Thread: moisture meter for concrete floor

somebody told me it does not make sense to test concrete ( crawlspace/basement floor) moisture 'cause it always has moisture. But I think sometimes we only need to know the relative readings. I found the reading along the perimeter is much higher than the interior on the floor of crawlspace. Can I say perimeter drain should be investigated?

Thank you

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You can say anything you want. If you want to retain credibility then I wouldn't. Putting the meter on the floor or foundation is pointless. You're below grade and soil tends to be damp/wet - it's why basements tend to be damp/wet.

If you say that the perimeter drain should be investigated are you saying that it shouldn't be wet? They're there to collect water. Put the meter away. By using it you're setting your client up for unrealistic expectations. Basements are not boats - they tend to leak and be damp - it's their nature. If the client can be made to understand that it will reduce your call backs. If the client can't accept the possibility of this then they should buy on grade construction.

I would not test any slab or concrete stem walls with just a standard moisture meter. If you do not have a high end meter for testing concrete. just state what you see. water stains or indication of moisture do not state any numbers from a cheap $ 400 Meter...

Best

Ron

Does your meter have a specific setting for concrete? If not forget it.
Basement walls will tend to have higher readings. So a question would be what are those readings higher to? It doesn't make a lot of sense. If you see an area that looks particularly dark, damp, then maybe.
Properly installed drain tile shouldn't be an issue either way.

the surveymaster moisture meter non-invasive only test to 3/4" deep. Therefore, I wonder if I found the high reading alarm close to perimeter & medium reading 2 feet away. can I say perimeter drain could have some blockage or crushed section?

Originally Posted by Peter louis

can I say perimeter drain could have some blockage or crushed section?

Anything "could" have anything.... the previous advice is good.... filling people's heads with all the "could be" scenarios is a quick path to the exit door of this profession.

I do a whole lot of critical analysis in my reports but I would NOT say that.
As I was taught, "You write what you see". I doubt you can see that.
If you want to write that you are concerned about conditions but NOT your SPECULATION on the drain tile. You are asking for trouble.
No offense but how new are you? Just curious

Originally Posted by Markus Keller

I do a whole lot of critical analysis in my reports but I would NOT say that.
As I was taught, "You write what you see". I doubt you can see that.
If you want to write that you are concerned about conditions but NOT your SPECULATION on the drain tile. You are asking for trouble.
No offense but how new are you? Just curious

Hi, Markus, I am still a trainee.

Thank you for all advice.

Originally Posted by Peter louis

the surveymaster moisture meter non-invasive only test to 3/4" deep. Therefore, I wonder if I found the high reading alarm close to perimeter & medium reading 2 feet away. can I say perimeter drain could have some blockage or crushed section?

IME, the salts in the concrete, CMU, and most other masonry make the meter see WET. When I first used a surface scan device on concrete and always got a wet to very wet reading, I contacted the manufacturer, GE. You might get variations of moisture but they always will be medium high to high. You have to go by visible evidence unless an IR device picks up a temperature difference.

I followed several experienced inspectors. They all use Survey master non invasive moisture meter to detect shower stall & tub. Some of them detect the floor around the toilet. One told me do not detect the tile floor on slab foundation because it is concrete & always has moisture.
In that Survey master non-invasive is only effective in 3 quarter inch deep. I am wondering it can only found the moisture in the mortar bed or concrete substrate not the plywood or wood frame. Also, there should be a waterproof membrane behind the plywood. Therefore, should we worry the detected moisture?
Further, this makes me think how the mortar or cementitious material can get dry in between the waterproof membrane & grouted tile.