I started in the building industry in 1975. At that time, walls in the northern climates were 2 x 4, windows a standard double glaze, and 8-12” of cellulose fiber insulation in the attic. Walls had poly behind the sheetrock but not in the ceiling. Often, someone would cut slits in it to let moisture out before it was even completed. At that time, the floor joists were either 2 x 10 or 2 x 12, 16” on center, with a double layer floor system over the top. It was not unusual for the top layer to be particle board.
At one point, the direction started going to a double 2 x 4 wall along the outside perimeter of the home, staggering the studs on the two walls so the cold air had a thermal break. When this was done, the exterior wall studs went from 16” on center to 24" on center. What wasn’t known at the time is that hardboard siding was not rated for 24” on center, resulting in the siding wavy all the way down the wall. Unfortunately, this was the most popular siding at that time.
Now, there are full vapor barriers on walls and ceilings, 2 x 6 exterior walls, and lots of attic installation. The home is so tight that air exchangers had to be included to keep the air quality up in the home because the air exchange is so low. Unfortunately, the moisture still has no place to go. The air exchanger and air conditioner are not a form of humidity control. They do help, but not enough to provide adequate protection. When the average home is taped and textured, over 100 gallons of water is introduced into the environment. It only takes a fraction of this amount to cause flooring failures or cause damage behind the sheetrock.
Often when doing a pre-installation walk through, I find the humidity to be over 70 percent. At this level, flooring products cannot be brought in and acclimated. The humidity has to be brought down to what is regionally accepted in the area before acclimation. If not, doors will warp, door panels and will trim will shrink, leaving gaps in the joints needing to be puttied. Hardwood will expand and contract when the humidity drops, leaving permanent gaps in the floor between planks. It is not acceptable to acclimate flooring when windows and doors haven't been installed.
What do you do in your construction projects to address moisture issues before they become a concern? Whose job is it to make sure the moisture and temperature ranges are in line before the flooring is installed?
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