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 severely cracked marble blocks using dutchman repair. This procedure is also appropriate for large spills in marble.
- For guidance on making other marble repairs, see 04455- 03-R, 04455-04-R, 04455-05-R, 04455-08-R, 04455-20-R and 04455-21-R.
- 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).
- American Society for Testing and Materials (ASTM) www.astm.org
- Product Data: Submit manufacturer's product data for epoxy adhesives or resins, including mixing instructions and precautionary handling instructions.
- Samples: Submit samples of marble dutchman units. Include full range of colors and textures required to match existing stone. Submit samples of stainless steel pins for patching.
1.04 QUALITY ASSURANCE
- Contractor performing the work shall have a minimum of 5 years experience in masonry restoration work of the type described for this project.
- If requested by the Owner, furnish a statement of the experience and qualifications of the firm and of the key personnel who will work on this project. Include the names and addresses of successful projects completed, and for each, the name and address of the owner and the architect.
1.05 DELIVERY, STORAGE AND HANDLING
- Packing and Shipping: Deliver stone materials to the project site in undamaged condition.
- Storeage and Protection:
- Store and handle stone to prevent their deterioration or damage due to moisture, extreme temperature changes, contaminants, breakage, chipping or other causes.
- Do not use pinch or wrecking bars to move or place stone. Lift stone with wide belt slings where possible. Use wood rollers to move stone laterally.
1.06 PROJECT/SITE CONDITIONS
- Environmental Requirements: The work is to be executed only when the air and surface temperature is 40 F and rising, or less than 90 F. No pointing or patching is to be executed when the temperature is 45 F and falling, or when freezing temperatures are expected within 48 hours.
- Jahn Restoration Mortars www.cathedralstone.com
- Sika Corporation usa.sika.com
- Marble for replacement marble pieces and dutchman repairs to match existing marble type, color and finish, complying with ASTM C503. Size of replacements and dutchman pieces shall be as required by field conditions.
- Reinforcement/Anchors: Stainless steel type 302/304 3/8" in diameter threaded rods, length as required.
- Cementitious patching material such as "M70 Stone Restoration Mortar" (Jahn Restoration), or approved equal.
- Epoxy grout: High-modulus, low viscosity, high strength epoxy grouting/sealing/binder adhesive such as "Sikadur 35, Hi-Mod LV" (Sika Corporation), or approved equal.
- Clean, soft cloths
- Clean, potable water
- Stiff fiber bristle brushes
- Stiff wire bristle brushes
- Spray bottle
- Masonry drill
- Protection: Protect existing adjacent materials during the execution of the work. Provide necessary protection and conduct work procedures to avoid damage to doors, windows, flashing, roofing and other existing material assemblies.
3.02 ERECTION, INSTALLATION, APPLICATION
- Carefully remove loose stone fragments. Reuse all pieces of spalled stone which are in sound condition without serious cracks or flaws.
- Clean any exposed metal anchors of all corrosion by scraping and brushing with a stiff wire bristle brush. Replace any unsound anchors as necessary with new stainless steel anchors of approximate size and shape to match existing. Bed new anchors in epoxy grout.
- For resecurring small fragments, see 04455-21-R for guidance.
- For larger fragments, square off the portion of spalled stone for replacement with dutchman repair. Remove dust and debris from cavity and fragments using a stiff fiber bristle brush.
- Fit the dutchman for size.
- For dutchman larger than 4" by 4" by 1", additional reinforcement may be required.
- Drill holes (size determined by size of reinforcement selected) into both the sound stone and the dutchman.
- Inject adhesive into the holes and set stainless steel pins into the holes.
- Coat abutting surfaces of the stone with epoxy adhesive, and secure the stone dutchman in place until the adhesive is cured.
- Clean any residual adhesive from the edges using a clean soft cloth. Wet the stone with clean, potable water and fill any chipped areas and edges with patching mortar. Avoid feather-edging. Tool surface level with surrounding stone. Keep mortar damp (80%-90% RH) for 72 hours or until cured.