Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
REPAIRING BROKEN VERTICAL TIES ON A SUSPENDED PLASTER CEILING
A. This procedure includes guidance on resecuring a sagging
suspended plaster ceiling by lifting the sag with heavy
B. Common causes of sagging plaster include the following:
1. Wood shrinkage and weight of plaster pull the
ceiling away from the joists (see 09210-04-R).
2. Lath pulling loose from the ceiling joists (see
3. Broken vertical ties (applies to this procedure).
C. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. Lag bolts
B. Heavy-gauge wire
B. Wood 2x4s for T-brace
C. Phillips head screwdriver
D. Electric drill
3.01 ERECTION, INSTALLATION, APPLICATION
A. Determine direction, location, and spacing of nailers
(they are usually perpendicular to the rafters).
B. Dig out all previously patched cracks.
C. T-brace and gently lift the sag (it may be necessary to
remove or cut back the old wood vertical ties).
D. From above the ceiling, screw lag bolts into the rafters
every 24 inches on center in both directions.
E. Using heavy-gauge wire, sling the nailers from the bolts
through the rafters; Double the wire and wrap it around
the lag bolt.
F. Bring it down, threading it between the lath and the
nailer in a void near a plaster key, and wrap it back
around the nailer; Twist it tightly around itself.