2020 Boise Idaho Real Estate Blog
Crawl space design Main The Durable Green Home
We are seeing more conditioned crawl spaces instead of vented crawl spaces how come? why are they different? what do I need to know? A vented crawl is less likely to have mold problems? My crawl space has a fan in it? if I have a vented crawl what do I need to know? where do I get help?

This is the main topic of a lot of building science and seminars around the country. What you need to understand is that this  is different for each climate. In our high dessert dry climate, we have many vented crawl spaces. Theses crawl spaces were constructed of vented crawls with perimeter insulation-Where were the adults when this decision was made? Lets see, I am going to vent the crawl and insulate the perimeter?  lucky for those homeowners the home are losing so much energy to the crawl space that the pipes don't freeze, among other problems.

This is not a good strategy. If we build a vented crawls space then the floor should be insulated, the pipes should be insulated, the ducts should be insulated, vapor barrier should be installed correctly, and the home should have the vents calculated to provide ventilation at least per code, not be obstructed, and the home should be air sealed from the crawl space. Oh Yes, I know this will shock someone, but the vents should remain open year round not closed. www.buildingscience.com Is this the case with our crawls? NO! I can tell you from experience that most homes, especially new ones don't have enough vents to meet code, vents are obstructed, air leakage is extreme from crawl to the home, ducts and pipes are not insulated, floor insulation is not installed or installed incorrectly, etc. You need to have it inspected by a Home Performance Specialists www.natresnet.org Another good source for proper construction techniques is the journal of light construction.

So enough on vented crawl spaces, what about conditioned? Do they have mold? Mold or moisture problems will happen with conditioned or vented crawls spaces alike. if the crawl space is high in moisture, or wet, you need to correct the problem and get it dried out! vents or small fans will not do this! Conditioned crawls are like a mini basement, they are conditioned by pulling a small amount of air from he home, into the crawl space to condition  it and then venting that air out side. This will keep the crawl space at relative the same humidity and temperature as the home, ducts, pipes, etc are all within conditioned space now. The home is more comfortable, and we are not bringing cold air into the building in the winter through foundation vents, or hot humid air in the summer through foundation vents ( can you say condensation?). For  those of us who doubt condensation occurs-take a cold beer out of the fridge in July and see what happens on the out side when you take it out to the BBQ. Conditioning the crawl space  is accomplished by using a small fan rated at continuous use (7 days a week, 24 hours a day) and pulling air out of the home through the crawl and out the home. This must be done correctly as well. See www.eeba.org for upcoming ACI conference in Portland Oregon. This will be one of the main topics of discussion.

What do I do if my home is in a flood plain? This is a topic for later discussion. Ness Drainage recently put on a seminar on this subject in Eagle, there should have been more people present! The flood plane grows wider every time we encroach upon it or build in it. Think we have affected the boundaries in the last 10 years? Oh Yes,   

Posted by Tad Duby at 2/11/2007 3:24:00 PM
Comments (1)
wet crawl space
This is not a good strategy. If we build a vented crawls space then the floor should wet crawl space
be insulated, the pipes should be insulated, the ducts should be insulated This is a topic for later discussion. Ness Drainage recently put on a seminar on this subject in Eagle, there should have been more people present!
Posted by on 5/16/2017 12:39 AM
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Michelle Penick, Build Idaho Client Real Estate Services

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