DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > General Home Improvement Discussion > crawl space

Help Support House Repair Talk by donating using the link above.
Thread Tools Search this Thread
Old 08-11-2009, 01:25 PM  
Junior Member
Join Date: Aug 2009
Posts: 1
Default crawl space

Hoping someone can help me out. I purchased an older home, built approx 1920's and a 20'x20' addition was added to it approximately 30 years ago. This addition has a crawl space that i can acces thru the main house foundation. The crawl space is approx 3' high with a dirt floor. I am looking to eliminate moisture and insulate the heating pipes underneath....vapor barrier??....any suggestions?

There is already some kind of barrier, though i can see mold in some spots


homehelp is offline  
Reply With Quote
Old 08-11-2009, 02:09 PM  
Senior Member
Join Date: Aug 2007
Posts: 693
Liked 2 Times on 2 Posts


You need to cover all the dirt floor with heavy plastic (sold in rolls at the big box stores). Seal it to the walls with roof mastic.

If the vents can be closed off in the winter, just insulate the walls instead of trying to insulate the whole floor. Use 6" thick fiberglass with the vapor barrier away from the wall. If it is vented and you can't seal it in the winter, insulate the floor with 6" fiberglass using wire inserts between the studs to support the insulation. Vapor barrier goes up, facing the floor..

If it smells musty in the summer you may need to vent it during the warmer months.

travelover is offline  
Reply With Quote
Old 02-16-2011, 03:26 PM  
Senior Member
Join Date: Dec 2009
Posts: 253

Travelover has some good points. In addition, you can use a dehumidifier to prevent moisture in your crawl space area. Tested it a lot of times and it really helps. I guess you should try it out as well.
“You can always get someone to love you, even if you have to do it yourself
frozenstar is offline  
Reply With Quote
Old 02-18-2011, 08:48 AM  
Senior Member
Join Date: Jan 2011
Location: Hartfield VA, VA
Posts: 2,004
Liked 271 Times on 214 Posts
Likes Given: 77


Did vents get installed when they built it? By code there needed to be vents at least every 10'.
The best ones are automatic opening, Then there's no need to have to open of close them. There about $20.00 each and sold at any box store.
The trouble with adding a dehumidifire is who's going to go under there to empty it? It would need to have a hose added and let it dump into a sump to be pumped out, or a condinsate pump added. Everyone I see is put under the house and no ones ever gone under the house to check on it. By the time they do the control circuts is so corroded it's not working.
For a dry crawl space the grade under the addition must be higher then the outside grade, if not fill needs to be added. A simple layer of 6 mil. black plastic over the soil held in place with 16" insulation ties bent in half will hold it in place. There must be ventalation. most codes want the vents to be 12" above outside grade.
There has to be working gutters or the waters just going to work it's way under the house. Thee can not be mulch piled up againt the house or it will hold in moisture, Grade must run away from the house.
Your going to have to trust me on this one, at least 80% of the work we do is on 100 plus year old houses and we have been under 100's of homes and have seen what works and what did not work.
I've seen companys come in and cover all the vents with foam, tape all the seams in the vaper barrier, run it up the walls and nail it in place with strapping, add a dehumidifier. But they never condisioned the air, never raised the grade, never at least fill in the low spots, never added gutters. There was so much water left laying on top of the plastic due to bad grading and mulch againt the home that all the floor joist were covered with black fungus and looked like they had been painted with black spray paint.
What a lot of insurance companys used to do with old ballon constructed homes is make them completly seal up the foundations because of the fire hazard with that type constrution. I had been under the homes before and then years later after it was closed up. Every one of them now had fungus growing because of the lack of ventalation.
joecaption is online now  
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter DIY Home Repair Forum Replies Last Post
Crawl Space Dehumidifier jhk49 Insulation and Radiant Barriers 4 10-31-2014 01:02 PM
Carpet over concrete in crawl space...venting in crawl space? Hoss Insulation and Radiant Barriers 7 12-23-2011 08:01 AM
Crawl Space Moisture UPMIch General Home Improvement Discussion 2 08-18-2009 07:58 PM
Help! Water in the crawl space! tom.walker General Home Improvement Discussion 4 05-08-2009 08:25 PM

Newest Threads