Acceptable Moisture Levels In Plaster Walls

The human hand is not able to detect moisture anywhere near the 15 threshold.

Acceptable moisture levels in plaster walls.

Any reading over 17 percent is considered to be an indication of saturation and the need to replace the drywall and to take preventative measures against future moisture buildup. Anything above 1 mc in drywall would indicate a level of moisture that could compromise the integrity of the gypsum board. Calm down 20 24 in plaster is not a problem. The actual threshold depends on the length of time the high level of moisture has persisted the source and even the type of paint or coating used on the gypsum boards.

Readings are taken on a reference scale as it is only a relative degree of dampness. A reading of up to 17 percent is generally considered moderate moisture and acceptable. There is no acceptable level of damp in plaster if you can see it or feel it with the back of your hand in your case as perry said give it more time to dry out keep the room on low heating and maintain ventilation. Compare the reading to ideal moisture levels.

Exterior walls are regularly exposed to moisture. Normal readings measure between 7 and 13 percent. Generally speaking for drywall a safe moisture content mc would be less than 1 mc. Readings over that indicate the likelihood of some free water but if there is really quite a lot of water say 35 or 60 showing on the meter for example then this needs investigating.

It is crucial not to quote these percentages as a moisture content of a wall. In severe conditions you may see higher readings of skirting 22 plaster 1 3 and brick around 2 5. Example a timber skirting which records a moisture reading of 12 air dry the plaster could be around 0 5 and the brick about 1. However older buildings may use other interior wall surfaces such as wooden paneling or plaster.

The readings the meter provides of up to about 1 on the drywall scale 20 wood are of most value since a tremendous change in conductivity occurs at around 2.