Traditionally in the Midwest, homes are insulated with fiberglass or cellulose insulation. However, a newer trend being seen in homes is the use of spray foam insulation. Just as the name implies,
this type of insulation comes in spray cans. It’s a combination of resin and chemicals such as polyurethane & isocyanides. As the insulation is sprayed, it expands and fills up the entire area it is being applied to. The term “hot roof” comes in because the spray foam insulation is being affixed directly to the roof sheathing which removes the need for ventilation.
How Do Hot Roofs Differ From Traditional Roofs
Attics typically have an insulated floor and have ventilation. Air from outside is permitted to come in through the soffits and exit through the top of the roof which creates a cold attic during the winter months. This method is intended to deter ice dams by keeping the roof cooler. When your attic is filled with spray foam insulation to create a hot roof, your attic’s temperature rises because the thermal envelope is shifted to the underside of your roof because ventilation is not present.
Hot Roofs & Roofing Warranties
Industry studies show that shingle temperature is only raised by a few degrees with a hot roof. However, these few degrees can lower shingle lifespan by up to 10% and cause shingles to fade. GAF, North America’s largest manufacturer of residential and commercial roofing, offers a “Golden Pledge” warranty which covers roofing material and labor for 50 years. This warranty is not pro-rated. However, those with a hot roof are not eligible for GAF’s highest level of warranty because a hot roof does not have the insulation standards that their asphalt shingles were designed for. Before moving forward with a hot roof, check with your roofing manufacturer to make sure that doing so will not void your roofing warranty. Be sure to check with your city to see if they have restrictions on hot roofing before proceeding with your project.
Perks of a Hot Roof
The unit of measurement for insulation is called the “R-Value”. The R-value measures how well insulation is able to resist heat going through it. The bigger the R-value, the better it will insulate your home. A hot roof contains the highest R-Value because there are no chances for air to leak. If the attic contains ductwork, it won’t need to be insulated because there is no energy loss. A hot roof prevents energy loss and can lower your utility bills.
Am I Allowed to Have a Hot Roof? 
In the state of MN, the following cities PROHIBIT Hot Roofs:
- Apple Valley
- Delano
- Eagan
- Eden Prairie
- Hopkins
- Lakeville
- Maple Grove
- Plymouth
- Shakopee
- Saint Louis Park
- Woodbury
In the state of MN, the following cities MAY Allow Hot Roofs if Certain Criteria is Met:
- Bloomington
- Brooklyn Park
- Chanhassen
- Coon Rapids
- Elk River
- Minneapolis
- Richfield
- Roseville
- Saint Paul
Tune into AM 830 WCCO on Saturdays from 9:00-10:00am hosted by Denny Long and Andy Lindus to ask questions regarding your home improvement projects. Call us now at 1-800-873-1451 or check us out on the web at www.lindusconstruction.com to schedule a free in-home estimate for your home improvement needs today!
