Air changes needed in a conditioned attic and crawl space
I previously asked about insulation in an conditioned attic/”unvented” roof assembly – will be built in Climate zone 5A.
I figure that we should have some sort of air changes in the attic (or is that crazy)? Should we have ERV exhaust and supply vents in the attic and plan for a certain number of ACH?
On a similar note, any recommendations for ACH in the crawl space, which will also be sealed within the building envelope. I read somewhere (that claimed reference to IRC) to plan on 1 cfm per 50 sq ft of crawl. If the crawl spaces are open to the mechanical room in the unfinished basement, which communicates with the living space, that I can place an exhaust port for the ERV at the far end of the crawl.
If you are wondering why I am asking, or what we’re doing in a nutshell, there will be insulation sandwiching the roof sheathing. We are using radiant hydronic heating and cooling – no forced air, but will have an ERV and integrated dehumidifier. Given that, the attic will be conditioned by the fact that it is included within the air sealed/insulated building envelope, but not because we will have HVAC ducts supplying otherwise conditioned air to the space. The foundation and exterior walls will be ICF.
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