Heart Side Down To the Editor: I recently read Henry Spies' response to a question on laying deck lumber in January's "On the House" column. The California Redwood Association recommends applying the pith side (heart side) down—not up. This reduces grain raising and splinters, thus providing a smoother, safer surface. Keith Kersell Manager, Technical Services The Pacific Lumber Co. San Francisco, Calif. Conflicting Opinions on Vapor Barriers To the Editor: Help! Over the past three years, you've convinced us that a good vapor barrier is essential in a well-insulated, tightly built home. We've recently visited four different manufacturers of well-built "modular" homes (with 2x6 construction, 4x10 floor joists, well-insulated walls, etc.). None of them offer vapor barriers. Some manufacturers say they used to install vapor barriers,