I recently purchased a Protimeter BLD5365 Surveymaster. Today, while inspecting a brand new home in South Florida, the Surveymaster indicated that all tiled floor was wet. This cannot be a plumbing issue, considering that all supply lines are overhead (Pex), and the only water lines below the house would be drain lines (which have not been in use). This occurs in both the bathrooms (porcelain/ceramic tiles on thinset) and the main livable space (3/4" white marble on mud). This does not occur in carpeted areas. Would this be the thinset and mud that is still curing? The reading on the Surveymaster is relatively consistent in all areas. It was red and beeping rapidly - and I think between 300-450. The floors were probably put down 1-3 months ago.
I’m not a big fan of moisture meters that say WET or DRY or whatever else and I shut off the beeping feature on mine. I just find that distracting.
I just want to see a number and I keep in mind the numbers are relative.
If I’m checking an apparent moisture stain the client will sometimes ask, “What number are you looking for?”.
I tell them I’m not looking for a particular number as it’s all relative.
If I using my meter on an interior section of drywall with no moisture issues I’ll get around 7%- 10% or so.
If I place the meter on an exterior cold wall in the same room it will typically display a higher number.
If I place it on an interior plaster on brick wall exposed to the exterior it will register a much higher number.
So I consider each reading to be relative to what is around it.
Stephen asked the right question, if this is tile on a slab you’ll see a much higher reading than if the tile were over 3/4" ply and hardibacker for instance.
I would suggest before using it for reports you just get to know it, take readings on lots of different surfaces. You are essentially interpreting the numbers and to do so you need to really know how the tool responds in different situations/environments.
I have noticed my SurveyMaster will falsely show some tile as wet and I also seem to get a blip when passing over a nail or some other metal object under the drywall. I thinking some tile may contain minerals that cause this to happen. To verify I just check the tile in an obviously dry area for a sanity check.
Thank you for the replies, everyone. The tile is on the first floor - slab on grade. It shows the same consistently high reading all over the marble in the common areas and porcelein tile in the bathroom. It does not read high on carpet. Could it be that this is occuring because the marble and procelein tile are VERY reflective (marble shined and polished, and the porcelein tile is very shiny)? Could the signal be reflecting off the tile surface? I am doing the test in REL mode.
I have done some internet search on the subject since my last post and besides nails and metal drywall beads there appears to be some heavy metals in the glazing compound used on some tile, especially any foreign made tiles (lead and chromium). It appears the glazing compounds may be the main cause for false readings, however I can not rule out iron oxide that gives clay that red color found in some tiles.