Jim Decker

Marc you are absolutely correct every area of the country has different levels of moisture that are acceptable. In the case of too much the answer is a dehumidifier here in El Paso generally a humidifier will correct these problems. We do a lot of Sand and Finish work and advise customers if they don't want the wood filler we use to fill gaps they had better keep their humidity parameters between 30% and 50% here. When ServiceMaster is called in on flooded homes the first thing they do is apply heat, hugh dehumidifier and air movement to dry things up. Unfortunedly Plywood over concrete and nail down hardwood will never dry up even after a year, oh yeah I am sure someone will state they have seen it done, BUT experience dictates removal and replacement as it is unrealistic to wait and year and then find it won't do it. Once water saturates plywood in this situation 15% to 99% noted it can produce mold and you know how excited people get about that. Good comment though. Jim

I can only relate to this regarding hardwood installations. I am a wood inspector with the National Wood Flooring Association. 1. Is the grading sloped away from the house. If not it needs to be. 2. The crawl space needs to have a minimum 18" spacing from the dirt to the joists and covered by 6 mil poly secured up the wall. 3. Most building codes require that crawlspaces be vented to the outside and have 1.5 square feet of venting for every 100 sq ft of crawl space. 4. Have read of some inspectors testing for humidity levels in crawl spaces reading 98% and water running down the walls and pooling as described. Humidity testing should show a maximum of 50% or less or do not install hardwood until this is achieved. Trust this helps. Jim

As a certified hardwood inspector with the NWFA I can tell you you need to do the following. 1. The grading must slope away from the house. If this is not feasible install a french drain. Imperative! 2. Get someone with the proper tools and knowledge to assess the crawl space, the subfloor and the hardwood for moisture content, humidity and temperature try http://www.woodflooringinspectors.com/ for an inspector near you. 3. Does the crawlspace have adequate vents to the outside and do they adhere to local building codes? 4. Definitely the ground should be covered by 6 mil black poly taped up the wall. 5. Every box of hardwood has the manufacturer's installation guidelines along with warranty and maintenance guidelines. Not adhering to these will void any warranty with the mfg. 6.Temperature and humidity levels must be between 60 degrees to 80 degrees f and 30% to 50% humidity levels excessive humidity will cause cupping.Even if unoccupied!!! 7. Acclimation not properly adhered to can cause permanent cupping which can only be fixed by a sand and finish IF the subfloor moisture content is less than 12%. And the subfloor and solid hardwood cannot have a difference of more than 4% for 2 1/4" or more than 2% for 3" or wider. If this occurs the cause must be determined before continuing. I cannot stress enough to follow manufacturer's guidelines. It distresses me to see what consumers are subjected to regarding nailing schedule, proper subfloor, proper spacing at the walls, inferior adhesive and general lack of installation knowledge by installers. If yours does not have a moisture meter find one that does or you will never know when it is proper to proceed.The installer will need one capable of testing concrete as well as the hardwood. Most only do one or the other. 8. Subfloor over concrete is always plywood cdx exposure 1. 1/2" by NWFA guidelines though most mfg require 3/4" and always adhere to mfg guidelines.