My 20year old house has a porch on the second floor supported by 4x4 cedar
posts that stand on a concrete foundation porch on the first floor. I've
just discovered that the cedar is rotting out where it comes in contact with
the concrete. If fact, I think the wood has compressed some allowing the
porch (and the roof above) to lower up to 1/4". Now I have to replace these
supports. My friends debate on whether to use 4x4 cedar or CCA pressure
What do you think? Any other tricks or suggestions as I get into this
project. I plan on renting some support posts, using a bottle jack, etc. to
get the old posts out and new ones in.
Check the existing posts for extent of rot. If, in the
unlikely prospect, you can cut off a small section and
reseat the posts in metal post anchors of sufficient height,
you may save yourself some work and a few bucks on new 4 x
4's. Worth checking.
I agree with Jim. Unless the posts are in general disrepair, why replace
them. Use either some one of the patented metal bases which are designed to
keep the bottom of the post off the concrete and thus prevent the problem
you do have, or change out to CCA or artificial wood plinths at the base of
Keep the whole world singing. . . .
The important thing is to not let the posts come in contact with the
concrete which holds moisture and causes rotting. A proper post base
between the concrete and the post is needed to prevent this.
Any type of wood will then do provided it is properly protected. If left
natural, cedar or redwood stands up well. If painted or stained regularly,
regular construction-grade wood is fine (Spruce/Pine/Fir around here).
I would steer clear of treated pine posts unless you are really fussy and
select only the best. If your pine 4x4's are anything like ours, as soon as
they see a bit of sun they'll warp and twist ( a friend had his veranda roof
pulled down several millimetres by this).
As has already been suggested you may be able to rescue the existing posts.
Have you considered galvanised steel posts? The prices aren't much different
from wood (well, here anyway).
Simpson makes a line of post bases that attach to concrete and space the
bottom of the post above the concrete to prevent rotting. I've seen
them sold at Home Depot.
Cedar is not a particularly strong material. What I have done in my
home is to use 6x6 SPF posts and in some cases posts made by laminating
2x6s while staggering the joints by as much as 8 feet. I then wrapped
these posts in 1x cedar for appearance. My posts extend three stories
so I used 6x6 and 8x8 posts. For a shorter post 4x4 may be adequate.
The loads will determine the cross section.
More recently I have used synthetic square posts (wood strands laminated
with glue) and I like these most of all. They are stable (no bending or
twisting) and can carry a much higher load than cedar.
Can you cut the posts in place and splice a replacement portion below
the cut, possibly laminating 2x lumber on 4 sides for strength? This
could then be wrapped in cedar for appearance. You'd end up with a
larger cross section post below but would not have to remove the post
where it attaches to the 2nd floor porch.
If the rot really is confined to the bottom edge of the posts, I'd
consider cutting off an inch or so and replacing it with blocks of
treated lumber with the grain running horizontally rather than
vertically. This will prevent the blocks from wicking moisture up into
your cedar posts and also the treated blocks should last a long time and
then can be replaced again if need be. This obviously looks better if
the posts are painted rather than stained, but with a little machining
around the edges, the treated blocks can almost be made decorative as
well as functional.
That may not be the case. It could very well be that the porch was
built with a pitch to the outer edge. If you try to raise it 1/4" you
may damage the roof where it intersects the building.
When you set the new posts, you should leave the pitch and elevation as
If it ain't broke, don't fix it . . . especially true in old
houses. You as often as not do more unintended damage than
intended good . . . often for a condition not discernable to
anyone else or to actual utility.
Lots of "declining conditions and/or wear and tear" aren't
that at all but are deliberate, original techniques taken in
the absence of then-existing alternate techniques or taken
to address conditions that are all too often today just
I'd use what matches the porch, but either will work. Personally, I'd
pick cedar just to avoid the nasty pressure-treated sawdust. Buy a
metal post bracket that attaches to the concrete and attaches to the
post. This bracket keeps the end-grain of your post off the concrete
and dry. You'll need a concrete bit and lag bolts.
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