Does new insulation in attic require adding roof vents?

Q. A carpenter recently laid batt insulation R-38 in the attic of our three-story wood frame structure. The attic has done well without vents of any sort since the house was built 80 years ago. Does the new insulation require that we put roof vents in the attic for summer high heat and humidity? Lee Johnson Winchester, Mass.

A. It's likely the old attic could use some vents, either roof or gable, gravity or powered. Cross ventilation above the new insulation would be somewhat helpful in making the insulation itself more effective. You may want to consider a thermostatically controlled fan which automatically exhausts attic air heated above a certain temperature.

Whether the vents should be installed in roof or wall depends on the actual structural conditions up yonder. For an on-the-spot decision ask your local building inspector as to advice on vents: where, how many, and what kind.