Even after the mildest of winters, such as the one we are currently experiencing here in Connecticut, it’s important to do a commercial membrane roof inspection to ascertain what damage or wear a flat or low-sloped commercial roof has sustained during the winter months.

Why conduct an inspection? A commercial structure represents a significant investment for a building owner; the roof on said building also represents a level of protection and security for both the building owner as well as the business owner or manager against production stoppages or inventory damage. Given the potential for damage during the winter months, it is extremely important to have a proper commercial roof inspection at winter’s end (as well as regularly scheduled maintenance).

A Detailed Roof Inspection

To ensure your flat or low-slope membrane roof is in good condition, you (or your roofing contractor if you don’t have the right personnel trained for this job) will need to do a complete commercial roof inspection. The inspection should include the following areas which, during our 50 years in this business, we’ve discovered tend to present problems over time:

organic growth on a flat roof

Aesthetically unappealing, algae growth can also indicate a larger drainage problem or impede proper drainage.

Surface Membranes

Whether it’s EPDM, PVC, TPO or an older product such as BUR, the integrity of the surface membrane is your first line of defense against leaks and additional damage. Your commercial roof inspector should look for blistering, bubbling, cracking, deep scratches, holes or tears in the membrane field of your roof. If you have reason to believe there is a leak but can’t find any of the above, it might be time for a “flood test” to be done, to track down any vulnerabilities.

You should also make note of any algae, fungus or moss growing on the membrane surface. If noted, schedule the removal as it can compromise the flow of water on your roof drainage system as well as deteriorate the roof surface. During the process of evaluating surface membrane, our team will also feel for substrate weakness and listen for sounds associated with related problems – both of these detection abilities come from years of experience.

Membrane Seams

You will find membrane seams where sheets of membrane roofing material meet and overlap, at the transitions between the deck and parapet wall, and wherever you see protrusions such as curbs for roof equipment (solar, HVAC), vent flashings, pitch pans, and drains. The adhesion and durability of seams are affected by temperature, moisture present during the initial installation and, in some cases, wind. Check for separated seams on deck sheets and around flashings.

Protrusion Flashing

After inspecting membrane seams, you should examine the flashing around each protrusion (or penetration) in your membrane roof. Check skylights, stacks, vents, walls, and curbs to uncover any cracks, crevices or splits which have occurred during the winter months. The most likely candidates for concern are those areas where flat surfaces transition to vertical surfaces as there is natural stress in these areas.

Roof Drains

Once assured the water-tightness of the roof membrane and that the seams and flashing aren’t compromised, the next step is to evaluate the roof’s ability to drain water. In addition to scuppers and gutters, most larger roofs have internal roof drain systems. The first and most obvious symptom that the system is not working properly is evidence of ponding of water:  either stains or actual ponds of water. 

Standing water on a flat membrane roof can cause a number of serious problems:  

  • The deterioration of caulk, tar or roofing cement
    vegetation in flat roof drain

    While “green roofs” are trending, it’s never a good idea to have vegetation in your roof drains.

  • As water expands and contracts due to temperature change, weaker roofing seams can become compromised
  • Excess water weight can test and ultimately weaken roof structural supports

While roof drains should be routinely inspected after significant storms (when rain, wind, and other elements may have knocked debris into them), the integrity of the roof drains should be examined periodically. Here you look for the following:

  • Cracks of any size in the drain domes, rings, bowls or piping. Beyond leaks, water in these cracks will expand and contract with changing temperatures, escalating potential for leaks. 
  • Drain, piping, connector or fastener rust may cause connections to loosen and lose their watertight qualities, which increases leak potential.
  • Buckled or loose flashing can cause it to pull away from the drain, increasing the potential for water incursion.

Gutters, Scuppers, and Downspouts

Equally important for a properly functioning membrane roof drainage system are the points of egress at the perimeter of the roof – scuppers, gutters, and downspouts. Scuppers, which generally sit above the roofline and further from the warmth of the building, tend to have ice form in them more quickly so they should be evaluated for damage from contraction and expansion. Each of these three components should be examined for organic debris which may have washed into them during drainage. If ponding is a problem, you may have to clear downspouts; it’s also important to check downspout terminations at ground level which may have been damaged from lawn maintenance equipment or vehicle activity.

Edge and Parapet Walls


Deteriorating parapet walls or coping stones can often be the source of roof edge water incursion.

While at the edge, it makes sense to examine this area for potential problems. First, all edge materials should be tightly secured and remain properly terminated. Metal edge fasteners should be in place and tight. If they aren’t, a professional will need to properly secure anything coming loose to close gaps that allow weather elements inside. Then, it’s time to look at the terminations on your parapet walls. These terminations should be properly sealed. An experienced inspector will look at the parapet base to determine if there are any signs of failure or cracking.

Roof Vents

Finally, a proper balance between air intake and air exhaust created by roofing vents eliminates the emergence of potential subdeck problems due to mildew or mold from incidental water incursion. Roof vents are the second line of defense here. After a thorough check of the membrane, seams and flashing around roof vent curbs (mounts), it’s also important to make sure nothing is keeping the roof ventilation system itself from functioning properly. Any potential blockages in ridge vents, power fans, turbines or roof louvers should be investigated and, if discovered, cleared by a trained professional.

Many of the aforementioned inspection points can be achieved during routine roof maintenance. However, given the investment your commercial membrane roof can represent, we recommend twice-annual (early spring and late fall) inspections by a professional commercial roof inspector. Studies show that building owners or facility managers who make semi-annual professional inspections part of their routine maintenance experience a clear saving in overall roof maintenance costs over time.

Our friends at Carlisle Syntec have created a very nice video that summarizes the basics of roof inspection which you can view here. If you’d like to learn more about the Commercial Roof Maintenance and Repair services we offer by visiting this webpage. If you’ve decided it’s time for a commercial membrane roof inspection, please contact us today to schedule a meeting.

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