High-sloped residential properties are quite common in Edmonton AB. In fact, many reputable and experienced roofing companies in Edmonton AB offer plenty of services geared towards residential property owners. However, low-slope residential property owners have their respective set of problems, which involve finding and dealing with flat roof leaks in heavy rain.

A high-slope roof has an easier time than a flat roof during heavy rainstorms. Even with poor gutter systems, the latter can still throw water on the ground reducing leak risks. Flat roofs will likely pool water in the same situation. Furthermore, pooled water and internal roofs make it difficult for homeowners to find their roof leaks. Fortunately, SF Gate has an excellent guide geared towards finding leaks in residential flat roof homes.

Flat Roof Leaks in Heavy Rain: Areas to Check

  1. Clear any debris from the roof. Look for places where tree branches may have gouged or torn the roofing material.
  2. Walk around the roof looking at the metal flashing. Typically, there are two layers of flashing. The inner layer, or step flashing, covers where the wooden sheathing of the roof meets the chimney, skylights or other holes in the roof. A separate outer layer of flashing, the counter layer, serves as an independent protective layer to the step flashing. These two layers of flashing need to be able to expand and contract with the roof. If that doesn’t happen, the flashing may allow water to leak under the roof’s coating.
  3. Examine the collars around plumbing vents. The collar should have a flange that protects the opening in the roof, and its material should not show signs of cracking or decay.
  4. Look for evidence of patches on the roof with roofing tar or caulking. These are temporary patches, and they often fail over time. (Continued)

A huge pooled rainwater mass is the primary reason for flat roof leaks in heavy rain. Water has a massive density in huge volumes. It will continue to push against the flat roof material until it bends and breaks under pressure over time.

However, even if your low-slope roof is properly sealed with all flashings in good shape, roof structures such as skylights and chimneys can play a huge role in increasing flat roof leaks in heavy rain. Flat Roofs by Pegram has a great explanation on the risks of skylights and chimney leaks.

Flat Roof Leaks in Heavy Rain: Roof Structure Risks

Leaking Skylight

It is not uncommon for skylights to leak during heavy rains. This does not necessarily mean the skylight is damaged, but that the condensation from the rain and runoff has a higher chance of leaking through.
Caulking has left gaps that rainwater is seeping into.

In most cases, placing a bucket under the leak will do as a temporary fix. After the rain stops, find a roofing inspector immediately to assess the damages from the leak.

Chimney Leaks

Chimneys are designed to do an adequate job of keeping the elements out, but your chimney could be the cause of your leaking roof. Homes with chimneys are commonly facing problems with roof leaks.
The outer structure of your chimney often retains water, which can make the roof leak in a hard rain.

You must also make sure the shingles and flashing surrounding the chimney are in proper working order.
The flashing is a piece of sheet metal that covers the overlapping areas of the chimney and roof. Two layers of flashing is applied to the chimney and roof, and a sealed with a high-quality urethane caulk.
Naturally this caulk becomes loose over time and creates a pocket for rainwater to seep in. Often times reapplying the caulking could work as chimney leak repair, but flashing may need additional maintenance and a trained eye. (Continued)

If flat roof leaks in heavy rain happen because of pooled rainwater, it does make sense to improve your low-slope gutter system. On high-slope properties, gutters act as a shield that prevents rainwater from saturating and destroying yards and gardens. Flat-roofed homes can do away with pooled water thanks to an efficient system.

Flat Roof Doctor has a great list of areas to inspect that will help gutter systems become clean and efficient to use. If you’d like to get your gutter systems in check, this is the list you need on hand.

Flat Roof Leaks in Heavy Rain: Inspecting Gutters Thoroughly

Flat Roof Debris and Gutter Drainage

Flat roofs collect an abundance of debris that can’t be removed daily. During rainstorms, this debris gets washed into the gutter trough and clogs it, preventing proper drainage. Over time debris accumulates in the trough, causing it to overflow, which compromises the exterior walls and the foundation with water infiltration.

It is essential to keep the roof free of debris at all times. Doing so, will allow water to flow freely to the tough, through the downspouts and leader pipes, and away from the building for proper drainage.


If there are branches that hang over your flat roof, we recommend that you remove the debris from the roof and the gutters as often as you rake leaves or mow your lawns or yards. The easiest way to remove debris from flat roofs and gutters is to use a handheld leaf blower.

Flat Roof Edging and Gutters

Flat roofs should be pitched or sloped towards gutters for positive water flow. Even when they are, we often see that the edge of the roof is slightly higher due to a tar build-up, from repeated repairs, preventing water from flowing into the gutter. This can cause ponding on the roof, which can lead to leaks. Gutters should also be flush with fascia board to prevent water from flowing behind gutter troughs, if not, water will damage the walls or paint.

If you’d like to improve your low-slope roof gutter system or repair existing flat roof leaks in heavy rain, you can count on DDCL to help you. We have decades of experience serving Edmonton AB properties with knowledgeable, courteous, and dependable roofers. Contact us today to get started on your path to better residential roofing.