Crawl Space questions


Old 07-07-14, 09:16 PM
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Crawl Space questions

I live in Indiana. I have a 40 year old 960 Sq foot ranch home on a vented crawl space with original (and torn) vapor barrier and apparently a little bit of pea gravel too. It has some type of gravity drain. I have suspected crawl space humidity issues for several years. But.... can't seem to convince my husband of dad about it. My husband is starting to come on board though.

3 or so years ago we had dripping wet fiberglass insulation held up by chicken wire stapled to joists. We had a low spot in the house. A contractor jacked up the low spot. Made a new pier and took out all of the fiberglass insulation. He replaced the fiberglass with really thick foam board type insulation along the premier of the concrete block wall.

We leave crawl vents open in summer and closed in winter. We have electric baseboard heat and window air conditioning units.

My husband went under the house to do something last week and it felt humid in there. Enough to concern him. He also said the parts of the dirt floor where the vapor barrier is torn is like mud, despite no standing water. So now he is joining me in my concern, finally.

I have purchased a wireless temperature and humidity reading device yesterday. We may need to move it a bit deeper into the crawl, because as of tonight it is reading the same as the outside air. I know this because I purchased a second unit for outside monitoring. But if it's correct where it is.....It was 77 degrees and 90% humidity inside the crawl and outside. Exactly the same.

So now what? If we decide to seal..We can't condition the crawl space air with baseboard heaters and window air units.

How sealed is sealed?? We can NOT afford an expensive clean space system. And we don't need a crawl space so clean you can store stuff in it. We just need lower humudity.

What about the foam already on our concrete block walls? We can't easily or inexpensively remove that to run vapor barrier up the crawl wall. Can we just put the vapor barrier under at the bottom or over the insulation?

What do you suggest??
Old 07-08-14, 02:11 AM
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The humidity in a properly vented crawl space will never be lower than the outside air humidity. If you want it drier then you will have to seal it off from the outside and install a dehumidifier.
Old 07-08-14, 04:30 AM
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Welcome to the forums Amanda!

Not my area of expertise but I'd think laying down plastic would be your first step. Ideally it would be sealed wall to wall but I would think an imperfect plastic barrier would be better than none. Can you increase the ventilation or air flow under the house?
Old 07-09-14, 05:48 AM
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6mil plastic will degrade as you're already found out,,, IF you have to buy from the apron/vest store, 19mm pond liner is the best they sell,,, try stego vapor barrier & not very $$$ - great stuff [ no $ interest ],,, tape/seal seams - install up the walls - use termination strips,,, if you close/seal the vents & run a dehumidier, you'll have a ' conditioned crawl space ',,, you won't have to heat OR cool it - its still ' conditioned '

IF there's foam on the bsmt walls, hope its open cell so the wall's moisture can breathe - less chance of mold that way.

bood luck !
Old 07-09-14, 06:30 AM
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Hi Amanda and welcome to the forum.

There are a few steps that need to be taken in the right direction. Much of the air you breathe inside your home comes from that crawlspace, yuck.

The foam that was applied to the crawl walls, was it spray foam or rigid foam panels? Did he also foam/seal the wood rim directly above the masonry walls? How thick (approximately) is that foam?

Here is an article on crawlspaces. Even if you don't do it all, if you move in the right direction it will get finished at some point.
BSI-009: New Light In Crawlspaces — Building Science Information

Old 07-09-14, 06:36 AM
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Crawl spaces open to the outside have insulation in the ceiling while crawlspaces which are conditioned and sealed from the outside have insulation on the walls. In other words, switching from one to the other is no small task. I would go with stadry's suggestion and work on the vapor barrier.

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