Why Commercial Roof Insulation Is So Important

Sky-high energy bills. 

Constant HVAC maintenance costs. 

A 6 or even 7-figure flat roof that was supposed to last 20 years…lasting a mere 12.

What do these problems all have in common? They can all be caused by a poor commercial roofing insulation job. 

Insulation is one of the most important parts of a proper commercial roof. Still, unfortunately, many building owners and property managers know little about it - and many contractors do a poor job of selecting and installing it.

At GIDEON, we've installed millions of square feet of virtually every roof system available and helped numerous building owners save hundreds of thousands of dollars with the right insulation installed the right way.

Yes, a lousy insulation job can cause all 3 of the problems mentioned above. But the right insulation, installed professionally, can solve them. In fact, the right insulation can create net savings for your business of hundreds of thousands of dollars per year. In this article, we'll discuss the importance of commercial roof insulation: how it can lose you money if done wrong and save you money when done right.

Why Insulation Is Such an Important Decision

Significant impact on operating costs

One of the biggest reasons insulation is such a vital decision is its tremendous impact on your recurring energy bills. In the United States, energy costs account for more than 30% of office building operating expenses. 

When evaluating how a particular type of insulation will impact your energy usage, there are 3 essential factors to consider: the K-value, the R-value, and the U-value. 

K-value: This measures the thermal conductivity of a material, i.e., how well it conducts heat. The lower the K-value, the better the insulation.

R-value: This measures how well a material resists conducting heat, i.e., it is the inverse of the K-value. The R-value is calculated by dividing the thickness of the material by its K-value. A high R-value indicates good insulation; ideally, a material should have a high R-value even at low thicknesses.

U-value: This measures the heat transfer rate through all the layers of a building element (like an entire roof assembly, a wall, or a floor). It includes all layers of the component and accounts for any gaps or fixtures. The lower the U-value, the better the insulation of the element. 

When discussing insulation with your contractor, the two values to focus on are R-value and U-value. 

R-value is based simply on the chemical composition and construction of the insulating material, and different kinds of insulation will have spec sheets showing their R-values. 

U-value, because it considers the insulating capabilities of the entire roof assembly, depends on how the insulation is installed. Gaps between insulation boards will cause thermal bridging (when airflow moves between the gaps), while the screws that hold the insulation in place will cause thermal shorting (when the metal conducts thermal energy). The tighter the seams between insulation boards and the fewer screws used, the better the U-value…and the more you'll save on your utility bills. 

Moreover, a high U-value will reduce your utility bills by reducing your electricity consumption and the price per kilowatt hour, as your utility company determines your pricing based on your historic usage. 

The highest U-value can be obtained using spray foam insulation, as it eliminates the gaps and fasteners that cause thermal bridging and shorting. 

The other way insulation impacts your energy costs is by reducing HVAC maintenance. A well-insulated building puts less strain on your HVAC system because it reduces the work the system must do to maintain the set temperature. Less stress translates to fewer repairs and a longer lifespan for your HVAC system.

Significant impact on upfront costs

Unfortunately, insulation is an area where some contractors try to cut corners to lower their bids and win contracts.

Why do they do this? Because insulation is one of the key contributors to a roofing bid's price. If you can reduce the amount or the type of insulation, contractors can outcompete other roofers on price and potentially win a bid. This is one reason it's so important not to evaluate roofing bids based on price alone.

Roofers typically skimp on insulation in 3 ways:

#1 Not building a tapered insulation system

While flat roofs may have some degree of slope built into the decking itself, a tapered insulation system is often required to create a proper slope that allows adequate water drainage. This is particularly the case on older buildings, which often have no slope built into the decking.

Tapered insulation systems consist of panels of insulation of different thicknesses, which, when laid out in a specific pattern, create the proper degree of slope on a roof and channel water toward drainage points.

The panels in a tapered insulation system are designed to be thicker at one end than the other, creating a wedge shape. When these panels are arranged correctly on the roof, they form a slope with a specific pitch, often expressed in inches of rise per foot of run (such as 1/4 ":12", meaning a rise of 1/4 inch for every 12 inches of horizontal distance).

Without a properly designed taper system, water will sit on the roof for prolonged periods, creating downward pressure on the membrane and magnifying the sun's UV rays, prematurely deteriorating the membrane. 

The lack of a proper taper system is often responsible for the drastically reduced lifespan of many single-ply roofs.

#2 Using cheaper, lower-quality insulation

Some contractors may use lower-quality insulation to cut costs. While this might save you money initially, it can lead to higher energy bills in the long run due to the insulation's poor performance. Plus, inferior insulation materials can degrade more quickly, resulting in the need for premature replacement.

How can insulation degrade over time? In 3 ways: 

#1 Moisture permeation: If the membrane is compromised and vapor seeps into the insulation, it will lose its insulating capacity. 

#2 Off-gassing: Rigid foam board will off-gas over time and lose R-Value. If it began at R-6.0, it may degrade to R-4.9. 

#3: Compression: Insulation may compress over time, losing thickness, which will also reduce the R-value.

#3 Simply not installing insulation

Shockingly, there are instances where insulation is left out altogether, with only a cover board installed. This will raise your energy bills substantially and may even cause condensation issues within the building during the winter, as warm, moist interior air comes in contact with a much cooler roof.

When discussing your options with your contractor, it's important not to simply go with the lowest cost available but to figure out how to get the best insulation option for your budget.

Strongly impacted by regulations

In the United States, commercial flat roofs are required to use a certain amount of insulation with a certain minimum R-value. These regulations vary by locality, with some places setting mandates at the state level and others setting them at lower-level jurisdictions. 

What happens if your insulation doesn't meet the requirements? You may face fines or other penalties from your local municipality, you may be denied when filing an insurance claim, or your roof system manufacturer may void your warranty. 

It is very important to discuss local building codes with your contractor and local municipality to ensure you meet regulatory requirements.

Conclusion

As a business owner, efficiency is the name of the game. Well,  few things contribute more to a building's health and efficiency like proper insulation. Now that you've learned why insulation is a critical factor to consider when planning a roof repair or replacement check out our article on the two most common types of flat roof insulation: rigid foam board and SPF. Chances are, your contractor will recommend one of these, so arm yourself with the right information, so you can make the right choice for your building.