Flat Roofs – What Condo Owners Should Know

Flat Roofs – What Condo Owners Should Know

For many people, condo living is the way to go. Unlike with a detached home, the flat roof is a shared expense that a condo owner must consider when buying in. If the building or group of buildings is quite big, roofing repairs can be expensive.

This article highlights some of the main conditions and parts we look at so you can be better informed about how we do our job, when inspecting a flat roof. There are several other considerations and conditions that inspectors look for, but this is a general guideline detailing some of the most common flat roofing conditions.

Larger buildings, such as condos have some sort of flat roofing system. Although there are several types of flat roofs, such as tar and gravel, torch on or inverted roofs, they all must keep the water out. They do this by having a tightly sealed surface rather than a shedding system that a steep roof would have.

As inspectors, we are concerned with a number of details such as position of drainage, flashing, especially around the plumbing stacks, chimneys, skylights, vents, edges and the wall-roof connection points. Flashing, or materials used at roofing joints, connection and angled areas are designed as reinforcement to stop leakage.

The surface of a flat roof can make it more challenging to keep water out in comparison with a sloped roof. Some of the most common concerns that we look for are:

Blistering/Bubbling/Splitting – Blisters can be a result of air or water trapped between the layers of the roof. As the roof heats up from the sun, the trapped gasses expand and create bubbles and blisters. They can become very large. Over time they can break through the surface and cause the roof to split. If this goes unchecked then water can enter and weaken the roof, later leading to possible leaks.

Patches – It is common to see patches of flat roofs. Patches indicate past leaks or weak areas. If the patching has not been done correctly, these areas are likely to leak again. In my opinion, patches are just a band-aid solution to a larger problem festering. As a general rule, if 25% of the roof is covered with patches, then the roof needs to be replaced.

Water Ponding or Pooling/Vegetation – Most people have noticed pooling or ponding without really paying attention to it. You may have seen it when you are looking at roofs from higher buildings. Flat roofs are not actually supposed to be flat. If built correctly, they will slope to the drainage area provided. Pooling or ponding happens when it rains and the water stays behind because it has not drained properly. When water is sitting on a roof surface for longer than 48 hours, it is considered ponding. Excess water on a roof can be very heavy. The added weight can change the roof structure, create depressions and make a poor slope worse. If this happens, ponding will continue and the drains will not work as intended. Ponding will lead to vegetation. Vegetation that is not purposely landscaped on a roof will grow roots, hold moisture to the surface and deteriorate the surface, reducing its lifespan.

Old/Damaged – With older roofs, especially built up roofs, the best way to determine how worn out they are, besides the obvious signs, is to walk on them and see how they feel under our feet. We look for loose areas, depressions, deteriorated surfaces, cracking, discolouration, etc.

A good way to find out if a roof membrane is old is to look at the metal flashing to see signs of corrosion and rust. The actual age of the roof is less important than the remaining life of the roof. Like any system, proper maintenance will prolong the life of a roof.

No Protective Surface – All flat roofs need a protective surface to protect it from the sun and help keep the roof cool. The major problem without a protective surface (gravel for example) is a much-shortened life expectancy for the roof.  We look to see if there are bald spots, displaced gravel, exposed felts and soft spots, to name a few.

The challenge inspectors face is not being able to inspect the roof. At times management companies deny us access to the roof due to liability reasons. So if your inspector is not allowed on a roof, ensure that you know what the strata council is up to for their roof maintenance plan… it can affect your budget.

For more detailed information or questions about flat roofs just ask me or contact a professional roofing company in your area. If this information has been valuable to you, please share it with others 🙂

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