It’s time to stop ignoring the actual facts… open crawl space vents in the hot Summer (and cold Winter) are not a good idea for a lot of reasons.

It is now being recognized that the smart thing to do is to close your crawl space vents… your foundation vents, at least parts of the year if not year-round based on your specific situation (humidity in the air where you live, temperature where you live, etc.).

Open crawl space vents year-round can be bad news for your home.  Consider this:  When your vents are open there is air flowing in your crawl space and that air contains moisture – it’s called humidity.  You can’t just open your vents and let the air in without the moisture (the humidity).  That continuous flow of moisture into your crawl space is not a good idea.  You don’t leave your front door open when it is 90 degrees outside or when it is 30 degrees outside so why leave your vents open… it is the same thing.

For 40 years (since about 1982) building codes around the country have encouraged homeowners to vent their crawl space. The belief was that venting would help dry out your crawl space.  Some people are still stuck with this notion even though 40 years later the evidence is in, and that air doesn’t dry out your crawl space… it allows humidity in.  Mold needs that humidity to grow.  With your foundation vents open there is a price to pay.  Even though 40 years ago they thought it was a good idea… it’s not.  At one point in time they said cigarette smoking was good for you too.  Close your vents… at least in the hot, hot Summer and the cold, cold Winter.  Perhaps if you want to allow some fresh air (along with the moisture/humidity) into your crawl space then do it in the milder months of Spring or Fall.


When it is 80-90 degrees outside and your crawl space vents are open it is like your home is sitting on top of a heating pad.  Your air conditioning bills go higher and higher.  Summer heat coupled with open foundation vents and your home turns into a furnace.  And even worse, Summer heat coupled with Summer humidity and you have the perfect environment for mold growth.


More than 50% of the air you breath inside your home comes from your crawl space. If there is mold in your crawl space then you are ingesting it thru your breathing.  Not a good idea.  Where it is dark, hot and moist there is the potential for mold growth.  Of course, mold growth is bad for your breathing but it also can cause wood rot and attract unwanted pests.  Leaving your crawl space vents open can reduce the quality of indoor air.


When your vents are open it costs you more to cool your home in the hot Summer.  With Vanity Vents in place the air in your crawl space will be up to 20 degrees cooler.  With Vanity Vents in place when it is 90 degrees outside it is only about 70 degrees in your crawl space.  No longer are you sitting on a heating pad… now the 70 degree temperature in your crawl space is much cooler than the Department of Energy’s recommended sweet spot for air conditioners to balance energy savings and comfort in your home.  I don’t know about you but I typically set my air conditioner system to about 73-74 degrees but wherever you set your thermostat… it will cost a lot less money to cool your home if you have your vents closed and the air temperature in your crawl space is closer to 70 degrees rather than 90 degrees.  You don’t want your air conditioner running for long hours just to keep up with the 90 degree temperature outside.


Don’t leave crawl space vents open for another day. Cover your foundation vents with Vanity Vents.  Vanity Vents take 3 seconds to install so it is very fast and easy to put them on and take them off if you decide to only use them parts of the year. See for more information.  Lock out moisture, mold, hot air and those pesky critters.

You will spend less energy on heating or cooling AND your indoor air quality and comfort will be so much nicer.  Not to mention the instant curb appeal that Vanity Vents bring to your home (they come in 5 fabulous colors).

For more information: Visit, email or call us we’ll be happy to help… 503-548-7444