Never underestimate the importance of your commercial flat roof.  It may represent 10% of your building cost, but it protects 100% of your important business assets from the elements.

A simple water leak can stop production, damage expensive equipment and can result in a complete business shutdown depending on the severity of the problem.

Your commercial flat roof is the “fifth wall” of your building and requires bi-annual inspection and preventive maintenance to maintain it in a healthy condition.

This simple guide will help you to understand how to prolong the health of your commercial flat roof.  Off to roof school!



The Basics

First things first.  You are going to need to know the general construction of your roof.  Yes, it’s flat!  And flat roofs, unlike peaked roofs, do not as easily shed water and snow.  Examining your roof regularly will ensure that issues like ponding water or plugged roof drains do not cause extensive damage resulting in expensive repair costs.

Commercial flat roofs are more “construction intensive” requiring the use of asphalt tankers, pumper kettles and specialized site safety equipment.

What to do if issues arise?

Do not attempt to make repairs yourself!  It may seem like a great cost-saving idea, but in the long run can cost more money.  Improperly effected repairs can actually lead to more damage and thus more costs to correct.  Let a professional roofing company diagnose and recommend preventive maintenance regimens for the health of your roof.

Hire a trained professional.  Here’s a quick checklist to help you identify a reliable roofing expert.

  • In business for 10 years or more.
  • Permanent business location.  Do they have an office you can visit?
  • Licensed and bonded.
  • Verifiable references.  Make sure you actually follow up on references.  Don’t just ask for them and not make that important call!
  • Proof of financial stability.  This should take the form of a letter from their bank indicating the company is in “good standing” financially.
  • Holds commercial roofing insurance, specifically covering completed options to include torch applied and hot asphalt applications.  Limits of five million dollars are the norm in today’s market.
  • Have verified Workers Safety & Insurance Board (WSIB) coverage.  This is extremely important!  If your roofing company isn’t covered and an accident occurs, you could be held liable.
  • An official health and safety policy.  A good roofing company will have a specific list of safety procedures their employees have been properly trained to follow.

Once you’ve found a trustworthy roofing contractor, hold a meeting and nail down all your expectations as to budget and timeline.  This will help to ensure everyone is “on the same page” and can help to reduce surprises along the journey.  Never begin a roofing job without a detailed plan.

The Construction Process

Finally, you’re going to need to learn about the steps in the construction of a flat roof to ensure your roof is properly designed and built.

Step 1 – Preparation

This is when old roofing materials are stripped from your roof and disposed of (properly and according to environmental regulations).  The deck surface is prepared, which could involve removing rotting wood, replacing metal panels or resurfacing concrete, depending on the deck surface you are dealing with.

Step 2 – Vapour Retarder

This step involves laying down a material designed to prevent moisture from leaking into your building.  The materials used will depend on the type of roof deck you are dealing with.  Regardless, the result should be to retard moisture.

Step 3 – Insulation

Insulation is then placed over the vapour retardant layer and secured in place using mechanical fasteners or hot asphalt.

Step 4 – Membrane System

There are a number of options when it comes to roof membrane systems.  These range from embedded hot asphalt to modified bitumen.  No matter what system is used, the purpose is to prevent leaks and move water off the roof.

Step 5 – Drains

Drains are added to ensure water doesn’t collect on your roof.  Interior roof drains are connected to drainage pipies.  Open edges use gutters that include downpipes.

Step 6 – Sheet Metal

Sheet metal is then added to reinforce vulnerable roof areas.  Any sheet metal used should be 26 gauge, pre-painted galvanized steel or copper.

Step 7 – Caulking and Sealing

Key areas of your roof, like points where metal or masonry meet will require added sealant to prevent leaks.

Step 8 – Complete, Legal Clean-up

Finally, your roof contractor should have included (in your contract) an agreement to ship any and all roof debris and leftover materials to a legal disposal site.  Check your contract carefully for this guarantee.  If a contractor is caught illegally dumping waste, you could be charged as well!

Well, there you have it.  A complete guide to understanding commercial flat roofs.  Remember, your roof is an important investment.  Make your investment count by ensuring it’s built (or repaired) correctly.

Need A Quote?

Give us a call if you would like to get a quote or price your roof repair/replacement options. We will send out one of our roofing technicians to assess your roof in person and provide you with an estimate.

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Book our Healthy Roof Inspection, and you’ll know exactly what’s happening up on your roof.  We’ll inspect your roof and provide a written report.


Don’t wait ‘til it leaks!  Book an inspection or call us at 866-248-9488 or email your request to