Crawl Space Encapsulation with Ventilation | Where Does The Makeup Air Come From

[@r2_rho]

This is a question I've been fighting with for days now trying to wrap my head around how to install the vent fan. Thanks for all of your knowledge, you've been incredibly helpful on my encapsulation project.

[@inspectorcluseau6084]

Great information in this one.

[@49thparallel1]

Hi, does crawl space encapsulation include sealing off any active hvac registers and returns in the crawl space in addition to sealing foundation vents? Thanks.

[@CrawlSpaceNinja]

We seal foundation vents with dehumidifier installed. If hvac vents in crawl space to supply air, may want to seal that too.

[@demobp7405]

I live in charles town west virginia and I incapsulated my crawlspace with the 12 mil vapor barrier from your store. I also installed the pink foam board between the foundation wall and vapor barrier that you buy from home depot. I seal all the vents. I do have the Tjernlund model V2D vent fan which is 220cfm. My crawlspace is the entire size of my house, the living space is 1,344 width and length and the height is roughly 4.5ft tall. Is this fan over kill or will it do. I also have a pipe that goes to a T under the vapor barrier that vents out through the roof which was installed by the builder when home was built. I also have a dehumidifier in Crawlspace. Please let me know whats the best option, right now I sealed all vents and removed the 2 fans I had in 2 of the vents because they were pulling water through the master shower drain into crawlspace. Thank you

[@CrawlSpaceNinja]

Sounds like you have a good setup. The 1 cfm per 50 sq feet is a guideline and most fans can blow more air than based on smaller crawl spaces that but that should still be ok.

[@brandongraser2939]

I know this is expensive but what I like to do is to is get a heat recovery ventilator and use that as the makeup air . And have one vent if it's approved by a professional HVAC contractor. My idea for the HVAC vent is NOT to dehumidify. it's too cool and heat the space .I find this very important especially if you have plumbing down there you don't want plumbing freezing. Although that's not very likely with encapsulated crawl spaces. still it's very refreshing to go in a nice pretty white crawl space that's well lit with lights and smells clean and dry and the air is crisp. By the way the HVAC vent for the crawl space is only put in if the ductwork is down in the crawl space. And it's not leaky.