Minnesota shed roof on a narrow lot: Attic venting problems
Our architect designed home is under construction. Its a 27′ wide (on a 40′ wide lot) x 49′ long simple shed roof. The original plan was to have soffit vents on the low side eave and the high side eave and passively vent the roof. The only thing not shown in the images linked below is that we planned to spray foam the low heal to get R55 (not possible with cellulose alone). This low heal was a result of the unfavorable code related to shed roof height:
Because of the close proximity to the neighboring house the code also requires a solid piece of drywall to covers the proposed soffit vents (for fire issues). This info came late in the game and ruins the original venting plan. The builder is understandably trying to avoid any vents through the metal roof. The other issue our builder is worried about is sucking humid combustion air into the low soffit from the other neighboring house. Picture in link: http://www.dudebrowtf.com/images/ProjectHouse/atticvent2.JPG
The architect is recommending a 1/32 HP 12″ fan mounted high on one gable and then venting the other gable’s soffit and venting across.
The builder is worried about the architect’s plan and wants to spray foam the whole roof at an additional $9k+ cost.
Looking for some recommendations. Thanks for any help!!