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Community and Q&A

Exhaust only crawl space

DanCK | Posted in Mechanicals on


I’m a reno contractor in Newfoundland, Canada. We often do small additions to homes and end up creating small crawl spaces.

Our strategy is to bring the new crawl space into the building envelope and use the home’s HRV to remove air from the space. This gives us a negative pressure and keeps things healthy.

We currently have a project where the home has no HRV and we’re looking at using a small exhaust fan along with a floor grille to help the air move through the space. I would love to hear from anyone who has tried this method before and if they have any feedback for how it worked out. Or if anyone can think of any issues that may arise.

Any feedback is appreciated.


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  1. Expert Member


    It's one of the code approved methods and is commonly done here in BC. I haven't heard of any problems. The only one I can think of is that if the fan pulled more air than the floor grill was happy supplying, it might try to draw air through the ground seal - although I'm not sure that would be much to worry about.

  2. DanCK | | #2

    Thanks malcolm, good to hear its in use. The BC code lays it out pretty clearly what's required so I'll use that as the guideline. We'll watch the size of the duct feeding the crawl space as well.

  3. Debra_Ann | | #3

    There could be a possible issue in humid summer climates, if the house does not have adequate AC or a dehumidifier to reduce the humidity of the air being pulled through the crawl space. Warm humid air entering a cool crawl space is likely to condense and cause mold. Might work just fine in a dry climate, though.

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