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.
- This procedure includes guidance on repairing cracks and checks in wood either filling, regluing or using a dutchman.
- Cracks and checks in interior wood wall ornament are usually caused by uneven shrinkage, impact damage, or improperly placed fasteners.
- See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
- Safety Precautions
- Historic Structures Precautions
- Quality Assurance
- Delivery, Storage and Handling
- Project/Site Conditions
- Sequencing and Scheduling
- 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).
- Interior wood wall ornament may include, but not be limited to, crown moulding, chair rail, wainscotting, base, door and window casings and trim, columns and posts, carved relief pieces, and built-in cabinets and bookcases.
- Wood filler: Available from hardware store; Tint to match existing woodwork.
- Paint and debris remover (paint or chemical): Available from hardware store.
- Wood glue: Available from hardware store.
- Replacement stock for dutchman: Available from builder's supply store or lumber yard.
- Sandpaper: No. 3/0 or No. 5/0 garnet paper.
- Heat gun or plate
- Table saw to cut dutchman shims
- Knife to cut excess shim
- If a check is a result of dried or shrunken end grain, it must be filled.
- Checks on the underside of wood members with no direct water infiltration generally do NOT need filling.
3.02 ERECTION, INSTALLATION, APPLICATION
- Filling cracks and checks (for small surface cracks up to 1/2" across):
- Use a proprietary wood filler, or sawdust mixed with white glue. Work into crack so that no gaps remain.
- When dry, hand rub filled area with a fine grit sandpaper to match surface characteristics and level of surrounding surfaces.
- Refinish as required to match remaining ornament.
- Regluing cracks and checks (for larger cracks that penetrate into the wood ornament):
- Strip paint and debris from crack area. Before regluing, make sure joint can be forced back together.
- Widen joint slightly to get glue in and work joint open and closed to spread glue.
- Clamp joint closed using blocks of wood under clamps to protect wood. Remove all excess glue before it dries.
- Let glue dry for 24 hours before removing clamp.
- Refinish as necessary to match surrounding ornament.
- Dutchman replacement (for larger cracks that cannot be filled or glued):
- Cut long, slender, tapered shims from wood of same age, species and grain orientation as piece being patched.
- Pre-fit shim into crack. When shim fits, glue both shim and crack surface and remove all excess glue.
- After glue dries, cut shim flush with face of panel and refinish as necessary to match remaining ornament.