Pinless moisture meters?

[RhinoWW]

I am a hobbyist woodworker and have a pinless moisture meter I use when buying rough lumber from folks on CL. It's always interesting to know when the wood Moisture content does not jibe with the description. I typically take a block plane with me so I can get a really good seating against the wood - but then again a few percentages can make a difference in wood movement (and measurements).

I'm about to go take a look at a trailer and will be probing with an ice pick for soft spots. Another thread on a probe type meter got me thinking - has anyone used a pinless moisture meter during a trailer inspection with any reliable results? I'm not looking for precise moisture content, but just a heads up of a leak/no leak, so a flat exposure to the wood in theory is not as important.

I know it will be below freezing when I take my first look, but it has rained and snowed a great deal recently, so there could be some water if there is a leak.

So, has anyone used a pinless moisture meter with any reliable success during a trailer inspection?
thanks.

[dkottum]

I use a probe type meter to regularly check mine for leaks. Not sure what trailer you are looking at but nearly all have a vinyl floor covering over the plywood subfloor. Some have carpet areas. I think the pinless meter has to come in direct contact with the wood (?) and if so would not work.

[DaveFL]

Used a pinless for f/g over wood checking moisture content, works. Not exact percentage but shows changes or differences over an area, start with a number on a dry sample section and compare. You might get the answers you want by using an IR thermometer, cheaper and can show temp differences if saturated with water compared to dry sections away from leaking windows or panels.

[NevadaGeo]

In soils inspection, we find that frozen soil really acts funny with our nuke gage moisture readings. It'd be interesting to hear if those wood moisture meters also are affected by frozen HOH.

[idroba]

It is interesting that I just was going to post something about this meter type.

Tonight I was at Costco and they had a set of a 1) pinless moisture meter and 2) an infrared thermometer, complete with battery for each for $35 total. It is Costco item # 687286. I fell for it, as my IR thermometer has gone bad, and the price was right. I was curious about the moisture meter for sure.

I opened it up and have been playing with it, but really have nothing to test it on. The instructions on the moisture meter are interesting in that they say that really it is a relative device, not to take the specific moisture % too seriously, yet in another place state that on hardwood the accuracy is 4%. They say it uses a capacitance effect system to measure. There are settings for Wall (drywall seems to be what they mean), Masonry, Hardwood and Softwood. It is unclear if it really can measure moisture content through another material such as the vinyl flooring over the plywood floor in my FC 20'. But if it is relative, and will scan through vinyl, who cares about the specific numbers? If it will indicate dry here and wet there, that is very valuable information. The instructions say it works best on 3/4" thick samples, which is close to the floor dimension of the Airstream.

So, right now I don't know what to say or think. I don't have anything to test it on where I know there is wet wood and dry wood.

The IR meter works fine, like others I have seen or used, but the moisture meter is yet to be evaluated in a real situation.

I hope others will buy a set and maybe have a wet and dry area of flooring in an Airstream to test the moisture meter on. I may have to create a test sample, especially one with a vinyl flooring top.

The two for $35 is low enough price to try them out.

[idroba]

A follow up on the no probe moisture meter I recently got at Costco. BTW, the set of the moisture meter and IR thermometer is now on sale for $28, not the $35 I paid. Sigh.

To test the moisture meter (MM) I took a 12" x 12" piece of 3/4" plywood and purchased one 12" vinyl floor tile. I then did tests using the softwood setting on the MM. Each time the tile was hand held over the plywood. I did not use the adhesive to hold it in place. The measurements were made in the Phoenix AZ area where it is very dry. I winter here.

Test 1: Dry plywood measured through the tile.

2 to 4% indicated on scale.

Test 2: Dip in water, surface wet wood not dried off, through tile.

Depending on where measured 22 to 45% indicated on scale. Water dripping off sample.

Test 3: 5 minute soak in water, then surface dried with paper towels, tile in place.

Edges 20 to 25%, center 15%

Test 4: 30 minute soak, surface dried with paper towels, tile in place.

Edges 35 to 40%, center 25%

Test 5: 1 1/2 hour soak, surface dried with paper towels, tile in place.

Edges 50 to 55%, center 35%

Test 6: 3 hour soak, surface dried with paper towels, tile in place.

Edges 53%, center 47%


Test 7: 3 hour soak piece allowed to dry for 12 hours. All sides air exposed.

Edges 16 to 25%, center 6 to 7%.

Test 8: 48 hour dry. All sides air exposed.

Back to original 2 to 4% reading.


Conclusion: The MM will read moisture changes in plywood covered with vinyl quite easily. I will be very interested to measure the floor in my Argosy and Airstream when I am back home. They are stored under roof, so they get no snow or rain on them, but all sides and bottom are exposed to winter air.

It looks like this will be a good inexpensive tool to easily measure if your plywood floor is wet, and subject to rot, either on your own trailer, or one you might purchase.

[dkottum]

I use a meter that probes through the vinyl into the plywood subfloor and I know it works. If I don't probe through the vinyl, wet subfloor will not move the needle. I know because I've had wet subfloor in four different locations.

What kind of sensor is able to sense moisture through the vinyl surface? Doesn't seem possible. That's a pretty small test area; could you simply be reading moisture of the surrounding air rather than through the vinyl? Moisture meters are quite sensitive. I'm a skeptic.

[idroba]

You are welcome to be a skeptic. When I can measure the difference between the moisture at the cut edges of a 12" square panel and the center (which takes more time to get wet) I don't think the size of the sample is too small.

According to the information provided with the meter it works on measuring the capacitance of the sample, so it is an indirect measurement.

All I want to know is if the plywood under the vinyl is wet or not. The tests I ran show me that the meter will tell me that very well.

[RhinoWW]

My question was really to see if a pinless moisture sensor could give any useful information during an inspection. The answer is yes, particularly if there has been rain or melting snow in the relatively recent past. Not likely to give much useful information in AZ in the summer, as even the rotted wood will likely have a low MC.

Thanks for the follow up. Very interesting and informative IMHO. One of the many reasons why I find this forum to be so valuable as I look for my next purchase (and hopefully not money pit).

FWIW, the trailer I went to look I unfortunately did not need to use the moisture meter. I could see some of the bare plywood and see it was water stained and actually wet. The ice pick probe showed lots of soft flooring. I made an offer that was higher than it should have been - good thing the seller passed.

[DKB_SATX]

Originally Posted by RhinoWW

~~
FWIW, the trailer I went to look I unfortunately did not need to use the moisture meter. I could see some of the bare plywood and see it was water stained and actually wet. The ice pick probe showed lots of soft flooring. I made an offer that was higher than it should have been - good thing the seller passed.

Been there, dodged the same bullet, expressed the same sense of relief. I'm still not sure why I offered 1/3 what he was asking, which was 2x what I think it was worth, but I sure am glad he didn't take it. The much-better money pit I found months later offends my financial sensibilities enough as it is!

[RhinoWW]

Indeed. Waiting for return emails on new money pits with potential.