The demands of a tropical climate dictate different considerations when choosing a roofing material for your home: Factors that may or may not play a significant role in roofing in a different climate can make a big difference in a tropical situation. Here are some things to consider when choosing a material for your roof:
Slate is naturally fireproof, and its low (less than 0.4%) water absorption index makes it virtually waterproof. This also makes it a material that doesn’t favor the growth of algae. Choosing a light-colored or earth-toned slate increases your roof’s ability to reflect radiant light. Coupled with slate’s high thermal mass, this reduces the amount of heat absorbed into your home. Slate’s high durability and low maintenance requirements make it a good, high-end roofing material.
The main downside to slate, aside from the expense, is the weight: not all homes can support the weight of a slate roof.
Clay and Terra Cotta
Clay and terra cotta are similar enough that considerations pertaining to one carry over to the other. Both materials have good thermal mass. When combined with modern “cool” paint colors they are very good at keeping a home cool by reflecting back radiant heat.
One important consideration when choosing clay or terra cotta tiles is their shape: the half-barrel or “S” shape tile allows both water and air to flow freely below the tiles. The free passage of air beneath the arch of the tiles prevents heat capture and keeps the area below (i.e., your home) cooler.
As with slate, the main disadvantage to clay and terra cotta tile is the weight: the tiles are heavy and require a solid foundation on which they can be installed.
Concrete is generally less expensive than slate or clay, and comes with many of the same considerations. It is heavy and requires a strong support. Its high thermal mass, when combined with a cool color, gives it good reflectivity and makes an effective cool roof. The main difference is that, while concrete is available in tile form, it is also available as poured concrete. Such concrete slab roofing is a common, low-cost option in many developing countries, providing good protection from both pests and bad weather.
Metal roofing’s main advantages are its durability and low maintenance. It is also generally lighter than any of the other tile materials, which makes it good for situations where the house cannot otherwise support a tile roof.
Metal heats up very quickly, but loses heat much faster than tile. When painted white, it reflects more heat than a similarly white-painted clay or concrete roof. Proper installation is also a consideration: if the roof is not properly constructed with considerations for the slope and glare, it will reflect heat and light on nearby residents.
In Part III, coming soon, we will discuss non-traditional approaches to roofing in tropical climates.