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Crawl Space Under House

Help! I have this crawl space under the house it is large enough to kneel in it. I live in a high water table area and sometimes it seems to not dry out. I am only able to get air under the house from 3 sides the back has a low porch and no air can get in or out.

My problem was about 8 years ago I notice that inside the house you were able to put a finger under the trim and with that the beams under the house were rotting due to the insulation holding the moisture ( lots of it). :( I pulled out all of the insulation and have since had the beams... $6,000 of them replaced.

My floors are cold in the winter and I have not put insulation back in the crawl space... I am afraid that it will hold the water/moisture and rot the wood again. Is there insulation that I can put there?
I am a single mom... not afraid of doing the work but could use some help with this problem.

Re: Crawl Space Under House

Does the water come up high enough to soak the insulation and floor joists or is it just dampness. If it is just moisture from being damp I would insulate and cover the insulation with plastic, sort of a vapor barior, it will keep the insulation dry and avoid mold and mildew. If the water comes up and soaks everything you should have some sort of drain put in. Hard to say not being able to see whats going on. Good Luck!!! :)

Re: Crawl Space Under House

Kathy ...... is water from outside getting into the crawl space?
If so then you need to take care of proper drainage by ensuring the landscape slopes away from the foundation and down spouts drain as far away as possible.
If the water is extreme you might need to have some sort of drainage system that include a sump pit and pump to discharge any water entering the crawl space.

If the crawl space has a dirt floor and the moisture is from that then completely cover the floor with a minimum of 6 mil poly. This will prevent the moisture from migrating up from the dirt floor.


If it is just moisture from being damp I would insulate and cover the insulation with plastic, sort of a vapor barior, it will keep the insulation dry and avoid mold and mildew.

This is something you Don't want to do.
By covering the insulation with plastic on the underside of the insulation will trap moisture causing mold,mildew and rot.

You would better to cover the insulation with a house wrap material. This product will allow the moisture to breath out, minimizing any trapped moisture.

It's difficult to tell what your conditions are over the internet.
In some cases the vents can be contributing to the issue. Having passive vents open all the time can allow humid air inside the cooler crawl space and condense. If the winter temperatures are cold enough this humidity can freeze within until warmer temperatures thaw turning things into wet conditions.

One method .... depending as to the requirements in your area ..... is closing off the vents at least in the winter ..... and insulating the perimeter walls of the crawl space with rigid foam insulation. Doing this will raise the temperature within the crawlspace helping to keep the floor above warmer and minimizing condensation issues. If you live in an area with very cold winters also insulate the underside of the floor to assist with keeping things warmer.

If you have the budget then having 2 lb closed cell spray foam applied to the underside of the floor would be an excellent product and is immune to moisture issues.

If vents for the crawl space are needed or required you might consider having fans installed ina a push pul configuration controlled by a humidstat. Basically one fan would draw outside air in and the other fan would blow air from the crawlspace out. These would only turn on based on a set humidity level selected on the humidstat controller.

Hope this makes sense and helps:)

Re: Crawl Space Under House

If I read your thread right your crawl can only get air from three sides, is your crawl open or does it have walls?? If it is walled in and only dampness and not standing water you might want to follow this link, http://www.crawlspacedehumidifiers.com, it might be worth your while.
I apologize for telling you to attach the plastic to the floor joists, I also told another person in this forum the same thing and was corrected by Timothy Miller, at which point I thanked him. Unfortunately I was given bad info a few years ago and did mine the same way but has since been fixed. Good Luck!!! :)

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