Having a new roof installed

Originally posted in the Record-Courier

By C. DWIGHT BARNETT

Q: We are having a new roof installed and they said they would put on a vent at the top of the roof. The vent would be the full length of the roof and they said it was part of the price we are paying for the roof replacement. I was doing research and found your article about a ridge vent and it may not always be a good idea. Is this something I should bring to the attention of the roofing company?

A: Yes, homeowners should always be informed about a company or a product before signing a contract for work to be done on their home. A ridge vent is an excellent form of attic ventilation when installed properly. Most homes have an overhang for the roof called a soffit. When a ridge vent is installed, there must also be an equal area of venting at the soffits. If you do not have the correct amount of soffit vents, this could be an extra unplanned cost to correct.

The square feet of free venting at the soffits must be equal in area to that of the ridge vent. Free venting is the area of the vent that is not covered with screening or other obstructions to air flow. A piece of twelve-inch by twelve-inch vented soffit material, one square foot, only has around nine square inches of free venting. Likewise, a foot long piece of ridge vent has about nine square inches of free venting. If the soffit and ridge vents are not balanced, the attic could be hot in the summer and have higher humidity in the winter.

During high winds and rain, an unbalanced ridge vent has been known to draw moisture into the attic space. The soffit-to-ridge venting must be balanced and this means there should not be other roof vents, gable vents, cupolas or turbine vents open to the attic space.

C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.

Date : 4/28/2017