How To Locate a Flat-Roof Leak

How To Locate a Flat-Roof Leak

The difficulty of locating a flat-roof leak depends on roofing materials. A built-up roof covered with gravel may make finding a leak more of a challenge. Singly-ply roofing membranes simplify the leak location process. Find out more about the measures professionals take to pinpoint the location of roof damage causing a leak. The condition of the roof and severity of damage determine whether the next step is a repair or commercial roof replacement.

Clear the Roof

It is easier to identify signs of damage on a roof that is free of debris such as fallen leaves or branches. Single-ply roof membranes or modified bitumen with a smooth top are easier to inspect for signs of damage than built-up roofing covered with gravel. Roof repair specialists will walk around the roof and look for signs of damage or wear.

A membrane may have visible signs of blisters, cracks, punctures or splitting. 

The most obvious signs of leaks on a gravel-covered roof are exposed tar in areas where gravel is missing. Tar that is leaking tends to show signs of bubbling or cracking. Depending on the extent of damage, further testing may be necessary to identify the source of a leak, and if bad enough,  commercial roof replacement may be necessary to stop leaks on a heavily damaged or worn roof.

Check Flashing, Collars and Seams

It is also necessary to check the condition of protective features such as collars or flashing near penetrations or around the edges of a roof. A roofing repair professional will check the tightness of seals around these common leak locations. It may be necessary to sweep gravel away from drains or flashing on a built-up roof to inspect the condition of the tar underneath.

Some single-ply roofing materials have seams that may be prone to loosening and admitting water. For example, materials such as multilayer modified bitumen and single-ply EPDM and TPO are rolled out in large sheets during commercial roof installation to reduce the number of seams. One of the advantages of PVC roofing is that the hot-welded seams on this material actually become stronger than the untreated material. Additionally, any gaps, spacing or weak points on a roof made of any material are likely to result in leaks.

Examine the Condition of Patching

If a roof has been patched after sustaining damage in the past, this area may be more prone to leak in the future. Depending on the material, patches may simply adhere or require hot air welding. Roof repairs done by skilled professionals tend to be less likely to leak again than DIY patches. However, even the best patch may leak again if the same area of the roof is exposed to impact or if the roof has run the course of its lifespan. A roof that already has many patches may require commercial roof replacement to put a stop to leaking.

Look for Low Spots

A flat roof should not be completely flat. A slope of about a quarter of an inch per foot is necessary to promote proper drainage. As a result, certain areas of a roof are lower than others. If water tends to collect in these areas and remain standing for longer than 48 hours, this pooling may degrade the condition of roofing materials.

Any dips or divets in a roof are likely locations for leaks. Over time, the surface of the roofing materials in these areas wears down and water can seep into the roof and penetrate the structure. Even if water is not currently standing in these locations, look for concentric rings of dirt that indicate that water was present until it evaporated or leaked. 

Other signs of a leak may include small holes or splits in roofing materials. The severity of damage determines whether repairs or commercial roof replacement is necessary.

Try the Hose Test

One way to test for a roof leak is to spray suspected sections of the roof with a hose and wait 10 minutes while checking for indications of water dripping inside the structure. The best way to perform this test is to work backward from central drains or gutters and keep track of which areas have been sprayed.

Testing the condition of a roof with a hose can take hours and may not be helpful for indicating the precise locations of leaks, as water may be entering in more than one spot and feeding through the structure to one or more leak locations in the interior. A roofing specialist may rely on moisture scanning equipment to quickly obtain more precise results.

A commercial property owner may be able to perform a preliminary inspection of a flat roof after a severe storm. Although, it is a good idea to contact a roofing professional if any signs of roof damage are present. Leaks should be fixed as soon as possible to minimize damage to the roof and the structure below. Persistent leaks may necessitate costly water damage restoration and commercial roof replacement.