Pier and Beam - Buckling Sub-floor - Need Advice

dmanindfw

I have an older 1955 home (in N. Texas) that was completely remodeled by the previous owner (a home inspector) back in 2001-2002. The majority of this 1600 sq ft home is done in 3/4" solid red oak flooring, some of it (about 25%) is the original oak flooring. Over the last 2 years the floor has started buckling. However, it appears at first glance that it is actually the OSB subfloor that is pulling loose from the joists. Pulling off one of the crawl space vents and peering under the dining room, I can see that the OSB has pulled away from the joists about 1 1/2 to 2 inches. As of right now, I have 3 rooms that showing this buckling problem and in most cases there is a rise in the floor of about 1 1/2 to 2 1/2 inches all within 3-4 feet of the surrounding floor. It also appears as though in the case of the dining room, that the exterior hardy board siding is pushing outwards and inch or two. There is also noticable cracks occurring in the corners of these same rooms.

I had a foundation guy out about a year or two ago and he suggested that it may be due to moisture in the crawl space and he recommended installing (their very expensive) french drains around the exterior. He also said the piers and beams looked fine but that he thought there was NOT enough venting installed. There is no sitting water under the house but I suppose it does remain relatively moist.

What do you guys recommend doing in my case? Should I contact another foundation guy, a structural engineer, flooring guys??? I'm just really confused on what I should do and what you think the underlying problem is here. I obviously don't want to have to put $20K or more into this house, and don't mind doing some of the work myself to save some money where possible, I'm just at a loss as to what is happening and how to resolve. I'm thinking I at a minimum I need to install a ground covering to reduce the moisture coming into the crawl space from the ground...but from there, what?

Jim F

Here is a link to a pretty comprehensive explanation of crawlspace conditioning http://www.buildingscience.com/docum...wner_resources

For your OSB to expand that much, I can't think of anything else but moisture.

dmanindfw

Thanks for providing Jim and sorry for the delay in getting back with you. Project has been sidelined for some time.

So I have looked and I just don't have the necessary space to install a vapor barrier. I need to do something to limit the moisture down there. So aside from installing a vapor barrier on the ground, what other options exist. I was looking at the ventilations fans as an alternative, but I'm not sure this will help considering I am in Texas and experience very high humidity throughout the year.

Would it make sense to install a ventilation fan in one of the existing foundation vent locations and also create 1 or 2 openings/vents from the main house into the crawl space to help circulate conditioned air into the crawlspace? If this is a good idea, do I also want to keep some of the other foundation vents open as well or seal all of these off to ensure that I am only pulling conditioned air into the crawl space?

From a quick glance at that research document you sent, that appear to be one of the recommendations.

Please advise.

Thanks again,
D

Daniel Holzman

Much of Texas has what is known as expansive soil. This is a type of clay which is prone to expansion and contraction as the moisture content of the soil changes. The effect of soil expansion is to raise some of the piers, in some cases several inches.

Due to variation in the soil over relatively short distances, it is possible that one pier will rise, while another may rise less or not at all, which has the effect of buckling floors, causing cracks in walls, and in extreme cases causing structural failure. The same problems can occur if a slab on grade is placed on expansive soil. Similar issues occur if the moisture content of the soil varies from point to point, which can occur if for example a downspout discharges to the edge of the foundation, but no moisture gets under the slab.

The only way to know if you have expansive soil problems is to get an analysis by a qualified engineer. Typically this will involve getting a soil sample, performing a laboratory test, and conducting an accurate elevation survey INSIDE your house with a sensitive instrument such as a Zip level or a surveyor's level. This technique will reveal if the floor has risen non-uniformly, and if so this would suggest foundation issues, which can then be investigated in more detail.

I would not hire a repair company until I had an independent foundation assessment. Not that the repair company would necessarily mislead you, but they have a direct financial incentive to find a foundation problem so they can repair it, whereas your problem could be moisture in the crawlspace, expansive soil, improperly installed piers, damaged subfloor, or other problems. Best to get a disinterested professional engineer to examine the problem, write a report, and recommend a solution. Then you can hire the proper repair firm.