Can fresh paint cause excessive indoor humidity?

I am a project manager for a construction company. A few condos in a project we built have excessive indoor humidity with no obvious moisture source. One unit in particular was recently completely repainted. This unit (and one next door sharing a common party wall) have relative humidity in the 75-85% range. Could painting the unit (about 1000 sq./ft.) with the doors and windows closed be the cause of the high humidity in this unit? How about in both units? Could the moisture from the painted unit leech through the party wall and cause excessive moisture in the adjacent unit? Any help would be appreciated!Can fresh paint cause excessive indoor humidity?
Most paint these days are ';water-based'; and have upwards of 65% water. When applied to surfaces, some of it can be absorbed by the surface but most of it will evaporate into the air. Painting a wall will definitely raise the humidity in an unventilated, tight room. Considering the other substances in paint that vaporize while the paint is being applied and drying, you should have plenty of fresh air, not closed doors and windows.





Another problem is that the perm(eation) rating of the paint and/or underlying material is incorrect for the type of conditions in the room. If it is too low, the water vapor cannot escape. If the moisture is coming from the painted surface up through the paint, the pressure of the water vapor can break the adhesion of the paint film. A few links below about perm rating.





A lot of paints do not state a perm rating on the can. Either you have to ask the manufacturer, or the perm rating isn't known.





Moisture can go through wall materials and through paint film. It may have happened in your 2 neighboring units, but you'll need to consider other possible sources of the moisture, too.





Good luck with your future painting and construction work!Can fresh paint cause excessive indoor humidity?
sound like the unit is too tight for the humidity inside to escape. no where for the excess humidity to go. crack a window, run exhast fans hope this helps





Be Blessed!
i always turn the AC up high to dehumidify the area I am painting. It helps the paint dry faster. sounds like your unit is rather well sealed and that may create some of your problem.
Turn on the AC! It helps out drying time. Sounds like units are to tight, this is going to lead to sweating inside of the walls, and mildew. Need to put in some vents somewhere.

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