REMOVING HEAT, COLD AND HUMIDITY FROM ATTIC SPACE
QUESTION FROM JOE FROM SPOTSYLVANIA, VA:
I have a hip roof attic space over a 2 story home. The ceiling joists/attic floor joists are 2x8 and filled will unfaced fiberglass. This performs adequately in its role. However, HVAC contractor installed air exchanger in attic. There are two complete systems, one in basement treating basement and first floor, second in attic serves second floor. As you can imagine, attic gets hot in summer, cold in winter, affecting cooling and heating ability. Additionally, the insulated round flex duct is running through unconditioned space. Access is decent. I built a 1600 SF addition to the home completely except for concrete so I have significant building skill.
I wish to reduce attic temp, essentially create a space where the unit can work more efficiently though I know getting to a point of "conditioned attic" is really not feasible. Two routes I've considered. Unfaced fiberglass between rafters or foil faced foam applied to face of rafters (foil inward?). Ideas, tips, suggestions?
Thanks so very much.
ANSWER FROM THE INSULATION DOCTOR:
Thanks for your question.
I have three recommendations for you. The first would be to check that a proper vent has been installed at the end of each truss run.
My second would be to install an exhaust fan in the roof that has two controls on it. One being a humistat and the other a thermostat, both being controlled by the temperature and humidity in the attic. If you cannot find a manufacturer with a dual control you can have your electrician wire it so that it is controlled by both. Using this method will cool the attic in the summer and eliminate moisture in the winter.
My third recommendation would be to install a second layer of unfaced insulation to provide yourself with a total R-value of R-49. I do not recommend insulating the roof rafters. Insulating the roof rafters may cause serious damage to the plywood, the roof rafters and significantly shorten the lifespan of your shingles.
I hope this information is useful to you.
The Insulation Doctor