The roof of a house is typically the most exposed to solar radiation. Therefore, choosing the right roof in hot tropical climates is essential to minimise the heat coming into your home.
A roof is an essential part of a house or building. In the tropics, places of shelter can get away without having windows, doors, walls or even a floor. However, a roof is essential for providing shade from the sun and protection from the rain.
As such, it must perform well in its climate. Apart from a roof’s resilience to hurricanes, you should choose a design that minimises solar heat exposure. In addition, since many tropical regions receive a lot of rainfall, it is good to have a roof that performs well in this type of weather.
Here are some things to consider when choosing a roof for your home in a tropical climate
Roofs can come in many shapes, styles and sizes. Their properties determine how well they perform in tropical climates.
Flat roofs are a popular element of a modern contemporary home. They tie in well with a clean, minimalist look of Modernism.
These are not perfectly flat and do have some slope to ensure rainwater can drain off. However, this slope is sometimes not enough for torrential rainwater to flow off fast enough. In tropical regions with significant rain during the monsoon season, flat roofs can sometimes encourage ponding and risk potential failure to leak.
Hence, flat roofs are more suited for climates that do not receive a lot of rainfall.
In addition, they can often end up being lower than pitched roofs. Therefore, heat that may accumulate under the roof level is lower. Hence, closer to your space.
Roofs that have one or more sloping surfaces are called pitched roofs. The pitch angle may vary depending on the style, performance or even its resistance to high winds.
Pitched roofs are more popular in tropical regions. They are found in both traditional and tropical contemporary homes.
They are several types of pitched roofs. Some of the more popular styles in tropical regions include shed or lean-to, gable and hip roofs.
Like the degree of pitch, the different types of roofs also perform in various ways to your home’s function, style, and appearance.
Shed Roofs or Lean-To Roofs have one sloping surface usually attached to one low wall and one high wall. They are simple to construct. Hence, they are also generally cheaper than other pitched roofs. Because of the one tall wall on the high side of the roof, lean-to roofs can also carry high-level windows for venting the roof space. Lean-to roofs are suitable for shedding water but can have problems in high winds.
A lean-to may be a bit more unique and provide a more contemporary expression.
Gable Roofs have two sloping sides. The walls on both ends create a characteristic triangular form. They are popular in many regions and hence can give a more traditional look to your home. The high ceilings in the middle of a gable roof provide a space for hot rising air far from you and your family below. The gable end walls also provide space to install a vent to let that hot air escape.
Hip Roofs are also admired and, on their own, can feel quite traditional. They have four sloping sides, which them the best resistance to high winds of the three roofs mentioned. However, hip roofs are a little harder to vent. Since they do not have any high-level walls, it means installing vents on the roof. These vents can be a potential area for leaks if not correctly installed.
Residential roofs usually come in two main types of construction. They are concrete and framed construction.
Concrete roofs, as their name implies, are made from concrete. This type of construction could either be precast concrete or in-situ (or cast-in-place) concrete.
In-situ concrete is perhaps more popular in residential applications than precast. It consists of creating formwork, platting steel rebar and pouring concrete into the formwork. The process of pouring concrete means that these roof slabs tend to be generally flat. Hence, they are susceptible to the concerns raised earlier with flat roofs in regions with high rainfall.
Therefore, flat concrete roofs need to ensure adequate falls to drains. They also need to go through a careful waterproofing process.
In addition, concrete is a high thermal massing material. This property means that it absorbs heat, stores it and releases it slowly when the heat source is gone.
Since your home’s roof receives a lot of sunshine, it absorbs its heat during the day. Hence, at night that heat radiates into your home, making your interior temperature warmer. This heat is not ideal for hot, humid climates since nights can still be warm. Therefore, at night when you close all the windows in your home, this can help make your interior temperature uncomfortable.
However, concrete roofs are widespread in tropical regions because of their natural resistance to severe hurricane-force winds.
A framed roof structure typically consists of timber or metal framing members. These could be individual members like rafters and purlins, or they could be trusses.
Trusses are prefabricated structural framing systems. They tend to be stronger, especially in wider spans. In addition, building them in factories means there is better quality control. On-site assembly time is also a lot shorter than rafters.
If you are thinking of using your ceiling space for extra storage, trusses can sometimes hinder this. Their webbing members reduce the area as opposed to rafters.
For open ceilings, a well-designed truss can create an exciting look and character for your home.
According to the size of the truss, getting them delivered to the site can sometimes be a challenge.
Rafters usually consist of inclined wood members. They span from wall to wall, in lean-to roofs, or from wall to a ridge board. A builder assembles the rafters on site. As such, they take more time on-site to construct.
The clear open area created by rafters also makes them suitable for adding storage to your ceiling space. You also have more room to develop unique ceilings like trays or vaults.
Both methods are effective, and depending on your region, either one may be more popular. However, the one you choose will depend on your specific application and your preference.
The roof covering is the covering material that goes over the framing or decking of the roof. Since it is the upper layer, it is usually the most exposed to the rain and sun of the tropics.
They are several types of roofs covering materials that come in many styles. Hence, they impact the appearance of your home while protecting you from the elements.
Here are a few popular roof coverings that perform well in tropical regions.
Metal roofs are popular in tropical regions. They are durable, cost-effective and resistant to the harsh weather conditions of the tropics.
In addition, they are naturally water-resistant and often do not require an additional water barrier like some other coverings.
Also, metal heats up and transfers heat quickly. However, metal also cools down quickly and would not store and release heat like a concrete roof slab.
Metal roof coverings come in different materials including galvanised steel, aluminium and copper. Also, they come in several colours, styles and shapes. These include corrugated or profile sheets, standing-seam and other types of panels.
However, keep in mind that metals can rust or corrode. Hence, be careful when choosing metal roofs in coastal with high sea spray.
Terracotta clay tiles are also popular in tropical and subtropical regions. Their distinctive colour gives them a striking and beautiful appearance.
They are durable and has a long lifespan. In addition, clay, which is a natural material, makes terracotta roof tiles. Hence, these roof tiles offer some environmental benefits.
However, clay tiles are not naturally weathertight and need an underlayment layer. In addition, they are also heavier than some other roof coverings. This additional weight means that the roof framing structure may need to be stronger than lighter roof coverings like metal.
Shingles are individual elements, similar to tiles, that overlap to form a covering. They come in different materials. These include asphalt, wood, metal and plastic.
Like tiles, shingles typically require a waterproofing underlay. Shingles are often susceptible to strong winds like in a storm or hurricane. Individual pieces can blow off in high winds. However, the roof remains weathertight.
Though not as widely used as some of the other shingles or roof coverings previously mentioned, solar shingles are gaining popularity. Solar shingles are essentially photovoltaic panels made to look like regular roofing shingles. They are part of a trend that seeks to replace traditional building materials with specially designed photovoltaic components.
They harness solar energy from the sun and convert it into electrical energy.
Companies such as Tesla have made significant progress in the performance and appearance of solar roof tiles. We can expect to see growth and development in this trend as the world incorporates more renewable energy sources into our homes and buildings.
Natural roof covering materials like thatch and grass became unpopular in contemporary tropical residential architecture decades ago.
Such materials performed well in their tropical climates. They used locally sourced materials with very little to no manufacturing process. Perhaps these properties made them more sustainable than any other product out there on the market. However, they do have the potential to leak.
In addition, natural roof coverings like thatch have excellent insulating properties and are breathable.
Even though this roof covering is not popular in modern-day residential applications, tropical resorts use it often.
I am not suggesting you build your roof from thatch like old vernacular homes. However, I sometimes wonder if we shouldn’t create homes more like the tropical resorts we see and want to visit. The design of these resorts promotes all the best elements of living in a tropical paradise. They open to natural breezes, views and lush tropical vegetation.
Green or living roofs provide a space for trees, plants and other vegetation to grow. They are becoming more popular, especially in urban areas. In these areas, there is not a lot of room for green spaces around your home. Hence, the roof area provides an excellent opportunity to get back some green area used by the building.
In addition, they are also better for the environment. These roofs retain more stormwater for plants and trees rather than going into a stormwater management system. Roof gardens can also provide insulation to the rooms below, while the plants or trees provide shade.
Photo: Hiroyuki Oki | Thang House | VTN Architects
Also, a lush green garden on your roof can significantly enhance the appearance of your home. They also provide a great outdoor space for you to enjoy.
However, you should design these carefully and build them to ensure they do not leak.
Lighter colours are better in the tropics. Light colours like white, light grey or similar absorb less heat than darker colours.
It is best to minimise the amount of heat absorbed by your rooftop. The roof with dark colour intensifies and transfers that heat to the inside.
Another way of reducing the heat in your roof is by using a reflective surface. Reflective finishes help reduce the heat it absorbs.
Heat can build up under a roof. This heat can accumulate from transfer from the top above or rising warm air in the room.
Having high pitched roofs help keep the warm air high above the people below.
In addition, roofs with a steep pitch allow rainwater to fall off more quickly. This slope reduces the chance of leaks that can sometimes occur in flat or low pitched roofs.
Providing a means of venting your roof is good in the tropics. Hot air rises. As it rises, it finds the uppermost part of your home.
Having a place for that heat to escape allows cooler air to enter.
Some roof types are more accessible to accommodate ventilation. As previously stated, lean-to roofs can have a high level of clerestory windows on the high wall.
Similarly, gable roofs can have louvres or windows to vent that area. This practice was prevalent in traditional architecture, including the chattel house in Barbados.
Allowing hot air to get out at the rooftop level is something I don’t see often enough.
Double roofs are a way to reduce the heat that impacts a roof significantly.
Photo: Ketsiree Wongwan | P24 House | OFFICE AT
With double roofs, they comprise two layers. They can consist of two similar types or two utterly different roof systems.
How it works is that the upper roof layer receives the intense impact of the sun. There is usually an air space between the two layers. This space allows hot air to dissipate while protecting the second roof layer below.
The roof is such a critical element of a home. Its style, shape and design have a significant influence on the character of your home.
You need to consider so many things. Its durability, resilience and aesthetics are among some of these considerations.
If you are focussing on creating the ideal roof for your home that responds to the hot, wet climate tropics, here are a few things to consider.
Thermally, a high pitched roof will help protect the liveable spaces below from the heat. Rising hot air or hot air transmitted through the roof will be a safe distance from you. In addition, flat roofs are not ideal where there is a lot of rainfall. Though these roofs can be sloped to drain correctly, flat roofs may have difficulty shedding water quickly. Pitched roofs do not usually have this problem.
A framed roof with lightweight roof coverings will not absorb heat as a concrete roof would. Concrete roofs may be naturally stronger in intense hurricanes, but they store heat and releases it into your home at night.
With so many options for roof coverings out there, many come with subtle pros and cons. Metal is durable and cools quickly. They are cost-effective and provide a weathertight barrier on their own. These factors make them a viable option for the tropics.
However, emerging trends in solar shingles and green roofs make these options worth considering.
Always go for lighter colours over dark ones. Also, use reflective finishes where possible to help reduce the heat the roof absorbs or transfers.
Incorporating a double roof system keeps the heat off your lower roof and your home’s interior by extension. In addition, they are benefits to adding vents or windows at roof level to allow hot air to escape.
Be sure to consider these and all other factors that will influence the best roof design for your home.
Featured image by Tirachard Kumtanom from Pexels
Find out all the major principles of designing a house in the tropics.
Or explore more of the other topics in this series.
Site Orientation: The orientation of your home on its site dictates how well it responds to passive design principles.
Shading Strategies: Reducing the solar heat gain in your home can create a better thermally comfortable home.
Passive Ventilation: Natural or passive ventilation is one of the primary concerns of a tropical home.
Wall Materials and Construction: In hot, humid climates, your wall materials need to perform various functions.
Roof Design: Choosing the right roof in hot tropical climates is essential to minimize heat gain.
Exterior Spaces: Making outdoor spaces and nature part of tropical homes is ideal.
Water and Energy Efficiency: With climate change, renewable energy and water resource management are crucial.
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