Most property managers think about their commercial roof when there is a leak or visible damage. Poor insulation is less obvious, but it can increase a building’s heating and cooling costs.
Because insulation sits beneath the roofing membrane, it’s not easy to judge its condition from the surface. When it’s time to repair or replace it, property managers should know what is already installed and whether it still meets the building’s needs.
How Commercial Roof Insulation Works
On most low-slope commercial roofs, insulation sits between the roof deck and the waterproofing membrane. It helps keep heat inside during winter and limits how much heat enters through the roof during summer.
With effective insulation, the building’s heating and cooling systems don’t have to work as hard.
Insulation’s ability to resist heat transfer is measured by its R-value. Generally, the higher the R-value, the better the insulation slows heat transfer.
However, the insulation’s condition and installation also affect its performance. Even insulation with a high-R value may not perform adequately if there are gaps between boards, moisture damage, or other installation issues.
Why Installation Makes a Difference
Contractors can install commercial roof insulation in several ways, depending on the building and roofing system. Some contractors use mechanical fasteners to secure insulation to the roof deck, while others use adhesives. Each method has different requirements that can affect the finished roof’s performance.
For example, metal fasteners can transfer heat through the insulation, a process known as thermal bridging. This reduces the roof’s overall thermal performance and can increase heating and cooling costs. Adhesive systems can reduce this heat transfer, but contractors still need to ensure the roofing system is securely attached to withstand high winds.
Beyond the attachment method, contractors also need to consider the insulation’s thickness, the number of layers, and how the boards are arranged. These decisions affect how well the insulation works with the rest of the roofing system.
A quality commercial roofing contractor will document all these installation decisions, especially since those details are no longer visible once the roofing membrane is in place. A reliable roofing contractor should provide property managers with clear records of the materials and installation methods used, so they have that information when future repairs or replacements are needed.
What Happens When Insulation Gets Wet?
If water gets through a damaged membrane or flashing, it can reach the insulation underneath. Depending on the material and how much moisture is present, the insulation may lose some of its ability to resist heat transfer.
Water can also spread within the roofing assembly, affecting insulation beyond the area where the leak first developed.
Even after a contractor repairs the source of the leak, if the insulation wasn’t properly dried, moisture may remain trapped in the roof system, causing recurring problems. A roofing contractor should evaluate the insulation’s condition to determine whether the affected areas need replacement or whether repairing the original source of the leak alone is enough.
When Should Property Managers Evaluate Roof Insulation?
Not every older commercial roof needs new insulation. However, certain projects or changes in building performance should raise the question.
- When planning a roof replacement: A commercial roof replacement project gives property managers an opportunity to evaluate the existing insulation and determine whether existing insulation should be amended or replaced. The best time to upgrade or replace commercial insulation is when the roof is already being replaced.
- After significant water intrusion: If water has entered the roofing assembly, the contractor should check whether it has affected the insulation before recommending repairs.
- During major building renovations: Changes to how a building is used or its heating and cooling needs, may affect its insulation requirements. Reviewing the roof during renovation planning can help determine whether improvements are necessary.
- When investigating higher energy costs: If a building’s energy consumption increases, it may be worth evaluating the roof’s insulation alongside HVAC performance and other building conditions.
What Property Managers Should Consider Before Making Changes
Increasing insulation thickness can affect other parts of the roof, including flashing heights, rooftop equipment clearances, and drainage. For example, adding another layer of insulation could raise the roof surface above existing flashing details, requiring adjustments to maintain proper waterproofing.
Contractors also need to consider how the additional insulation will work with the existing roof deck and waterproofing system, along with any applicable building code requirements.
Before recommending changes, a roofing contractor should evaluate the existing insulation and surrounding roof components to determine what improvements the building can accommodate.
Looking Beyond the Roofing Membrane
When planning commercial roof work, the membrane shouldn’t be the only consideration. Evaluating the insulation underneath can help property managers identify potential issues and determine whether improvements should be included in the project.
At CRS, we help commercial property owners and managers understand their roofing systems and determine what work makes sense for their buildings.
If you are planning commercial roof work or have concerns about your existing roof insulation, contact CRS to discuss your roofing needs.
