Best Roofing Practices and Materials for the Caribbean
When designing your project, an obviously important element of the build is the material choose and installation methods of the roof.
When building with materials and styles outside of the norms of a given region, costs quickly rise. The Caribbean is generally a very expensive place to build, and finding the right balance between keeping costs down, storm resistance, and longevity is key to helping your investment pay off.
Skills and Expertise Required for Installation
Another significant consideration is the workforce available for installation for specialty and uncommon building features and materials. In many countries in the Caribbean, current builders began their careers at a time when corrugated galvanised steel ‘tin’ roofs was the typical material of choice for the average home. Skill sets and abilities in the Caribbean continue to evolve and expand, yet on many of the smaller islands, it’s necessary to bring in skilled expertise and equipment for installation of specialty elements.
A primary consideration of building design and material selection, especially as it pertains to roofing, is hurricane resistance.
An excellent and practical case study is the island of Providenciales in the Turks and Caicos, and how structures were impacted by Hurricane Irma and Hurricane Maria in 2017. Providenciales has experienced a more accelerated pace of development than nearly any other island in the region, with the vast majority of structures having been built in the last 20 years. Many roofing types were represented on the island, with varying levels of build quality. In the days following the major storms, it was remarkable how nearly every properly-installed metal standing seam roof withstood the hurricanes, and the majority of roofs finished with asphalt shingles, wood shingles, or tiles had damage that required repairs or full roof replacement.
The US government Federal Emergency Management Agency (FEMA) conducted extensive studies on roofing storm resistance, and their findings and recommended best practices are certainly apt for the Caribbean.
Corrosion in a Marine Environment
Rust and corrosion is a significant concern in the Caribbean. Steel, zinc alloys, and some of the simpler aluminium alloys (often used in lower-cost window and door frame extrusions) will inevitably decay, often within a decade or two of installation. Stainless steel, hot dipped galvanised steel that is not directly exposed to the elements, and some of the more corrosion resistant aluminium alloys (such as variants of the 5000 series) will last a lifetime.
Stainless steels are available in a wide array of alloys. Unless closely exposed to the ocean, all common alloys will generally remain structurally strong for a very long time, yet less-expensive alloys may experience light surface rust or staining.
Today, it’s possible to find corrosion and rust resistant alloys and coatings for all elements where metal is utilized on roofs. Initial item cost is of course higher, yet proper fastener choice reduces maintenance and staining, and largely eliminates premature failure.
Drip edge corrosion is also a consideration. Stainless steel, copper, and aluminium materials are available, and are far preferable to the common galvanised steel and PVC varieties.
Another consideration is galvanic corrosion, most commonly experienced in the residential setting in situations where steel and aluminium contact.
Important Installation Considerations
One area that is very important and must be monitored during construction is the selection of fasteners and adhesives used to secure the roofing. Material manufacturers typically provide detailed installation instructions, yet regional contractors all too often ignore such recommendations, which can lead to premature failure of the system. Good quality peel and stick type adhesive membrane water and ice shields are important, as well.
Screw and nail materials and lengths are also critical to longevity, and common practices in the Caribbean are to default to the widely-available basic nails and screws that are either electroplated or hot dipped galvanized, and are often too short for the application. Typically, the added cost of properly sized stainless fasteners is well worth it. In most residential cases, the best practice is to use the longest (within reason) stainless fastener that the substrate allows.
Roofing technologies such as metal standing seam or some modern tile systems that rely on metal brackets is a similar situation. Unless specified otherwise, most builders will choose the least expensive option, as opposed to the better larger gauge options in the most corrosion resistant materials. The added cost of the better materials is often well worth the long term benefits.
Working with experienced and competent project managers helps to ensure that the details are done right.
Common Roof Material Types
Choosing a roofing style and material is a balancing act between cost, appearance, longevity, and durability.
Another consideration to keep in mind is if rainwater collected from the roof will be used. Some types roofing, and the installation techniques use for asphalt, wood, and other types of roofing may have higher pollutants and contaminants.
Metal Standing Seam
Metal (typically aluminium) standing seam had become the most popular roofing choice for mid and higher quality construction in the Turks and Caicos and much of the Caribbean. There are several reasons for this, yet durability and lifespan are foremost.
Standing seam is a sheet metal roofing system that interlocks together, and has no visible fasteners when finished. This type of roofing is typically shipped as a spool of rolled sheet metal, which is then formed into the chosen profile at or near the building site with a special rollforming machine. Brackets and screws are used to anchor the standing seam metal.
Standing seam roofing is available in a spectrum of colours and alloys, with gloss white coated aluminium being the leading choice.
It’s often the best practice to select one of the heavier metal gauges over the widely-used thinner gauges for increased hurricane resistance.
A standing seam roof that’s properly installed could likely outlast the lifecycle of the structure, as long it doesn’t experience impact damage from flying debris during a hurricane. This type of roofing also costs less to maintain than most other roofing types, and typically doesn’t require much cleaning or mildew removal.
The relatively inexpensive and ubiquitous asphalt shingle is one of the most common roof choices in the Caribbean, simply due to the low material and installation costs.
Products range from the basic 3 tab rectangle design to stylised ‘architectural’ types, with various wind classes of wind resistance.
When installed properly with adhesive and appropriate length nails, mid to higher quality asphalt shingles can be surprisingly storm resistant, yet the loss of a few shingle faces is almost inevitable during high wind speeds, which then often dictates roof replacement. It’s critical that manufacturer guidelines are followed during installation, especially in regards to the starter strip, and the hips, ridges, and rakes.
Clay and concrete tiles have traditionally been a favoured roofing choose for better-quality structures in the Caribbean for centuries, yet today may not be the best choice as they are comparatively expensive and are not particularly storm resistant. Often, these designs are chosen primarily for their appearance.
Tile roofs can be installed in several different ways, including with nails or screws, wire, brackets, or with mortar. As with other roofing types, the corrosion resistance and length of fasteners used is critical for durability.
Another consideration is that when roofing tiles do come loose during major storms, they can become dangerous projectiles, and can cause additional damage to property.
Reinforced poured concrete roofs often have a poor reputation as they often considered “problematic”, yet almost all issues are derived from poor construction techniques and inappropriate material selection.
The fact is that the primarily downside to a properly constructed concrete roofs is initial cost. They tend to have excellent storm resistance, and lifespan, let more so than other designs, they have to be done right.
Concrete roofs may be flat or slopped, and are typically sealed with coatings that may include epoxies, elastomerics, and cement-based coatings.
Ondura and Corrugated Asphalt Roofs
Ondura (the most common brand) and equivalent products made by other manufacturers are corrugated asphalt roofing sheets. The product is produced in a variety of colours, and is quite popular in the Caribbean. It tends to be inexpensive, and when installed right, withstands high wind speeds relatively well.
Wood shingles and other primarily organic materials, much like clay tile, offer poor performance and high cost. Storm resistance is often inadequate, lifespan may be short, and roof water often isn’t suitable for collection due to leaching and staining.