Floors buckling; where could the excess moisture be coming from

Q: Six years ago I had a wood floor installed in my 2nd story. I now have floors buckling. The buckled floors are on different planes in each room. After the floors started buckling, we had over 10 inches of rain. This did not cause additional buckling so I do not think it is a roof problem.

Any suggestions?

A: Well, there is nothing above the floors on the second level but the roof. Likely suspects: the roof, either toilet, sink or tub/shower on the second level or a second floor laundry room. It sounds like we are talking about a significant leak, not just a localized trickle. Anything happening on the main floor? Stains in the first floor ceiling?

Follow-up: No stains on the first floor.

Similar Q: We have a rental house in Corpus Christi, TX that is 85 years old, pier and beam and with oak? floors. We recently had the house re-roofed, put on vinyl siding and new windows (Feb/March). In August our tenant informed us that the wood floors were buckling up to 6 inches in some areas. This has never happened in the 16 years that we have owned the house. Our siding guy says the house is properly vented and he fixed a long-standing leak from the bathroom that was draining under the house. The tenant runs the AC at about 70 degrees. There is no dehumidifier. 3 Flooring guys have come through and nobody has figured out the problem or offered a solution except to re-finish the floor with a more permeable/porous coat and then to fix the damaged wood with no guarantees. We are trying to take care of this from a distance and don’t know what to do. Any thoughts?

A: Clearly this is caused by excess moisture coming from beneath the floor. You say there was a previous leak which was draining into the crawl space beneath the building. My thinking is that is the likely source of the problem. If it is just dirt under there you may want to consider laying down a tarp, plastic or some other membrane that resists moisture transfer. Did anyone check the moisture content of the wood flooring? Sanding is really out of the question until the pressure on the floor is relieved, meaning it has dried out to an acceptable range of 7-9% moisture content. You might also contact the National Wood Flooring Association to see if they have a certified inspector in your area who can come and give his assessment.

Follow-up Q: Thanks so much for getting back to me. There is no inspector in the area (I checked the website). We plan to relieve the pressure (short term floor fix) and try to increase the venting underneath the house and then fix the floor once the moisture contents are lower. There is just dirt (it is a crawlspace) under the house. Our flooring guy suggested a fan and some other means to try to increase the venting under the house. We are also planning on looking at tarp/plastic under the house as well. I was just wondering if you thought that there was a possibility that the siding, roofing and window work created some sort of change in environment that would adversely affect the floors. Have you heard of that happening before? The house is likely a lot more insulated/air tight than it was before.

A: It seems logical to me that if the house itself is much more “air tight” it could contribute to problems if there is excess moisture and no means to control that moisture. The cottage I’m working in this week has concrete block foundation with a crawl space and dirt floor. It is built on a hill and there has been a lot of work ongoing to moisture getting in to that space. Two guys were down there today to lay a very heavy gauge plastic sheet on the dirt. He says they seal the edges with spray foam so no moisture can come through the plastic into the space. The oak floors above were slightly cupped but nothing near the situation you face.

Having a well insulated and sealed house is a good idea in terms of comfort and energy savings. But we still need air exchange or else the indoor air quality will drop. It’s out of my expertise, but I do believe there are air exchange systems for highly sealed homes. Adding house plants would likely help a lot in keeping the air clean. Won’t help with the moisture issue though.

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