Anatomy of a Commercial Roof

Anatomy of a Commercial Roof

The anatomy of a commercial roof system includes more than just the visible top waterproofing layer that most people think of. A properly installed commercial flat (or low-slope) roof has several other critical components as well.

The anatomy of a commercial roof includes:

The Structural Roof Deck

The roof deck is the weight-bearing layer of your roof system that supports the roofing materials built above it. In most commercial structures, the structural roof deck is a thick-gauge steel fastened to support beams. Sometimes the deck material may be plywood or concrete.

Vapor Barrier

Depending on your property type, there may be a thin vapor barrier laid on top of the roof deck before the next component is installed. Vapor barrier is needed when the interior needs to be air conditioned and also will have interior moisture present, such as commercial kitchens.

Roof Insulation

A critical component of any flat roof is the insulation layer. The most common type used today is polyiso rigid foam board insulation. The purpose of any insulation, including commercial roof polyiso, is to keep heated or cooled air inside the building without allowing external air temperature to get through. This helps keep heating and cooling energy costs down. Insulation effectiveness is measured by “R value”, and in Denver commercial flat roofing the most common value required is R-30. In order to achieve R-30 insulation, a minimum of 5-inch thick polyiso foam board insulation is needed.

Roof Cover Board

Cover boards used to be less common, but the National Roofing Contractor Association (NRCA) began recommending cover board for all commercial flat roofs in 2006. Non-combustible gypsum and glass mat boards help reduce fire risk and impact from large hail, as well as provide a smooth flat surface to install roof membrane.

Roof Membrane

The final layer on a commercial roof is the weatherproof roofing material. This is the exposed roof surface that has the most important job of sealing the internal structure from external elements. The most popular options in 2021 are TPO and EPDM single-ply membranes, but there are other options such as built-up roofing (BUR) and modified bitumen as well.

Anatomy of a Commercial Roof

Other Commercial Roof Components

In addition to the roof layers, a commercial flat roof will also include the following:

  • Edge flashing
  • Penetration flashing (skylights, HVAC, vents, etc)
  • Fasteners or adhesives
  • Drainage (commercial-grade gutters, scuppers, drains, and downspouts)
  • Roof covering (if applicable – such as rock ballast, concrete pavers, or coatings)

We suggest having a professional commercial roof inspection at least once a year, and ideally twice due to the harsh weather we face in Colorado. During your inspection, the roofer will inspect all the components listed here and identify any problem areas. They can then present you with an action plan for any suggested remedies to make sure your roof’s life extends as long as possible.

Is it time for your commercial property to have it’s roof inspected? Contact our team today to get your inspection scheduled.