metal tubes that were not designed to support the weight of quality roofing components.
To save money, thin metal roof laminates are screwed directly into the metal structure without any insulation or waterproofing products under the finished roof surface.
Since this is an open ceiling design, 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 interior ceiling material specified by the architect is drywall that is attached to the underside of the metal roof structure.
There’s very little space between the metal roof laminates and the interior drywall ceilings, so there is no way to install insulation. Additionally, drywall absorbs 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 outdoor moisture penetrates inside. Night, sky radiation causes the trapped humid air in the space between the ceilings and roof laminates to diffuse into the drywall ceilings.
- The roof becomes damp during the evenings, because of night-sky radiation and subsequently, condensation infiltrates into the drywall by intense ultraviolet radiation the next day.
Both paths result in moisture accumulation and the condensation on the underside of the metal roof laminates will be absorbed by the drywall ceilings. Drywall contains the plant material cellulose and this is a food source for termites, 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 drywall ceilings.
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 construction method. Once they make the final payment to the building contractor, they will have no choice except to live with the consequences.
I was not the construction inspector for the homeowners of this project, but they had read some of my construction related articles published in the Tico Times and they reached out to me about some concerns they had. I recommended that they ask their architect to upgrade the roof installation during the preliminary phase of construction, in order to add insulation and a waterproof barrier to prevent heat and moisture from passing into the interior living areas. This way, if the homeowners decide to air condition their new home, the electricity costs won’t break their budget.
The owners were told by their architect not to worry, and he assured them that their roof was designed and being constructed according to Costa Rican construction standards. When the homeowners asked him, “how can a roof with no insulation or a waterproofing layer underneath be acceptable construction standards for a new luxury home?” The architect told them, “That’s the way we do it in Costa Rica.”
Now that you are able to understand a little more about Costa Rican construction standards, let’s take a look at the 12 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 another waterproofing product) acts as a moisture barrier and 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 for 24 years, inspecting land, homes, and condominiums for people who want to purchase existing property or build new construction.
Since some people 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.