Siding moisture check before you paint
Paint over damp wood is the most common reason exterior jobs peel in western Washington. Plug in a reading and see what we would do.
Dry enough to prime and paint
Not sure how to read your meter, or no meter at all? Call (253) 478-2745 and we will test the walls during the walk-through.
How to take a good reading
Use a pin-type wood moisture meter set to the species if it has that option (cedar reads differently than fir). Take readings in the morning after dew has dried and again in mid afternoon, and always test the north side and the lowest courses, where water sits longest. The highest number you find is the one that counts.
A dry reading on the sunny side tells you little about the shaded side. On many Tacoma houses the south wall can be ready a week before the north wall, so we often paint a house in the order it dries.
Why the numbers matter in western Washington
Our wet season soaks siding for months. Even after a dry week in June, wood behind lap joints and at the bottom edges can still be wet. Paint seals that moisture in, and when the sun heats the wall the water pushes the film off as blisters. Waiting for the reading costs a few days. Painting too early can cost the whole job. See our exterior painting and cedar siding staining pages for how this fits into a full project.
Moisture meter questions
What moisture reading is safe for painting wood siding?
For cedar and plywood siding we look for about 15% or less, and about 12% or less on pine or fir trim and window parts. Readings near 20% or above mean the wood is still holding water and paint applied now is likely to blister or peel.
Where on the house should I take readings?
Test several spots: low on the wall near the ground, under eaves, below windows and on the north side, which dries slowest here. Push the pins in across the grain on bare or lightly coated wood and take the highest reading as your number.
Can I use a moisture meter on fiber cement siding?
Pin meters are made for wood, so their numbers on fiber cement are not reliable. For cement board we go by touch and time: dry surfaces, dry bottom edges and at least a day or two since the last rain before priming or painting.
Want us to test your walls?
Call and tell us what you are painting. We answer 24/7 and set up a walk-through at a time that suits you.