My friend's home has pine trim. Normal construction relative to wood movement was used...and these things only have a front and a top, outside of an end-cap, so expansion/contraction hasn't been an issue since the top is relatively narrow and the little bit of expansion it has seasonally doesn't materially move the front very much at all. Only the top is fastened to the house; the fronts float and the end caps are oriented the same way as the tops. They have been in place for three years now without incident. Mesh is inset from the "non-show" side in a routed and rabbited slot to allow for air movement.
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The most expensive tool is the one you buy "cheaply" and often...