What are some typical causes of flat roof leaks?

Flat roofs offer great protection for many commercial buildings in the city. Keeping them in tip-top condition is vitally important, especially this year, as BC will experience a La Niña weather pattern, bringing above-average precipitation.

When a flat roof starts to leak, it can lead to all sorts of problems. Mould and mildew (which are health concerns), structural damage, and even costly roof replacement are likely scenarios for leaking roofs. So it pays to keep an eye on them. Here are some of the typical causes of flat roof leaks.

Standing or Ponding water

Flat roofs--aka low-sloped roofs--don’t shed water as quickly as sloped roofs. So they tend to be more prone to damage if anything causes water to remain on the roof. There is generally a 48-hr grace period before water starts to seep through the roof’s membrane. 

Causes of ponding water tend to be clogged gutters and drains; membranes damaged by age, weathering or roof traffic; roof structures like vents, pipes, hvac units, etc.; and debris on the roof like leaves and branches. Regular flat roof maintenance will help with all of these issues by identifying problem areas and fixing them.

Age

Like most things, roofing systems deteriorate with age. Membranes can start to blister or crack and allow water to enter the building. Blisters are caused by trapped moisture heating and expanding which then separates the roofing plies. Cracks form after long-term exposure in the sun, as roofing materials gradually dry and become more brittle. Both of these issues need to be fixed as soon as possible by a professional commercial flat roof repair team.

Installation Issues

Though called flat roofs, they’re not totally flat. The almost invisible slope on flat roofs allows water to slowly drain off. It’s crucial that this slope is calculated correctly at the beginning. Any errors in installation make issues like ponding more likely. Seams need to be correctly sealed and flashing around roof edges, as well as around vents, pipes, gas lines etc., all require proper installation according to manufacturer’s specifications.

For the best results when it comes to the health of your commercial roof, take a proactive approach. Perform regular inspections and if problems are found, have them repaired as soon as possible. These easy steps go a long way toward keeping your building dry and secure well into the future.

Laurentian Roofing offers high quality, cost minded installations and repairs for commercial roofs. To all our customers in Vancouver and across the Lower Mainland, including Burnaby, from Chilliwack to Whistler, we wish you a warm and happy holiday season.