If
the siding on your house is rough-sawn cedar, then my personal
preference would be to use similar rough-sawn cedar 1x4 for trim. This
lumber is available at many lumber yards. I can't remember if I've seen
it at Home Depot or Lowes. Preserving the rough texture would be my
highest priority, if the siding is rough.
If the siding is smooth, then you could
use any type of lumber. Pressure-treated Southern Yellow Pine (almost
all that treated stuff is SYP) is not everyone's favorite for trim
because sometimes it warps badly. But if held with enough nails (and
long enough nails, 1 inch penetration into the framing) it should stay
in place.
You could also use any clear and
straight softwood, pine, spruce, fir, etc. For many people the price of
the wood drives their decision. But any wood with knots will have a
tannin bleed-through problem if covered with a light-colored paint or
stain. Unless, that is, you first spot-prime the knots with Zinsser's
B-I-N Primer Sealer. It's the only product I know of that keeps the
brown tannin spots from bleeding through.
You mentioned that your house is 20
years old and has painted cedar siding. Is it possible that what's on
the siding is solid-tone stain? Around here there are hundreds of houses
with rough-sawn cedar siding, and while some appear painted, they are
actually covered with solid stain. The benefit of solid stain is that it
does not flake off over time, but it just sort of fades away.
Last summer I "painted" a
large house with a solid-tone stain. It was a product called Rubbol made
by Sikkens, and it is supposed to last about 15 years. We did the trim
(all made from rough-sawn cedar 1x lumber) in white and the clapboards
in blue. It worked quite well.
The point I'm getting at is: the choice
of wood may be less important than the choice of finishes. Whatever you
choose (which should match the texture of the siding), you will be best
served by priming the back and all sides of every piece of trim. I have
read a lot lately about the benefits of "back-priming", which
deters moisture from getting into the wood from behind, from the sides,
etc. You should also carefully caulk all the way around the window trim,
between the end of each siding clapboard and the trim. This does not
take that long to do. I use a siliconized acrylic-latex caulk such as
Alex Plus. There are other products that are stainable, which is
important if there is not a color of caulk that matches your finish.
You also might find some helpful people
at a local paint supply store... the kind that caters to professional
painters. I've found employees at some of these stores to be very
knowledgeable.
Also, make sure that the window
installers carefully install flashing around the windows (if you are
using windows with a nailing flange) to ensure that stray rain does not
get behind the window and damage the framing.
Bruce W. Maki, Editor.
