Return to the Old House Forum | Post a Follow-Up

Mildew smell in recently renovated porch

Posted by lalala (My Page) on
Mon, Jun 11, 12 at 22:23

We recently had the three-season porch on our 1936 house converted to a full-year porch. It is a small space (11'x7') that we now use as a playroom. Everything was taken down to studs, windows and door replaced, walls and ceiling insulated, new drywall put in, baseboard heater installed. The only thing that was not replaced was the floor, which is original. The floor is pine and has gaps of a couple of millimeters between the boards. Underneath the porch is a crawl space--just dirt. There was new rigid insulation installed beneath the floor.

Prior to renovating the porch it smelled somewhat mildewy. (We once left the porch closed up during a hot and humid spell, and it got really smelly; it never went away completely.) I had figured that the smell was mostly in the walls, but there is a lingering smell coming from the floor that I notice now that the weather is getting more humid.

Is there anything we can do about this other than keeping the windows open? Would washing the floor with a bleach solution accomplish anything?


Follow-Up Postings:

RE: Mildew smell in recently renovated porch

Your new renovation has probably tightened up the room so much that it's preventing the pre-existing small amount of air flow from the crawl space into the room from escaping into the atmosphere. I take it no effort was made to install a vapor barrier in the crawl space?

You might try ventilating the crawl space so that negative pressure pulls air down from the room into the crawl space and out and not the opposite way as it is now. Insulating previously uninsulated spaces in older houses often has unintended negative consequences - you may be trading increased energy efficiency for a disturbance in the existing intra-wall air flows. (That's usually the point of insulation and sealing it up, after all.) But those intrinsic air patterns may have been what was keeping the house dry and sound over many years.

I'm not saying you should never insulate or tighten up an older house but you have to be prepared that doing so may upset an equilibrium, with harmful, or at least problematic, consequences.


RE: Mildew smell in recently renovated porch

Only one sure solution: the crawl has to be encapsulated.

See link.

Here is a link that might be useful: Building Science Corp. on Conditioned Crawlspace

 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 Old House 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