Hi, my hardwood floors are cupping. They looked like the photo on the left.

http://www.hardwoodinstaller.com/hardwo ... allers.htm

I have lived in this home for 15 years and the house is about 20 years old. I don't recall when the floors start cupping. It has been a few years. Recently, an interior decorator was alarmed when she saw the floors and mentioned there may be too much moisture in the crawl space. So, I had a crawl space vendor go underneath and he said the soil is wet and took lots of pics, including insulation drooping from the weight of being moist. He also tested the moisture on the floors. Some areas measured 18, some 16. He suggest that I encapsulate the whole crawl space. Question: will that solve my problem? Or there is more to it, such as moisture in the house, or no moisture barrier between the subflooring and my hardwood floors.

A hardwood floor guy came to inspect the layers on one of the vents. Forgot what he saw or if he said there is a moisture barrier, but I recalled him telling me that when the floors stop cupping, he can sand it down and refinish the floors. Does that mean the floors will not cup again?

Can you help me find out what the problem is and what is the best solution for my floors?

Thanks,
Chloe[/img]

Get the crawl space moisture under control, by covering the soil with plastic moisture barrier. Get dehumidifiers(more then one going in the crawl space) let the timbers under your home dry down to 10% moisture content and turn the dehumidifiers off, and see what the temp, humidity and joists moisture content equilize at.

Then have the floor sanded.

Thanks. Would you suggest using one of the crawl space professionals, or is it something that a handyman can easily do?

It needs to be done properly but it is not difficult. A handyman could do this.

That's really good news! It will save me a few bucks. The crawlspace vendor gave me an estimate of $8500 to encapsulate my crawl space. Any idea where I can purchase the plastic liner? The guy gave me 2 samples, a 12 mil and a 20 mil cleanspace liner. Looks like they are the same material as the pool liner.

8 mil BLACK polyethylene is all that is needed. Overlap the seams by 12" Do a neat and tidy job. Lap up the foundation walls by 6" or so. Cover ALL the earth. Weight the film down with bricks, rocks, gravel, sand but NO wood products. Make sure all foundation vents are open and clear and not blocked by shrubbery and the like. Once covered, the moisture content should drop rather quickly. On average, in about one week. Check with a moisture meter. BTW, you can get the plastic film at most hardware stores. 20 mil is overkill. Try to find out where the water is coming from and divert it from going under the house.

Gary, thanks very much for your help. I understand from the crawl space guy that there is no specific area from which water is coming into the crawl space. He said it is just all the over the house due to the water from the yard. Is that possible? You mentioned vents to the house, I wonder if there is not enough ventilation in the crawl space because some years ago, we changed all the vents from those chicken wires to the thick vents similar to the vents used in cold air return (if you know what I mean). As a matter a fact, these vents have smaller spaces between the slats. The reason is we had a racoon go underneath the house with her young ones by breaking the vent wires. It took us a month to get the racoon out with the help of Animal Protection Agency. Subsequently, we hired a contractor who suggested these sturdy vents to prevent any more intrusion to the crawl space. Do you think the extra moisture underneath the house were the results of these type of vents?

From my classes with Howard, I like his opinion of non vented crawl spaces and their ability to maintain a constant humidity and the rise of humidity associated with vented crawl spaces, up to 100% humidity, even with a moisture barrier over the soil.

Yeh Perry, it's a problem for sure. In some areas, it's code to have foundation vents. But I can see in some locales, that the vents would allow very moist air in. It almost would make sense to staple the barrier to the undersides of the joists, once dry. In this lady's case, since she is not removing the source of the moisture, venting makes sense. But if one removed all moisture from the crawl space and were able to keep it dry year round, I can certainly see the arguement in favor of ventless crawl spaces. There are such houses and they use the crawl space as a plenum (a cold air return) in the HVAC system. The earth is often covered with concrete.

Gary and Perry, looks like encapsulating the crawl space may not completely solve my problem. Should I close all the vents to the crawl space? I live in California, I wonder if that is code. I had hardwood floor in the previous home, which is 40 years old. I lived there for 10 years and had no problem. It also has a crawl space but looks like has wider wired vents. Any other suggestions?

moisture is coming from an outside source some potential sources are:
1. poorly graded lot
2. clogged gutters and or downspouts
3. humid air
4. leaky pipes

Does the floor cupp more during diffrent times of the year?

Hi Kevin, I know my home is sitting on filled land. There are no leaky pipes, the gutters are cleaned annually. The house is always cool...I thought it was because of good insulation. It seems that the cupping is the same all year round, tho, I have not really paid much attention to it. Maybe I should wait and see if it cups less in the summer. What would that mean?

Wood cupps when its wetter on the bottom than on the top. Try this for a example, take a one inch stip of paper and lay it in a small puddle of water and watch it pull itself away from the water, same thing happens with a wood floor. Right now I would imagine you have been running the heat some, by doing that it often dries the interior of the home out your flooring included. Does your home sit in a low spot in the yard? I had to put a french drain along the backside of my house to divert the water coming off my neighbors yard to fix the problem under my house.

I don't know much about this but is sounds like the soil is either compacted or a type that does not drain well, like clay. If that is the culprit would some type of forced ventilation help any? My front yard is always damp in places the where the sun never hits.

Kevin, I don't think the house sits on a low level of the yard. The driveway and the front yard slope slightly upward toward the house. The backyard has a pool, so I would think that's level, altho the yard towards the right of the pool has a man-made small mount, the left side is leveled.
The crawlspace guy said there is no need for a drain pump nor ventilator. He does not see any leakage or drainage problem. Could replacing the vents with wider holes help some? Or encapsulating the crawlspace by attaching the plastic above the vents? And how long should I wait until I can resand the floors?