Moisture Content for Outdoor Projects?

[Darrell Woolaver]

Hello all, I tried searching the forum but could not find an answer to to this specific question.

Are the rules for MC different if you are building an outdoor project?
I have several outdoor projects I would to build out of white oak. I have found a source locally at what seems a reasonable price. $1.25/bf. The guys said the logs where air dried for 1 year before being sawed into boards of about 1" thickness. This lumber has never seen a kiln.

It seems reasonable to me that if a project is going to live outdoors you should be able to work the wood even it is has only been air dried to 10% or 12%. But I really have no idea if that is true. Anybody with experience in this care to chime in?

Thanks!

[Scott T Smith]

Darrell,

Kiln Drying typically achieves three purposes:

1 - It allows the kiln operator to control of the early portion of the drying process (from green down to 35% MC) in order to reduce wood degrade.

The early portion of the kiln drying process is the most critical portion in terms of ultimate wood quality. In oak - this typically means slowing down the process during this stage.

2 - It allows control of the final moisture content for the boards (typically six to ten percent for interior wood and fourteen to eighteen percent for exterior or structural wood).

3 - It provides for sterilization of the lumber - to kill any insects such as powder posts beetles, pine borers, etc.

Wood does not dry well "in the log", and usually boards that are milled from aged logs typically have more degrade - not less. This occurs in the form of hidden stresses, etc, and the ends of the board (nearest the cut ends of the log) will be the worst. Typically if I'm milling logs that have aged for several months to a year, I will remove several inches from the ends of the log to try to reach green wood before milling and drying.

To achieve the highest possible board quality, in a theoretical world you would log (and end coat) on day 1, mill on day 2, and get into the kiln on day 3. Any increase in time between these phases will result in additional degrade.

There is nothing wrong with using air dried wood for outdoor projects, but be sure to look closely for any signs of insect infection. If you see anything, don't use the wood because the bugs are probably still inside it.

Regards,

Scott
(Kiln and sawmill operator)

[Darrell Woolaver]

Thanks Scott!!! I now know way more about lumber than I used to!
I will check out his boards closely before buying. I think it's a decent deal if they look un-infested.