Attic Retrofit question | Insulation/Energy/Building Envelope Q&A | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

Q&A Forums

Author	Comments
eric himmer Posted: Mar 04, 2008 08:22 PM	Attic Retrofit question Will be insulating an attic of a house with vaulted ceiling below. On each side of the house are 45 degree diagonal sloped sides that lead to the flat ceiling. Each sloped side is 6' long and has prop-a-vent with fiberglass inside. Currently fiberglass is laid across the top of the flat ceiling section. Without pulling out the fiberglass from the sloped sides, should I continue the pro-a-vent to the peak and foam over with CC 2 lb., cap the prop-a-vent and spray right to the roof sheathing, or just spray across the top of the flat ceiling sheetrock from above. Worried about moisture issues and feel insulating roof deck will be best place for the Foam. Located in NE. Any suggestions would be appreciated.
Jeffrey Pilapil Posted: Mar 30, 2008 11:06 PM	Here in VT we do alot of retrofit work on older or existing buildings and there are different approaches to handle them depending on the situation and the depth of the pockets of the client. Our general approach is to spray about 2" of 1.7 cc foam to make a good airseal (after removing that crappy FG) and then lofting about a foot of cellulose over that. Yes a proper vent path remains important in most of the options but the biggest issue over moisture is the FG in the slopes and the vent chutes i assume from experiance are crappy. We just did a slope retrofit on 15 year old house because of major black mold problems stemming from moist interior air. If the roof peak is vented, and you decide to spray the roof and end walls, i would continue the chutes and insure a complete envelope. Do you spray BioBased? I seem to remember another post about that. We do and like it.

Author

Comments

eric himmer

Posted: Mar 04, 2008 08:22 PM

Attic Retrofit question

Will be insulating an attic of a house with vaulted ceiling below. On each side of the house are 45 degree diagonal sloped sides that lead to the flat ceiling. Each sloped side is 6' long and has prop-a-vent with fiberglass inside. Currently fiberglass is laid across the top of the flat ceiling section.

Without pulling out the fiberglass from the sloped sides, should I continue the pro-a-vent to the peak and foam over with CC 2 lb., cap the prop-a-vent and spray right to the roof sheathing, or just spray across the top of the flat ceiling sheetrock from above. Worried about moisture issues and feel insulating roof deck will be best place for the Foam. Located in NE. Any suggestions would be appreciated.

Jeffrey Pilapil

Posted: Mar 30, 2008 11:06 PM

Here in VT we do alot of retrofit work on older or existing buildings and there are different approaches to handle them depending on the situation and the depth of the pockets of the client. Our general approach is to spray about 2" of 1.7 cc foam to make a good airseal (after removing that crappy FG) and then lofting about a foot of cellulose over that. Yes a proper vent path remains important in most of the options but the biggest issue over moisture is the FG in the slopes and the vent chutes i assume from experiance are crappy. We just did a slope retrofit on 15 year old house because of major black mold problems stemming from moist interior air. If the roof peak is vented, and you decide to spray the roof and end walls, i would continue the chutes and insure a complete envelope. Do you spray BioBased? I seem to remember another post about that. We do and like it.

You need to login to reply to this topic. Please click here to login.