So I'm installing solid 3/4" Mirage in a home. My humidistat is reading the relative interior to be 63%. The subfloor moisture content is 10 to 12%. What should the ideal wood flooring moisture content be? If it reads 8% MC average, is that too dry? The answer is in my NWFA manual, I'm sure. Just cannot find it at the moment.

How wide is the product....NWFA = boards less than 3" width should be within 4% of the subfloor, 3" and wider should be within 2%.

FYI, not sure what the temp is in there, but based on the EMC chart, at 70 degrees and 63% humidity, you'd expect MC between 11 and 12 %, so sounds like the subfloor is correct for the conditions.

Ya, I think I would want the MC of the hardwood to be about 10%. I am worried however though on how the client will maintain sufficient humidity in the winter to avoid excessive shrinkage. Where are you located, Gary?

K, nevermind, I see California, but unless you're coastal I would have thought the RH would be lower than 61% unless thats new construction you are dealing with. If it is new construction, maybe some effort should be put into lowering the RH before installing the floor.

The width of the flooring is 2&1/4" and most of it appears to be straight grained. It is red oak. Nice product. This is not new construction but an old house and I am adding on to another floor that was installed a few years earlier. I did a moisture meter reading of the old flooring today and got readings of 8% and 9% moisture content. The new wood is reading mostly 8%. Subfloor is mostly10% with a 12% on occasion. The house is situated up in the hills which overlook our very large bay. The area gets morning fog pretty much every morning till it burns off in the afternoon. The winters are the same. Fog. The existing flooring has performed fine. No excessive gapping or shrinkage. I understand that the RH should be lower by about 15%. But under the circumstances, how do I tell the owners that since they can see the old floor is fine? Old floor and new flooring are the same Mirage product. I downloaded Mirage install guide and it says RH needs to be maintained from 45 to 50% RH. I guess all I can do is inform the customer that this is what Mirage says and let them know if they do not do it, there is no warranty.

Just snap a picture of your thermo hygrometer when its in the zone with a time date stamp and aome identifiable part of the house when your installing it. If you can't get the rh in the zome then blow on it first.

Most of the manufatures these days also want that Rh to be in the zone when installing as well.

What is the average moisture content of the region?
That is a good number to shoot for.

If you install it at 8% and it wants to be 12%, what could happen?


Choose wisely.

If they go from 65% in the summer, to 20% in the winter, wood flooring may not be the best flooring for their lifestyle.

Ya, cause yourself a lot of headaches latter!!


Stephen sounds versed on that practice.

I'm a devil sometimes. lol

Gary, sounds to me like conditions should be relatively the same year round in this particular location. The existing floor is performing well (apparently) and the new floor is at the same MC as the existing.
Since you are laying 2 1/4 inch oak, I personally would probably install the floor in the current site conditions. I think sometimes you have to make a judgement call based on common sense, rather than what the manufacturer;s requirements are. This requirements are generally established to protect them from any issues that might arise especially in the case of Mirage.
Mirage is the second highest use product we use, and when we submit a customer complaint to them about say, colour variation, length of boards, or anything else related to the wood, their stock response is
" we didn't make the trees, God did; take it up with Him"

Got it. The area never gets hot so AC is not required or used in this area. Their furnace is mediocre at best so I don't think it gets very warm or dry inside their home. Hard to say for sure though. Being that the existing flooring is reading 9% MC at the highest, and the wood I'm installing is 8%, I'm hoping it will be OK. I'm going to allow the new stuff a bit more time in the home to pick up moisture. I'd rather it shrink slightly in the winter than cup from compression by expanding.



According to the moisture map of the US that's in my NWFA manual, the region is 8% to 13%. The notes provided in the map say not to rely on these #'s but use your own from readings one has taken throughout the year. The average I've seen on readings I've taken over the years has been 8% moisture content. Higher than that is quite unusual.

Follow your instincts!

I see 9% here.