Moisture meter reading

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Old 12-17-06, 04:41 PM
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Moisture meter reading

I had an installer over with a moisture meter and he did a moisture test in several areas of my house. He said the reading is "13-14" and that it was normal (he was trying to find the cause of problems with my existing hard wood floor). He also said that he would happily install hardwood for this kind of moisture reading. In fact he claimed that he just did an install where the moisture reading was about 13-14 (same as mine). I believed him.

Today I spoke with another installer and I mentioned to him the moisture reading in my house. He said it is way too high. He said the reading should be 3-4 for a trouble free install.

Obviously one of them doesn't know what he is talking about. Who is right?
 
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Old 12-17-06, 06:29 PM
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OK, without seeing the meter readings myself, to know if they are speaking % or what.

14% is too high!!!! 4% is too low!!!!


A hygrometer, tells the temperature and humidity. That will determine what the woods moisture content should be at that humidity.

30%rH = 6.2% MC
40%rH = 7.8% MC
50%rH = 9.4% MC
60%rH = 11.1% MC
 
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Old 12-18-06, 06:59 AM
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Originally Posted by Carpets Done Wright View Post
A hygrometer, tells the temperature and humidity. That will determine what the woods moisture content should be at that humidity.

30%rH = 6.2% MC
40%rH = 7.8% MC
50%rH = 9.4% MC
60%rH = 11.1% MC
Thanks but could you please explain that a little more? I knew I was missing a scale (or units) when I spoke with the second installer but he said he doesn't know what the scale is and it is commonly referred to by just the number.

A hygrometer is what I have in my house that measures relative humidity. What is the little thingy that the installers carry (pointy end goes in the wood) to measure the moisture content? Is that also called a "hygrometer" (since it measures water content)??

As for the table above, are you saying that the wood's *acceptable* moisture content varies with varying relative humidity? That seems reasonable. And in that case both of them were right. In other words, when the first installer came (during summer) the relative humidity was more like 70% and the reading he got for moisture content (13-14) was acceptable at the time.
 
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Old 12-18-06, 07:55 AM
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The installer didn't know the moisture content(MC) chart??? It is his job to know it exactly and like me, if they don't have it memorized, they better have the chart to refer to. I see lots of installers that have a moisture meter, to show the guy they subcontract from, they have one. Now, as for them knowing how to use it and decifer the information it reads, is another matter. A lot of installers use the meter as smoke & mirrors, and have no clue what they are looking for.

Good you already have a hygrometer!!!!!!!!!!!! What does it read as far as humidity?

The pin thingy, is a pin-type/probe Wood Moisture Meter. It reads the moisture content of the wood, when stuck with the grain, in a %.


Wood being hydroscopic, will swell as it sucks in moisture, as will it shrink as it dries and loses moisture. Humidity is moisture, in vapor form.

70% humidity inside your home??? that can't feel good, nor is it acceptable for wood flooring to be installed. The interior of the home needs to be maintained between 40-60%rH, or your going to have serious concerns with movement, not only in your floor, but all the wood in your home.

Outside humidity should have no effect on the wood flooring inside, except for the high humid air entering a cooler crawl space, which will escalate the humidity in the crawlspace. The crawl space must be a minimum of 18" to the bottom of the floor joists, and the soil in the crawl space covered with a heavy duty plastic moisture barrier, and sealed at the seams. If humidity levels in the crawlspace with all these measures taken place is above 60% the joist and the subfloor will have a high MC reading. If the interior of your home is 40% and the crawlspace is 80%, your going to get a cupped floor fast!!!!!!!!!!! Cupping is an imbalance of the woods MC from the top of the board(dry) to the bottom of the board(wet) The bottom of the board has swelled, but the top of the board hasn't so it curls, known as cupping.

If this is the case, a sealed and dehumidified crawlspace is in order.

Same goes for basements and their know escalated humidity levels.
 
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Old 12-19-06, 04:04 AM
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Originally Posted by Carpets Done Wright View Post
Good you already have a hygrometer!!!!!!!!!!!! What does it read as far as humidity?
Right now it is 35%. But I have had it for a year and in summer I have seen it as high as 85% (before I got the central AC) and in winter as low as 20%.

With the AC, the rel humidity comes down about 10% within 10 minutes. But after the AC shuts down, it comes right back up and stays up until the AC starts again (which can be a while). So I am not sure how I can control the humidity. I have had a dehumidifier running. It only brings it down about 10% too (and slowly).

When I tell these values to the installers, they say they it can still be done. All of them are telling me they will install Engineered or Laminate and I will not have any problems for years.

Originally Posted by Carpets Done Wright View Post
If this is the case, a sealed and dehumidified crawlspace is in order.

Same goes for basements and their know escalated humidity levels.
I understand most of what you said applies to solid wood. I do not have a crawlspace (house is on concrete slab) and I am looking at Engineered wood or Laminate as my only options. Do we have as many moisture problems with these as solid wood?
 
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Old 12-19-06, 07:21 PM
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Concrete!!! Why didn't you say so?



Concrete moisture levels cannot exceed 3# per 1000 sq.ft measured by a calcium chloride-dome test(3 are needed and then averaged), or 4.5 on the upper scale of a TRAMEX concrete moisture meter.

Your going to get face checking(cracks) if you let the wood get below 40% humidity.

Above 60% you may get end peaking of engineered.

I agree engineered wood is the way to go, over concrete.
 
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