The Top 5 Causes of Flat Roof Leaks

It’s obvious that flat roofing does not have a significant amount of incline. Because of this, water does not have a steep slope to run down and may be more prone to leaks if the roof is not maintained properly. Here are the five most common causes of leaks on a flat roof. Most of these problems can be resolved through commercial roof repair, though the age and overall condition of a roof might make replacement the most cost-effective option.

1. Damaged Roofing Materials

Any type of flat roof can sustain damage that results in leaks. Built-up, modified bitumen or single-ply roofing may develop leaks after a major impact. Pooling water and wear over time can also result in blistering or cracking. It may be more difficult to find the source of a leak in a built-up roof covered with a top layer of gravel. Although there is good news. Once the damage has been located, pretty much any material can be patched.

Punctures or tears in single-membrane EPDM, TPO or PVC roofing materials may also result in leaks, which can generally be repaired with sealant or patches. It is important to fix damaged roofing materials as soon as possible to prolong the lifespan of a roof. Consult with roofing experts to determine the best approach to commercial roof repair.

2. Loose Collars or Flashing

Any structural components routed through a roofing membrane run a higher risk of leaks. Rain collars are used to deflect water away from open penetrations such as drains, HVAC units or vent pipes. Other components such as field wraps, pipe boots or pitch pans also prevent water from penetrating a roof and structure. Check the condition of these components during regular roof inspections. Protip: The area surrounding penetrations is usually one of the first places to look for leaks.

A roof may also feature several types of flashing. These protective metal components direct water away from penetrations and can prevent damage as an asphalt roof expands and contracts due to changes in temperature. Flashing around the edges of a roof can also prevent high winds from lifting and loosening roofing materials. Make sure that flashing is in good condition during inspections and check the fit between flashing and the roof when searching for a leak.

3. Installation Issues 

Roofing materials must be properly installed to prevent leaks. For issues like these, you’ll likely need to hire a skilled professional to inspect the roof to determine if a repair or replacement is needed. Any type of roofing requires training, but some materials pose particular installation and commercial roof repair knowledge that only an experienced professional would know.

For instance, modified bitumen involves a labor-intensive process of applying multiple layers. A torch-down method poses fire hazards, while cold-rolled technology requires the use of roofing tar. The size of rubber EPDM roofing materials can make installation more difficult, and any air pockets present in rolled-out roofing may result in leaks down the line. TPO and PVC are newer roofing materials that also call for specialized expertise during installation. Even spray-on coatings must be applied evenly to avoid leaks, which takes a lot of training to get right.

4. Poor Drainage and Pooling

Standing water is the most common underlying factor for leaks. While pooling may not immediately result in a leak unless roofing materials are damaged, loose or incorrectly installed, water that remains on a roof for longer than 48 hours will eventually wear down materials and can penetrate through seams, flashing or any other breaches. Signs of pooling may be evident immediately after precipitation or in the form of concentric rings of dirt left behind by evaporated water.

The best ways to prevent pooling is to ensure that a flat roof is properly installed, perform regular maintenance and arrange for commercial roof repair. Flat roofing should not be completely level. A slope of at least a quarter-inch per foot is necessary to direct water toward drainage. Roof drains, scuppers, gutters or downspouts must be kept clear for drainage to function properly. In addition to wearing down materials and raising the risk of leaks, standing water also adds a significant amount of weight to a roof that can cause structural damage.

5. Degraded Materials

Every roof wears down over time, even with professional maintenance and repairs. The average lifespan of a built-up roof is about 15 to 20 years, while modified bitumen may last 10 to 20 years. The durability of single-ply materials depends on the composition and design. EPDM, TPO or spray-on roofing can last up to 20 years. A PVC roof may have a lifespan as long as 30 years.

Any roofing material can last longer with regular inspections and timely repairs. Pooling water and an overall lack of maintenance can cause materials to degrade more quickly and result in more leaks throughout the lifespan of a roof. The type of material used may determine the likelihood that leaks will be caused by membrane damage or loose collars, flashing or seams. Any of these problems are better fixed as soon as possible, before water can do damage to the underlying building. Rely on roofing professionals for commercial roof repair and replacement.

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