Driving around today I saw something that made me wonder,
why is it that pressure treated wood is used wherever it is in contact with concrete or blocks?
Why is it when they make an exterior arch (over a window or door or wherever) on a concrete house “they” use non-pressure treated?
Things that make me go hmmmmm
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WWPD
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Replies
why is it that pressure treated wood is used wherever it is in contact with concrete or blocks?
The concrete/block foundation can be constantly wicking water up into the wood whereas the stuff up high only gets wet when rained on. So pressure treated to the rescue (or put some copper or somesuch in between) on the foundation.
Assuming I understood your ponderings correctly.
jt8
"The cynic is one who knows the price of everything and the value of nothing." --Oscar Wilde
That among other things make me wonder about all the building codes like that.
I'm in a 325 year old house that probaby wasn't ever taken care of after the first 100 years from what I can tell yet its still here isn't it?
Be trees ( with the bark still on) for joists
andy
The secret of Zen in two words is, "Not always so"!
When we meet, we say, Namaste'..it means..I honor the place in you where the entire universe resides, I honor the place in you of love, of light, of truth, of peace. I honor the place within you where if you are in that place in you and I am in that place in me, there is only one of us.
Ah yes....but those decorative wood arches aren`t structural now, are they?
J. D. Reynolds
Home Improvements
No, just thought that concrete and or stucco would always be sort of a wick for moisture. So it seemed odd that in these case it was ok to use non-pt.
I have waaaay to much time to think I suppose -----------------------------------------------------------------------------
WWPD
> concrete and or stucco would always be sort of a wick for moisture.
True. But stucco should always have a moisture barrier between it and the underlying wood. Tar paper in the old days, now that or one of the many new plastic versions. I've demoed plenty of termite damage and rot caused by incorrect installation of that very necessary moisture barrier under stucco.
-- J.S.
Stucco may be the one siding I`d select after vinyl.
We have a ton of older Tudor style homes around these parts. I`ve worked on a bunch of them over the years. I`ve yet to work on one where moisture damage wasn`t a problem.
I honestly don`t know if there is a proper way to protect against such.
Stucco is a sponge. Sooner or later the wood frame behind it is going to suffer because of it. Worst part about it is that the stucco usually holds up long after the damage has begun and you don`t find out about it until its too late.
J. D. Reynolds
Home Improvements
codes require that whenever structural lumber is in contact with masonry it must be PT. irf it is trim or cosmetic, it needn't be.
Reasons -
two
wicking from ground up to wood is one already mentioined
Sweating is another. The masonry will typically be cooler than the surronding air quite often and percipitation of water vapor is attreacted to be absorbed into the wood. If you keep a wetting cycle going on for long enough and you will see rot.
The codes do alllow for other woods to be used if separated from direct contact, say by tarpaper or vycor
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UBC does allow non-pt wood for plates and other structural uses on elevated slabs not in contact with the ground, but with the requirement that that slab be at least 3-1/2". Also, slabs isolated from ground moisture with a water barrier are exempt from using pt. From what I understand "water barrier" refers to a membrane-type barrier and not simply 4 mil poly.
How about a barrier between concrete and non-pt wood? Is that OK?
-- J.S.
How about a barrier between concrete and non-pt wood? Is that OK?
Yep. ...assuming of course that it is a long-term barrier. I've worked with people who should know better who wanted to use house wrap, which would still allow moisture to pass into the wood. Ice and water is so usefull that a roll of it is always on hand and works well for such things.
Cheers,
Don
Thanks. Then I'll go with I&W instead of the corrosive ACQ for this little gazebo DW wants. Neither rot nor rust .... ;-)
-- J.S.
Don't forget that codes merely spell out the minimum standard, not the best.I've repaired too much rot in this humid climate that is more from ( my opinion) condesation saturation than from wicking. Concrete will wick a noticeable amt, but many of these old ones here are granite base under the sill trhat does not wich as much as it creates dew points.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Good point about the wicking in humid climates. Living in a popcorn-fart state most of my life sometimes lets me forget when posting here just how hard it is to keep water at bay in other regions.
Respectfully, once again your student,
Don