For the most part, there appears to be a commonly accepted delineation that commercial properties will have flat roofs while residential properties are generally constructed with sloped or pitched roofs. Although there can/will always be an exception to any so-called rule-of-thumb, even the most casual observer would probably agree that houses usually have sloped roofs while flat roofing is the norm for:
- Shopping malls
- Manufacturing plants
- Super-size department stores
- Condos and apartment buildings
However, the choice of roofing style extends well beyond the simplest distinction of the type of property. There are indeed several fundamental reasons, and a few less obvious ones, why flat roofs are preferable in commercial settings and pitched/sloped roofs are installed in the residential sector.
From the commercial property perspective, flat roofing offers a number of advantages and benefits to the owners and/or managers of the types of structures listed above. The factors supporting the preference for flat roofs in this sector include:
- Installation is somewhat easier and can be accomplished over less time
- A lower cost of installation (tied in many respects to time and/or labour)
- Provides for maximum use of interior space from the floor to the ceiling
- Ease of maintenance – from the perspective of working on a flat surface
- Allows greater utilization of roofing space (heating, ventilation, a/c units)
- Ease of access – for maintenance needs or perhaps for storage purposes
- Green roofing options (possibly mandated within some municipal by-laws)
- Steel frame (vs wood) improves capabilities to meet fire codes/regulations
Considering the residential property point of view, there are similarly valid reasons why sloped roofs are generally preferred over the flat variety:
- Smaller surface areas – easier to attain angles needed for proper drainage
- Offer a greater aesthetic presence or a better curb appeal than flat roofs
- May need less overall maintenance (if regular/annual inspections are done)
- Can offer a longer lifespan – particularly based on the roofing material used
- Less tendency for snow/ice to collect – reduces stress due to excess weight
In addition to the protection of persons and property, a critical function for any type of roofing relates to the drainage of rainwater and melted snow/ice. Without an effective drainage process, any flat or sloped roofs can succumb to leaks, in turn leading to more serious/severe damage to both the interior and exterior of the structure – and the water drainage process is another differentiating factor in installing flat versus sloped roofing.
Due to the overall larger size/square footage of many commercial structures, it would be enormously difficult, not to mention economically unfeasible, to install sloped roofs. For the purposes of achieving effective water drainage, the peak of a sloped roof has to be a specified height above the top edge/eave of the structure itself. Said in another way, a defined downward angle is required to correctly drain water from a sloped roof – and this angle must get steeper as the area of the roof, and volume to be drained, gets larger.
As an example, and without delving too deeply into the mathematical calculations, for a commercial building roof with a surface area of 100,000 square feet (perhaps 1,000 feet by 1,000 feet), the peak of that roof would likely need to be greater than 40 feet above the outer edge of the roof. From a purely structural perspective plus the installation and material costs for such a slope, flat roofing would be the better choice for this building.
One additional point about flat roofs – this reference is actually a misnomer/misleading.
Flat roofing is not actually 100% flat; it is more accurate to describe these types of roofs as a series of very low-pitched or low-sloped pieces (imagine squashed pyramids) that help drain away water through the very shallow valleys or troughs formed between the adjoining sides.
Pre-Winter Inspections Are Critical Aspects To Proper Flat Roofing Maintenance
Despite the many advantages of flat roofs for commercial structures, good maintenance practices must be implemented on a regular basis to ensure the proper protection of all tenants and clients, as well as the contents/property within those buildings.
Part of these maintenance practices includes a thorough inspection, on at least an annual basis, by certified flat roofing professionals like Avenue Road Roofing. Our team has extensive experience and expertise with flat roofs relative to:
- Inspections and assessments
- Recommending best solutions
- Installations and repairs
- Year-round maintenance
Looking for flat roofing services that meet your needs and performance expectations over the coming winter? Call our experts from Avenue Road Roofing today at 416-785-5129 or contact us to book your pre-winter inspection as soon as possible.