>In a rib crowned system, then, how important is it to control the moisture >content in the board during installation. It sounds as if it is not so >critical. > >David Love It's not as critical structurally, since the ribs are doing the structural support work they're designed for, but you still need to assemble them within a certain MC range so the panel doesn't make the assembly overly stiff (temporarily) by excess expansion, nor crack when it dries out in the winter months. The MC range for rib crowning tends to me in the 6%- 6.5% MC range, rather than the 4% - 4.5% range for compression crowning. Ron N
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