I decided to get a better moister meter than the cheap one I found at a local tool house. The new one came in today (Extech M0200). This is still a very basic meter in comparison to what most profesionals would use. This unit will measure down to 6% for wood per the spec.

The carpet has been up in my house for a week or so now and the flooring has been in the house for 2 weeks. In boxes (no wrap) with ends open (stacked 4 high).

The original cheap meter reads at around 7~8% on the subfloor.

The new unit is at 14~15% on the subfloor and just picks up the flooring at 6~7%. I took the new meter to various existing wood locations in the house (door trim & cabinets) and got readings of around 10~12% in those areas.

I have read all the guidelines and know that the subfloor should be below 12~14% and the subfloor within 3~4% of the subfloor. I picked up a Thermometer\Hygrometer at Radio Shack today and the house is staying at 76~78 F and 50~55% humidity.

Since the existing wood in the house above floor level is reading at the top of the recommended range, is it likely that the subfloor will drop? It also dosen't look like the flooring is picking up much moisture in 2 weeks. I have about 2 weeks before the planned install.

Anyone seen similar conditions? It has been rather dry around here (SW GA) lately.

Addison2481

If your wood subfloors are that high in moisture content, it means that they are picking up moisture from below. Does your home have a crawl space? If so, that crawl space needs to be completely covered with a 6 to 8 mil polyethylene vapor retarder. This is common practice these days and is specified by all flooring manufacturers. Read this:

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

Gary,
First of all, thanks for the reply. The support on the forums has been good.

The house does have a crawl space and I put down a vapor barrier a couple of years ago (prep for future hardwood installation). I also replaced some of the vents with the thermal operating type that has larger openings. The house has a 10 x 50 covered front porch. The crawl space has an opening leading into the front porch area so ventallation should be good.

I am going to go under the house now and tape the overlapping seams. The HVAC system is in the crawl space so this does not help matters. I am considering forced air movement but this could be an issue in the summer time. We have very hummid summers (SW GA near FL Coast). The fans would pull moist air into the crawl space. I would have to design a humidity control system to regulate when the fans should come on/off.

The moisture content in the wood trim is also higher than I expected. The door trim near the top is reading around 10%. The HVAC system in our home is always on. I may install a digital thermostat for better control ability?

The new flooring does not seem to pick up much moisture yet. I read a similar post in the archives last night. That person sounded like they had the same situation.

I am going to see what wood species the meter is calibrated for, this may be at play as well?

That is a normal reading for interior trim. That is the same % my meter reads when I test interior trim.

This ia a perfect case for a sealed and dehumidified crawl space.

Venting in moist air and then cooling it with the crawl space and the humidity will spike in the crawl space no matter how well the soil is covered with plastic.

If the HVAC system was to quit in the near future, I have given thought to sealing off the crawl space (insulating block foundation walls) and adding this space as part of a new larger HVAC system. I saw some climate controlled crawl space designs described on the web for mold control issues.

I hope that it doesn't come to anything that allaborate.

Just a thought:

Is there an offset for the meter you are using? The mini-ligno meter I have states that I need to adjust by minus 2 on the reading for my hardwood and to use the stated reading for the reading on my sub-flooring.

Once equilibrium is reached, and the internal temp/humidity stay fairly constant, there shouldn't be a problem. Two weeks might not be enough though, as everything is a variable.