U.S. flag

An official website of the United States government

Replacing Deteriorated Sealant

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.



A. This procedure includes guidance on removing deteriorated or inappropriate sealant and replacing with new sealant at appropriate locations.

B. 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 Precaution= s
  3. Submittals
  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. American Society for Testing and Materials (ASTM),
100 Barr Drive,
West Conshohocken, PA 19428
610-832-9585 or FAX 610-832-9555.


A. Product Data: Submit manufacturer's technical data for each type joint sealer required, including instructions for joint preparation and joint sealer application.

B. Samples: Submit manufacturer's standard bead samples consisting of strips of actual products showing full range of colors available, for each product exposed to view. Color selection by RHPO.

C. Backer Rod Sample: Submit 12" long sample of proposed backer rod. Submit certification from sealant manufacturer that backer rod is compatible with sealant.


A. Qualifications:

  1. Installer of sealant work shall have at least 5 years experience in the successful installation of sealant systems specified for this project.
  2. If requested by the Contracting Officer, installer shall submit a statement describing the firm's qualifications, experience of the personnel performing the work, and list of successful completed projects. Include the name and address of the project owner and of the RHPO.

B. Regulatory Requirements: Work of this section shall comply with applicable standards indicated.

C. Certifications: Submit written certification from sealant manufacturer or manufacturer's representative that, after visiting the site and examining the conditions and locations where sealant will be installed, the sealant specified is correct for the use intended. If sealant is not correct for the situation, the manufacturer shall submit in writing to the RHPO the recommendation for the correct sealant to be used.

D. Field Samples:

  1. Provide products of listed or other approved manufacturers. Provide products from single source or manufacturer for each product during course of the work.

E. Mock-Ups:

  1. Contracting Officer will select a location for installer to install a 3 foot section of each sealant system specified.=
  2. After curing and prior to approval of test panel, installer shall test adhesion of joint my manually trying to pull sealant from joint. Test shall be performed in the presence of the Contracting Officer and representative of sealant manufacturer.
  3. Approved test panels shall become an integral part of the work and serve as standard for similar work on this project.


A. Packing and Shipping: Deliver materials to the site in original unopened containers or bundles with labels informing about manufacturer, product name, color, expiration date for use, pot life, curing time and mixing instructions for multi-component products.

B. Store and handle materials to prevent their deterioration or damage by temperature changes, contaminants or other causes. Remove damaged material from the site to prevent use and replace with new material.


A. Existing Conditions: Do not proceed with sealant work during inclement weather or forecast of inclement weather, or when temperature is above or below manufacturer's recommended limitations for installation.



A. Pecora Corporation
165 Wambold Road
Harleysville, PA 19438
800/522-1285 or 215/723-6051
2601 Oakland Avenue
Garland, TX 75041
800/523-6688 or 214/278-8158

B. Sika Corporation
201 Polito Ave.
Lyndhurst, NJ 07071

C. Sonneborn Building Products

D. Tremco, Inc.
3735 Green Rd.
Beachwood, OH 44122

E. Williams Products, Inc.

F. Bostik, Inc.
Bostik Construction
Products 211 Boston St.
Middleton, MA 01949


A. Exterior sealant to be a non-sag, gun grade, sealant complying with ASTM C920, such as those manufactured by (Pecora Corp.), (Sika Corp.), (Sonneborn Building Products), (Tremco, Inc.), or approved equal. Color shall be selected by RHPO from manufacturer's full range of colors. See also 07900-01-S for guidance in selecting an appropriate sealant.

B. Traffic-type sealant for horizontal joints to be non- staining, non-sag, sealant complying with ASTM C920, such as those manufactured by (Pecora Corp.), (Sika Corp.), (Tremco, Inc.), or approved equal.

C. Backer rod to be a closed-cell polyethylene or polyurethane rod of diameter recommended by manufacturer for opening width; such as "Green Rod" (NMC, Inc.), "Chem-Rod/Closed" (Bostik Construction Products Division, Emhart), "Sonofoam Closed Cell Backer Rod" (Sonneborn Building Products), "Expand-O-Foam" (Williams Products, Inc.), or approved equal. Verify compatibility of backer rod and sealant before installation.

D. Joint primer and cleaner shall be as recommended by sealant manufacturer for joint surfaces. Contractor shall verify with manufacturer need for primer and correct product for type of material on which sealant will be applied. Manufacturer's literature shall not be used as basis for primer requirement.

E. Joint filler for traffic sealant joints shall be a reconstituted, closed cell sponge neoprene, having a density of 30 lbs. per cubic foot and conforming to ASTM D1752, Type I.

F. Bond breaker tape shall be an adhesive backed polyethylene tape compatible with sealant. Verify with sealant manufacturer prior to use.

G. Masking tape for protection of materials adjacent to joint to be a non-staining, non-absorbent type compatible with sealant and surfaces.



A. Verification of Conditions: Inspect joints to receive sealant prior to commencing work for compliance with joint requirements, tolerances and other conditions affecting sealant performance. Do not proceed with sealant installation until corrections or adjustments have been made.


A. Clean out joints to receive sealant of dirt, grease, or other foreign materials.

B. Vacuum or brush joints using non-ferrous brush and blow dry.

C. Install backer rod where joints are deeper than AB" or bond breaker tape if less than AB", into joint to provide sealant depth recommended by sealant manufacturer. Backer rod size shall be selected to allow for a minimum of 30% compression of the backing when inserted into the joint.

D. Tape shoulders of joint during installation and tooling of sealant to aid in the removal of excess sealant and to prevent staining of masonry. Remove tape after tooling of joint.

E. Fill joint completely with sealant in accordance with manufacturer's instructions.

F. Tool immediately after application to ensure firm, full contact with the inner faces of the joint. Finished bead shall be smooth, continuous, and slightly concave.

G. Clean excess sealant off adjacent surfaces immediately after tooling and removal of tape. Do not use any cleaners or agents that will stain the sealant or adjacent surfaces.


A. Installer shall instruct the Contractor in the methods to be used to cure and protect the sealant from damage during construction period, other than normal wear and weathering.

B. Replace damaged or deteriorated sealants prior to completion of the project, and during warranty period of product by manufacturer.