How To Install A Foundation Vent Fan

Not all Crawl Spaces will need a vent fan, but if you are needing to take excesses soil gases out of your crawl space this is the blog for you! We will discuss what it takes to install it, what other things you have to keep in mind, and how to determine how many Lomanco PCV 1 fans you will need.

Crawl Space Vent Fan Installation

We have done other blogs and videos about this, but it wasn’t directly tailored for the DIY expert; the last blog we did was Crawl Space Ventilation – Myth 4. This blog talks about the myths surrounding crawl space encapsulation, dehumidifiers, and vent fans. While the previous blog talks about myths and other misconceptions, today we’re tackling the actual installation. We want to remind you that the vent fan is the last step to ensure your crawl space is happy, and any vent fan should be paired with encapsulation and a dehumidifier.

Let’s fast forward through the crawl space encapsulation, and you have decided that you need a vent fan; but how do you determine how many vent fans you need? Get your math hat ready because we are about to take it there. The figure below is good help for an open crawl space.

We feel that this is the point where all math teachers can point at us and tell us “Told You so”, but now that you know how many vent fans you need for your crawl space. The Crawl Space Ninja method uses a closed crawl space, that means that all vents are sealed except the one that has the fan installed. This allows the fan to cover up to 5,000 Sqft.

We will give you some Pro tips on how to make it easier on you, also the video link is below if you want to watch us install one!

Crawl Space Vent fan Pro Tips.

    • Unless you are a electrician, have an electrician install an outlet close to where the vent fan will go
    • The PCV-1 has a Humidity sensor that will make it turn on ( although we recommend leaving on at the lowest humidity setting so it runs continuously)
    • The PCV-1 requires a 8″ x 16″ opening, this is usually the normal size of a concrete block.
    • Make sure you have a good drill, and good lighting.
    • Don’t use this to ventilate hazardous materials!

4 thoughts on “How To Install A Foundation Vent Fan”

  1. What about make up air. Can this be supplied by leaving a foundation vent(s) open, although they would bring in outside and possibly humid air or close all vents and draw from inside the house ?

    1. It can if necessary but most crawl spaces are not sealed enough to stop makeup air from entering around doors and floor penetrations or HVAC ducts. Also, I read air does come up from the soil. Thanks for the question. Hope that helps.

  2. Greg Collins

    If I understand correctly, you guys recommend setting the fan to run continuously on an encapsulated crawlspace? You are using the “low” humidity setting to “trick” the fan into an always on situation.

    P.S. – the information you have supplied has been critical for my DIY project – encapsulating my small crawlspace.

    1. Hello, that is correct. The EPA wants 1 CFM of air moving out of the crawl space per 50 square feet. This trickle of air according to the EPA helps remove soil gases and keeps crawl space from getting stale. Thank you for the feedback. Please post pics of your crawl on Facebook and tag us if you like.

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