I plan to build a small shed, 18ft.x18ft. and want to frame it with rough cut native lumber. It will all be covered and sitting on a concrete slab so the wood will be protected from moisture. The roof covering and sides will be metal. What I have in mind is a pole type building. I'm located in northeast Missouri so there's quite a bit of variety as far as trees goes. What suggestions do you folks have?
Thanks
Jim
what do yo have near you? white oak would be rot resistant. the concrete can wick moisture so maybe for a bottom plate. any soft woods for framing. first thoughts.
Thanks Doc
What we have for softwoods is cottonwood mainly. There won't be a bottom plate on the framing except for the nailers running horizontally for attaching the metal. I plan to use 6"x6" timbers that will sit right on top of the concrete floor and be attached with a steel bracket to the concrete. The steel siding will be 1 1/2" below the top of the floor where these post sit.
cottonwood will work. many of the hundred y/o homes here were framed with CW.
Use a standoff to get the post off the concrete or run a treated sill to sit them on that also acts as the bottom nailer. Untreated directly on concrete won't hold up.
Do you have a picture or link to a good standoff?
Tar paper or poly between the sill and concrete will prevent wicking.
Sorry, looking in the catalog but they should be at strongtie.com, I usually find stuff in the catalog and then go to the building supply and get them to order it.
ABA/ABU/ABW are the exposed steel, bolt down line of connectors with a steel standoff
CPTZ is the concealed knife plate style, CPT66Z would be for 6x6's, black poly standoff
PB/PBS are the cast in place exposed steel, PBS has the steel 1" standoff
There are a few others in there.
What Don P said. I would not be anxious to put untreated sills directly on concrete regardless of species, even several inches above grade.
I can imagine climates and locations where it is doable, but I don't live in one. A couple hundred bucks in PT lumber now, cake install now, or major headache later.
On a continuous foundation here, even 24" above grade, I would do a layer of plastic at least 6mil on the concrete, then 2x PT, then build with untreated. Check your local building codes, I am sure there is some place where they want you to put down PT, then plastic, then build.
When I think of my local snow accumulation and water table, doing what I mentioned is the difference between a building that might last 80 years and a building that will last 200 years or more.
Another vote for no untreated (or naturally super durable) wood in contact with concrete. There are various metal standoffs (galvanised) to let you attach posts to a concrete slab. Or heavy tar paper / plastic moisture barriers to protect wood laying on a sill. Or properly treated (ground contact) wood that can survive sitting on concrete for years.
Once you can protect the wood from moisture, you can build with pretty much anything. As long as you can keep it dry.
QuoteWhen I think of my local snow accumulation and water table, doing what I mentioned is the difference between a building that might last 80 years and a building that will last 200 years or more.
In our climate untreated wood on concrete wouldn't last 8 years, let alone 80 :D