If the wrong fasteners (common drywall screws) were used in treated
lumber (post 2003 formula) what is the life expectancy of the
fasteners? How long before they may corrode and fail?
Thank you for your time.
PS: Answers such as "replace them" or "add to them with correct
fasteners" are not helpful. Answers such as 1234 years are helpful.
I doubt the lumber will last a century, what more a millenium...
"May" I'd guess within 6-8 months, year outside. "Will" anything beyond
that is becoming pretty certain at least some will. It will depend on
just how wet the material was. Overall, I'd guesstimate a couple-three
years tops before serious problems, again less if attempting to be
structural rather than just holding deck board down, say.
Depends on the use. Drywall screws can break immediately if the structure
is stressed. They are brittle and break easily with no corrosion.
If it is a dog house, let it go until you see problems. If it is a deck or
stairs, replace them tomorrow before company comes and walks on the
I think the closest to advice in this case would be:
If this is screws holding cosmetic trim, about 1 year outdoors. If it
is for anything load bearing, such as parts of a deck, it needs to be
taken down and started over with the correct fasteners before use. It
isn't safe starting NOW.
As others have hinted- it isn't just corrosion that makes drywall
screws poor fasteners for anything other than drywall-- They have
very little [aka *no*] shear-strength. So their inadequacy is
immediate if they are being relied upon to hold something together
that is subjected to shear forces.
Just wait until they fail and replace them a week earlier.
FWIW- I just ran across a couple sheetrock screws that had been in
some newish treated lumber for a year or so. They had just started
turning white. So if you put some in a treated lumber wall to hold
up some pictures- you should be ok for a few years.
re: How long before they may corrode and fail?
I've got "common drywall screws" in the trim of my deck for holding up
Christmas lights. They've been there for years.
I used some "common drywall screws" under my second story deck to hang
some items while I spray painted them. They corroded with 6 months.
re: Answers such as 1234 years are helpful.
Are answers such as "it depends" or "never can tell" helpful?
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