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Paris Santa l%-Frisco Depot Rehabilitation © KEYSTONE ARCHITECTS <br /> July 10, 2001 <br /> <br /> 5. Small Holes (less than 4" diameter): Where damage involves loss of <br /> brown and finish coats, make repair in two applications. First trowel on a <br /> basecoat layer and scrape back below level of existing plaster. After <br /> basecoat has set, but not dried, apply another coat of plaster to create a <br /> level, smooth surface. <br /> <br /> 6. Large Holes and Areas: Remove all loose, crumbling, powdery, or rotted <br /> plaster down to the wood lath. Feather edges of firmly attached plaster to <br /> expose all three layers of plaster. Clean lath and re-nail and repair as <br /> necessary to restore structural integrity. Spray lath with fine mist of water <br /> or use bonding agent. Attach expanded metal lath to wood lath with tie <br /> wires. Apply three coat plaster system, lapping each new layer over each <br /> old plaster layer so that old and new are evenly joined and produce a <br /> strong, invisible patch. The contours of the new patch shall conform to <br /> the contours of the adjacent existing plaster surfaces. <br /> <br /> 7. Ceiling, Small to Medium Holes, Structurally Sound Lath: Proceed as <br /> with method No. 6 above. If in doubt as to reparability and structural <br /> integrity of existing lath, proceed as with method No. 8 below. <br /> <br /> 8. Ceiling, Small to Large Holes or Areas, Structurally Unsound Lath: <br /> Remove all loose, crumbling, powdery, or rotted plaster as well as rotted <br /> wood lath. Remaining areas of firmly attached plaster and structurally <br /> sound lath must span without bowing, sagging or deflecting to adjacent <br /> ceiling joists. Areas which do not meet this criteria shall be removed. In <br /> such areas, install: <br /> <br /> a. A new plaster system consisting of 1/2" structural plywood <br /> attached to ceiling joists with 2" wood screws. Attach metal lath <br /> securely to plywood with staple cleats. Apply three coat plaster <br /> system, lapping each new layer over each old plaster layer so that <br /> old and new are evenly joined and produce a strong, invisible <br /> patch. <br /> <br /> b. A new drywall system consisting of 5/8" gypsum plaster attached <br /> to ceiling joists with drywall screws, taped, floated, and textured to <br /> match historic plaster. <br /> Section 09910 <br /> Page 6-7 <br /> <br /> <br />