Flat roofs are most commonly found on commercial buildings. They are generally less expensive to install (fewer materials), can be installed quicker, they provide more usable space for HVAC units and other equipment and how they look doesn’t matter. No one is looking at “curb appeal” for most commercial buildings.
They aren’t just for commercial applications, though.
They are common on residences in locales like southern Arizona where less rainfall combined with high temps is ideally suited for low pitched roofs, limiting the space heat can get trapped between it and ceilings.
Even in our wet climate they have become more common. With a slight pitch to help shed water, they have the same great advantages as when used in commercial applications. The large surface area can increase heating and cooling efficiency under the right circumstances. The additional usable space is ideal for solar panel installations and rooftop gardens or terraces to add more outdoor living space.
Properly maintained, they don’t negative impact that curb appeal. For some, the clean look of a freshly coated roof flat or low pitched roof is better than the look of shingles.
Maintenance is key
Flat roofs eliminate some concerns like torn shingles, though they can be more susceptible to other problems. Unlike traditional peaked roofs, they tend to be more “out of sight” and therefore, more “out of mind” for the homeowner. This can lead to serious issues in a shorter period of time than with other roof styles.
Low pitched roofs limit water to run off.
The low pitch means any debris on the roof could create a dam effect. Without a higher pitch, there is less force behind the water to easily flow over debris or push it off the roof. This can create ‘ponding’ or small pools of water, collecting on the roof. Without enough sun, those small ponds do not evaporate quickly. With more debris collecting on the roof and consistent days of rain, those ponds can grow. The increased water weight can lead to a weakening of the structure below and the roof started to sag. With more rain, the problem is compounded.
Low pitched roofs are coated to seal them.
These coatings are generally flexible, though flexibility breaks down as it ages. Temperature fluctuations force expansion and contraction of the roof surface and the coating. Direct sun in the summer months combined with the heating effect from below will cause the coating to stretch, shrinking back in the colder winter months.
This break down in the coating’s surface allows it to pull away from flashing and to be more easily damaged by tree debris. It can simply crack on its own as well. Once the coating is compromised, water can gain access to the decking and roof structure easily. With water moving slow over its surface or ponding, it has a great chance of making its way into those cracks.
Proper care and maintenance of a flat roof
While they are flat and easy to walk on to inspect yourself, we caution against it. The risk of a fall may be less likely than on a more traditional DIY roof inspection or maintenance, but most homeowners will be less familiar with flat roofs. This increases the chance they miss something.
When we inspect flat roofs, we are looking for:
- Slits or cracks in the coating
- Build up of dirt and debris
- How the roof deck feels when walking on it
- Areas of ponding or evidence there has been ponding
- Working drains (depending on roof style) among other items.
We recommend flat roofs be inspected at least annually and having all repairs performed at that time, with the exception of repairs for ponding. (This needs to be done in the drier summer months).
Every five years your roof should be re-coated by a professional with a quality elastomeric coating like Henry’s 100% Acrylic Enviro-White Extreme Elastomeric Roof Coating.
Additional basic maintenance tips and preventive measures include:
- Trim trees next to the roof line to limit debris.
- Keep gutters free and downspouts unblocked.
- Limit walking on the roof to only when necessary or to areas designed for it.
- Deal with leaks promptly.
Flat roofs may require more attention and maintenance, but properly cared for they will last for years.
Schedule time to have it done now if yours hasn’t been inspected within the past year.