Ensuring the right ventilation approach
I'm getting ready to build a home near Indianapolis, Indiana, and I've been referring to the Building Science material for guidance on best practices for construction. When I look through the Building Profile for a Mixed-Humid Climate: Louisville it mentions the use of rigid insulation sheathing. It also notes that in mixed-humid climates (like Indianapolis), roof and wall assemblies are best designed to dry to both the exterior and interior, but the is not always possible when rigid exterior insulating sheathings are used. It states that with insulating sheathings only inward drying is possible. For mechanical ventilation, it recommends the use of an intermittent central-fan-integrated supply.
Here's where I'm confused... If an intermittent central-fan-integrated supply is used for mechanical ventilation, won't that slightly increase the pressure of the home (relative to the exterior of the house). And won't this increase in pressure make the general flow of air to go from the interior (the low pressure zone) to the exterior (high pressure zone). If that is the general air flow through the house, won't it be harder for moister to move with the air to the interior for inward drying?
For my new home I'm planning to use rigid insulation sheathing, and I was planning to install an intermittent central-fan-integrated supply for mechanical ventilation, but I want to ensure that the system works will for proper drying of the structure and I don't create issues by using the two together in a mixed-humid climate.
Thanks for any guidance that can be offered on if these systems will work well together in my climate!
Posted Aug 17, 2014 3:43 PM ET
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