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How Proper Insulation & Ventilation Create a Long-Lasting Roof

07 December 2016

Sadly, this photo isn’t a stock photo pulled off the Internet.  One of our crews came across this scenario last week after being called to a St. Paul, MN home to complete what the client thought would be a minor roof repair.  The culprit?  Inadequate roof ventilation.  The importance of working with a contractor that treats your roof as an entire system cannot be stressed enough.  Ignoring the important role insulation and ventilation play in the vitality of a roof has serious ramifications.

Three Consequences of Inadequate Insulation & Ventilation:

Corrosion: Incomplete roof ventilation and attic insulation will result in high levels of moisture.  The result is decay in the roof deck, supports, shingles, and underlayment.

Ice Dams: An ice dam is a ridge of ice that forms on roof edges and curtails melting snow from filtering off the roof.  This can lead to serious consequences, such as water backing up into the home and causing interior damage.  The correct amount of insulation and ventilation is the best way to prevent ice dams.     

Rust: A disproportionate level of moisture due to subpar ventilation can cause roof vents and flashing to rust.  This can also cause the thousands of nails used to apply a roof to begin to detach from the roof as well.

What You Need to Know Before Installing a Hot Roof:

In a traditional configuration, attics have both insulated flooring and ventilation.  Outside air has the ability to filter in through the soffits and exit through the top of the roof which creates a cold attic during the winter.  This method curtails ice dams by keeping a roof’s temperature cooler.

A hot roof differs because it has spray foam insulation directly affixed to the roof sheathing, thereby eliminating ventilation.  Temperatures in attics of homes with a hot roof are increased because without ventilation, the thermal envelope has shifted to the underside of the roof.  Though the temperature increase may only be a few degrees, industry studies have shown that those degrees make a difference.  Shingle lifespan can be lowered as much as 10%.  Shingles on hot roofs are also more likely to fade.  This has led many roofing manufacturers to extend minimal warranties to hot roofs, citing that they do not adhere to the insulation standards the shingles were designed for.  Before installing a roof, it’s also wise to verify if your municipality even allows them.  Bear in mind that even if they aren’t outlawed, certain criteria may still need to be met.