I have a barn I am restoring. I do not want to use pressure treated wood for the sole plate or sill plate. My carpenter would use 4 x6 locust at 12 foot lengths, but we cannot find any.

Can anyone suggest an alternative? And if so, what kind of moisture barrier would be necessary.

We are not going for code regulations here. So I am open to suggestion. Lumber mill suggested white oak with tight knots.

Thanks for sharing your thoughts.


There are many species of wood that are naturally insect and moisture resistant. Redwood comes to mind. People used this for decks long before pressure treated came along.

Just install it as you would PT wood with a sill plate gasket.

Good luck!

  • Or maybe cedar? – bib May 12 '16 at 16:55
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    Both redwood and cedar would be good choices. – Ed Beal May 12 '16 at 16:56

Go to a drywall and metal stud distributor and get some 3-5/8" 18ga track with a g90 coating. Might get a bit of surface rust over the years but it won't rot or be eaten by pest.


Solid Composite Decking (plastic)

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I've no idea of its compressive strength, but I think it'd do just fine. It is expensive though.


you could always use hemlock. it holds up well outdoors and is strong as hell


I'm not sure if ipe is a great choice for this, but I think it deserves an honorable mention because I've never seen insects eating it. The trouble with it would be needing to predrill holes (because it's so hard), and it's a bit more expensive than oak.

Regarding insect control, use borates. That's the only think that will really work out in the long run. I wouldn't trust cedar to be strong enough for a sill plate, but even if it was, I've seen bugs eating it (cedar shingles and siding). Yeah it's better than pine for resisting bugs (for a while), but bugs will attack any soft and chewy wood... and cedar will eventually lose it's protective oils. Treated lumber uses ACQ (Alkaline Copper Quaternary), but they had to abandon the use of arsenic because of tightened regualtions. Treated lumber just isn't as protected as it used to be... hence the growing popularity of alternative decking materials (like ipe and composite).

Oak is a good choice (tried and true). Ipe is as hard as oak knots.

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