Coming Together at the Seams: Flat-Roof Repairs

The old saying goes, "when it rains it pours." You might never truly understand the wisdom of this maxim until your flat-roofed home or business starts coming apart at the seams.  

Here are some tips to help you find issues with and repair your flat roof from breaking up at its seams.

Finding your Leak

Locating your Seams: because the vast majority of leaks on flat-roofed structures emanate at the roof's seams, the first step to repairing leaks will likely be finding your roof's seams. These seams are interlaced across the surface of your flat roof but also extend to edges that connect your flat roof to the body of wall structures, chimneys, and other fixed surfaces connected to the permanent structure.

  • The easiest way to locate flat-roof seams is to look for slight rises that extend across the roof. Once you've located one seam, a pattern should soon be obvious. Most flat-roof seams are between 14 to 18 inches in width.

Sourcing the Leak: one of the biggest mistakes novice roofers make when repairing flat-roof leaks is correlating ceiling repairs with roof leaks. Just because water might be leaking in your bedroom doesn't necessarily mean that your leak is located above your bedroom. In fact, the damaging liquid is likely seeping through a compromised seam, running beneath the roof surface, collecting at a lower point, and leaking through your ceiling at the point. When searching for leaks, scout for the following signs.

  • Gaps between the roof edge and solid structural elements (chimneys, wall edges, and so forth)

  • Fissures extending across roof seams

  • Divots or undulations located on or near roof seams

Because water runs downhill, it's relatively easy to source the leak responsible for ceiling damage in your home by tracing a path from the damage on your roof to the ceiling damage in your structure. If the ceiling damage is directly "downhill" from the roof damage, you know that you've found your culprit. Even if the damage doesn't appear to be connected to a roof seam, it is advisable to repair the seams closest to the damage.  

Repairing your Leak

Now that you've located your leak, you can repair it. Because flat roof repairs require using pliable patch and repair materials, you will need to take some precautions before attempting your repair job.

  • Wait for a dry day when temperatures do not plummet below 55 degrees (F).

  • Sunny and breezy days will also speed up the drying and setting process needed to seal your roof damage.

Once the forecast looks favorable, you should begin by prepping the roof for repairs. You can use a sharp trowel or utility knife to cut out damaged sections of roof. Next you will need to vacuum out the damaged section of the roof so that it's free of debris like dust, dirt, leaves, or sand.

After the damaged section roof is prepped, you can apply a rubberized or epoxy roof-sealing product. While you are applying the roof sealant, it's critical to remember the following:

  • Tamp down the roof sealant with a broad side of a wide trowel or roofing hoe.

  • When tamping down, you must make sure the sealant achieves maximum density and uniformity.

  • Add extra sealant to the edges of the repaired section.

  • Smooth this excess so that it is extended uniformly and parallel to the roof's seams.

  • After allowing the sealant to dry (for the duration recommended by the manufacturer), add an additional layer of sealant, making sure that the damaged section and the adjacent seams are level.

Coming apart at the seams is no way for a person or a flat roof to exist. Luckily, these tips can help you find and repair your damaged flat roof.