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Sealing and conditioning attic in 100+ yr old Dutch Revival

CharlesTBetz | Posted in General Questions on

Seeking advice on properly changing our roofing system.

We live in Minneapolis (energy zone 6A) in a small 1905 house (footprint 50’ x 50’) with complicated gambrel roof. Asphalt shingles installed ~1990 (Purchased 2002). With growing hobbies, we need more “working space” in our small house, so decided to open up the closed attic space and turn it into storage space. Some roofing folks may advise against that but we pulled the trigger: We have already opened a second floor bedroom ceiling, and installed one of those drop-down staircases. The attic floor was ~5” deep with vermiculite, which has been removed. It should be noted that this insulation was ineffective since we had plenty of melting, ice dams, and 6’ icicles on steep sloped roof. Hard to imagine that was all from sunshine.

So: What is the most effective configuration for a roofing system, given these considerations?

What about insulation? We are strongly liking the idea of insulating the underside of the roof deck with some form of spray foam. This conditions the attic space so we can go in and out no matter the season. Also should reduce ice damming etc.. Is it also recommended to insulate the attic floor?

What about ventilation? We have existing ridge vents (see pics). If we condition the attic space, is ventilation necessary or counterproductive? From what we’ve read so far, if we condition the attic we should remove the roof vents—true? Have yet to identify any intake vents. In houses of this age (1905), are there always intake vents?

We work with contractors to be sure the job is done right, but we’re trying to educate ourselves so we know what to ask for.

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi Charles.

    The most cost-effective approach to insulating an attic is often to insulate the attic floor. For this to be effective, the floor needs first to be air sealed. Here is a good article on that process: How to Insulate an Attic Floor. However, you are unlikely to be able to get enough insulation between the joists to be efficient and still have a plywood floor for storage without doing some framing work.

    So, you may choose to insulate the roof instead. An insulated roof can be vented or unvented. To get acquainted with what is involved with insulating the roofline, check out How to Build an Insulated Cathedral Ceiling.

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