Return to the Basements Forum | Post a Follow-Up

Crawlspace ventilation in an old house

Posted by tanama (My Page) on
Sat, May 26, 07 at 1:57

I've been trying to research this, and the more I read, the more I'm confused by conflicting information.

My 80+ year old house is about 80% over a 2.5'+ high crawlspace with block walls, with a small interior basement. On the SW side I have a removable solid entry door (pt lumber with insulated back). On the SE side I have an approximately 1.5x2' window that's rusted just a little bit open and won't budge. On all sides I have 1-2 (each side) apprx 12" x 4" oval openings in the block that have metal grates in the back, but that are curretly closed up with pieces of 1" thick foamboard that I cut to fit to reduce drafts under the house in the winter. I just had a central heat/air system put in, so I have insulated ductwork running through the crawlspace. I have plastic on the ground and insulation under the floors in the crawlspace. There is no insulation on the walls of the crawlspace.

I just don't know what's the right thing to do for the summer. Do I open up and ventilate the crawlspace as much as I can or keep it closed?? I'm presuming that since it's not a conditioned space, that I should give it as much ventilation as possible in the summer, including possibly replacing the door with a grate and finding a way to open that window, to keep down mold and mildew. But I keep reading other things that say I should keep it locked up tight which doesn't really make sense to me for an unconditioned space but I'm not going to pretend that I know what I'm doing.

So, can anyone explain whether I should try to keep it closed up, or if I should open up just the oval vent holes, or if I should try to keep it as open and ventilated as I can?


Follow-Up Postings:

RE: Crawlspace ventilation in an old house

Building Science Corp.'s Dr. Joe lists vented crawlspaces as one of the top ten dumb things to do in the South--and the North.

However, before attempting any changes he advises: "Be sure to consult local experts and code officials before attempting unvented attics or crawl spaces on your own."

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Basements Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here