Most of us have worked on old homes where the exterior trim and siding were still in great shape: no cupping, bowing, twisting, or rot. As often as not, the wood is old-growth Doug fir, and none of it — the back of the siding, the back of the brick mold, the back and bottoms of the exterior jambs — is back-primed. In many cases, not even the bottoms of the doors were painted! Try that today.

Lumber these days is hardly even "new growth" — a lot of it is more like "instant growth." Just look at the growth rings in a piece of siding or a 1x6 trim board. All this new-growth wood requires new building practices. We can no longer install doors without priming and finishing all six sides. In fact, most door...

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