First of all, I would pull the old skins if they are in good shape, and store them for resale, or reuse on another project. Secondly, fit up the new skins, tack them in place, lay out all, or mark the location of new screws to where there is known blocking. Pre-drill screw holes with an 8"-to 12" schedule in the field. Screw perimeter screws 4" on center. Seal the entire sheet, or framing member with elastomeric seam sealer. Depending on how fast you work, the work should not take more than 40 hrs.
David Elledge
April 2010
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