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Moisture content of exterior trim cedar

kevinjm4 | Posted in General Questions on

Where I am, most of the material I’m finding is green, at least the 2x I need in order to mill my own exterior window sills.

I live in 4c.

Since I couldn’t find 2xKD cedar at the time I bought green… but I think next time I’ll spend the little bit extra time looking for the KD.

Three questions:

What is an appropriate MC for western red cedar before applying the primer?

Is there any difference in ripping/milling a dry vs a green board? What I’m getting at is I will be turning these 2x into sills, and caps – should the milling wait until their MC is appropriate? It seems to me if milled when green it’ll only speed up drying process. But maybe it’s not a good idea for other reasons.

What needs to or should be done, if anything, to help sufficiently dry out… 1) green boards 2) oil primed boards, and 3) primed+acrylic painted boards. Ihave all three of those types of boards lying around, so I’ll need some help, tips, etc.

thanks again!

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  1. GBA Editor
    Martin Holladay | | #1

    You want to air-dry your green lumber before you attempt to plane it or mill it, for many reasons. One reason is that lumber can twist or cup as it dries, and milling or planing takes care of these problems.

    For more information on air-drying lumber, see these resources:

    "Air Drying of Lumber"

    "Drying Wood at Home"

    "How to Succeed at Air-Drying Lumber"

    Green lumber should be stickered, under cover, until it reaches its equilibrium moisture content. This equilibrium moisture content depends on the local climate, but will probably be in the range of 10% to 16% moisture content.

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