V2 For drywalled construction that might get flooded

[rcjordan]

V1: For drywalled construction that might get flooded, lay the bottom course of drywall with the top edge at chair rail height. If you're using bat insulation make a joint in it at the top of the lower drywall sheet. Finish installing the insulation with 2nd piece on top of the bottom one.

Install the chair rail mostly on the bottom drywall with the top edge of it slightly covering the drywall joint. If/when it floods but is at or below the chair rail all you have to demolish and haul out is from the chair rail down.

V2:  This version is if you have had to deal with this multiple times.

Cut off the beveled edges on the first 2 courses of drywall so that you don't have to use joint compound & tape and can leave the joint unfinished.  Install the chair rail only on the TOP drywall with about 3/8" overhanging the bottom sheet. Put a paper-thin shim under the chair rail so that it is not snug on the face of the bottom drywall. Install the bottom drywall but raise it 1/2" off the finished floor level -this will be covered by baseboard.

When demo-ing, don't remove the chair railing, just slip the bottom sheet out from under it.