Crawl Space Vents - open or closed? (new home, school)

[Sunflower--girl]

I bought a house on a crawl space - all previous homes have been a slabs. I keep finding conflicting info about opening or closing the vents. Any ideas here?

[bbbbmom]

I never could figure out that either but with this house, the crawl was moldy and very humid so they sealed them all up and put in a dehumidifier.

[DaysofThundr46]

I was told to leave them open. It lets the air flow through the attic space. I was told it doesnt make the house any cooler or warmer as long as its well insulated.

[TeamMorrell]

Open! The goal of the vents is to provide cross ventilation and keep the moisture levels down. The only time it is recommended that you close them is during extreme cold...which frankly is so rare and short lived here that even then it's not worth the trouble of closing them.

[Kelkmac]

Yep -- leave them open! Old school was to open and close them depending on weather and humidity, but it is now recognized that ventilation helps keep a crawlspace healthy. A couple other tips -- make sure you have a vapor barrier (the plastic sheeting on the ground) to keep moisture from getting to your framework and monitor (i know -- going down there can be yuck) for water. Standing or flowing water in crawlspace means a disaster for your home later. Early detection and correction can mean everything. eyespyinspections.net

[Nuke64]

Closed.

The common wisdom of keeping them open in summer (and closed in the winter) is wrong.

http://www.crawlspaces.org/

[TeamMorrell]

Originally Posted by Nuke64

Closed.

The common wisdom of keeping them open in summer (and closed in the winter) is wrong.

http://www.crawlspaces.org/

Nuke - read the page you sent fully. It is all about DESIGNING sealed crawlspaces. i.e. built differently than 98% of the crawl spaces out there and different than the OP's. They don't have vents. It isn't saying close the vents on your vented crawlspace.

The recommendation to keep them open stands. If you are building a new home, or can afford to convert yours to a sealed crawlspace, that it the better design, but you can't just close your vents.

[CarolinaWoman]

We keep ours open all year. Our exterminator covered the ground under our house with the vinyl sheeting. It's important to keep that area dry and the ventilation from the vents helps. Our weather doesn't get cold enough to make it necessary to close the vents.