Wood Stair Meets Wall Stucco Problem
These wood stairs look like they where built after they finished
the stucco. The main problem here is the wood touching the
stucco can absorb moisture and this could lead to wood rot
damage. The
problem gets worst if the ends of the wood treads and risers are
not painted.
Paint can provide a water resistant and sometimes waterproof barrier, but
this won't solve your problems all the time. Keeping a small space between
the two will be your best bet. I've seen paint under these conditions
separate from the wood, for a variety of reasons, making it difficult to
create some type of separation that wouldn't allow moisture to absorb into
stair treads or other parts of the stairway.
This problem could have been prevented with a 1/2
inch space in between the wood and the stucco. This will allow
air to circulate between the wood and the stucco allowing the
moisture to evaporate faster.
Here's an architectural section that might provide you with a little more
insight on this particular problem. The black arrow is pointing to a small
gap between the wall stucco and wood stair parts.
Any amount of
debris that actually gets trapped in between the wood and stucco will only
add to the problem and it's only a matter of time before dirt and particles
of leaves get trapped in this area, providing a bridge for moisture that
accumulates in the wood or stucco, to transfer back and forth.
Another problem will be that the area in between the wood and the stucco can
remain moist for long periods of time, without direct sunlight or higher
than normal temperatures, allowing it to dry out. For example, the visible
areas might look dry, but the areas that can't be visually examined, might
not be, allowing moisture to remain in these areas for longer than normal
periods of time.
The bare minimum gap for something like this would be a half-inch, but I
would like to see at least one inch and this area will need to be inspected
regularly to make sure debris isn't building up in between the wood stairway
and the exterior stucco wall.
It won't do you much good to have a 1
inch gap filled with debris, allowing moisture to travel back and forth from
the wood to the stucco.
A recommended maximum distance for something
like this would be 2 inches, even though you could probably go up to 3 7/8
inches, but that could be pushing it. Don't forget to validate this
information by checking with your local building department officials to
make sure your stairway meets local building codes.