Sealing Masonry Joints To Make Them Airtight And Watertight

Procedure code:
Fed Bldg/Uspo/Spokane, Wa - Gsa/Pbs, 3-11-91
Thermal and Moisture Protection
Joint Sealers
Last Modified:




A. This procedure includes guidance on installing joint sealers at masonry joints for the following locations:

  1. Exterior joints in vertical surfaces and non- traffic horizontal surfaces; these may include perimeter joints at frames of doors and windows.
  2. Exterior joints in horizontal traffic surfaces; these may include joints in stone steps (see also 04465-07-R).
  3. Interior joints in vertical surfaces and horizontal non-traffic surfaces; these may include perimeter joints between interior wall surfaces and frames of interior doors, windows and elevator entrances, or perimeter joints of toilet fixtures
  4. Interior joints in horizontal traffic surfaces; these may include joints in stone steps.

B. For guidance on selecting joint sealants for masonry, based on composition, elasticity and durability, see 07900-01-S "Criteria For Selecting Masonry Joint Sealants.


A. American Society for Testing and Materials (ASTM),
100 Barr Drive,
West Conshohocken,
PA 19428,
610-832-9585 or FAX 610-832-9555.


A. Provide joint sealers that have been produced and installed to establish and maintain watertight and airtight continuous seals.


A. Product Data from manufacturer's for each joint sealer product required, including instructions for joint preparation and joint sealer application

B. Samples of each type and color of joint sealer required. Install joint sealer samples in 1/2" wide joints formed between two 6" long strips of material matching the appearance of exposed surfaces adjacent to joint sealers.

C. Certificates from manufacturers of joint sealers attesting that their products comply with specification requirements and are suitable for the use indicated.


A. Installer Qualifications: Engage an Installer who has successfully completed within the last 3 years at least 3 joint sealer applications similar in type and size to that of this project.

B. Single Source Responsibility for Joint Sealer Materials: Obtain joint sealer materials from a single manufacturer for each different product required.

C. Preconstruction Field Testing: Prior to installation of joint sealants, field-test their adhesion to joint substrates as follows:

  1. Conduct field tests for each application indicated below:
    • Each type of elastomeric sealant and joint substrate indicated.
    • Each type of non-elastomeric sealant and joint substrate indicated.
  2. Arrange for tests to take place with both RHPO and joint sealer manufacturer's technical representative present.
  3. Test Method: Test joint sealers by hand pull method described below:
    • Install joint sealants in 5-feet joint lengths using same materials and methods required for joint preparation and joint sealant installation required for completed work. Allow sealants to cure fully before testing
    • Make knife cuts as follows: A horizontal cut from one side of joint to the other followed by 2 vertical cuts approximately 2" long at side of joint and meeting horizontal cut at top of 2" cuts. Place a mark 1" from top of 2" piece.
    • Use fingers to grasp 2" piece of sealant just above 1" mark; pull firmly down at a 90 degree angle or more while holding a ruler along side of sealant. Pull sealant out of joint to the distance recommended by sealant manufacturer for testing adhesive compatibility, but not less than that equaling specified maximum movement capability in extension; hold this position for 10 seconds.
  4. Report whether or not sealant in joint connected to pulled-out portion failed to adhere to joint substrates or tore cohesively. Include data on pull distance used to test each type of product and joint substrate.
  5. Evaluation of Field Test Results: Sealants not evidencing adhesive failure from testing, in absence of other indications of noncompliance with requirements, will be considered satisfactory. Do not use sealants which fail to adhere to joint substrates during testing.

D. Pre-Installation Meeting: At contractor's direction, installer, joint sealer manufacturers' representatives, and other trades whose work affects installation of joint sealers shall meet at project site to review procedures and time schedule proposed for installation of joint sealers which is coordinated with other, related work.


A. Acceptance at Site: Deliver materials to project site in original unopened containers or bundles with labels informing about manufacturer, product name and designation, color, expiration period for use, pot life, curing time and mixing instructions for multi-component materials.

B. Storage and Protection: Store and handle materials in compliance with manufacturer's recommendations to prevent their deterioration or damage due to moisture, high or low temperatures, contaminants, or other causes.


A. Environmental Conditions: Do not proceed with installation of joint sealers under the following conditions:

  1. When ambient and substrate temperature conditions are outside the limits permitted by joint sealer manufacturer or below 40 degrees F (4.4 degrees C).
  2. When joint substrates are wet due to rain, frost, condensation or other causes.

B. Joint Width Conditions: Do not proceed with installation of joint sealers where joint widths are less than allowed by joint sealer manufacturer for application indicated

C. Joint Substrate Conditions: Do not proceed with installation of joint sealers until contaminants capable of interfering with their adhesion are removed for joint substrates.


A. Sequence installation of joint sealers to occur not less than 21 nor more than 30 days after completion of waterproofing, unless otherwise indicated.



A. Bostik Construction Products
Boston Street Middleton,
MA 01949
800/726-7845, FAX 508/774-7376

B. Dow Corning Corporation
1225 Northmeadow Parkway,
Ste. 104
Roswell, GA 30076


P.O. Box 994
Midland, MI 48686-0994

C. General Electric Co.
Silicone Products Division
Waterford, NY 12188

D. Mameco International, Inc.
4475 East 175th Street
Cleveland, OH 44128

E. 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

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

G. 3M Consumer Products Group
Box 33053
St. Paul, MN 55133-3053
612/737-6501 or 800/364-3577

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


A. For additional guidance on selecting masonry joint sealants, see 07900-01-S "Criteria for Selecting Masonry Joint Sealants".

B. General:

  1. Compatibility: Provide joint sealers, joint fillers and other related materials that are compatible with one another and with joint substrates under conditions of service and application, as demonstrated by sealant manufacturer based on testing and field experience.
  2. Colors: Provide color of exposed joint sealer indicated or, if not otherwise indicated, as selected by Contracting Officer from manufacturer's standard colors.

C. Elastomeric Joint Sealants:

  1. Elastomeric Sealant Standard: Provide manufacturer's standard chemically curing, elastomeric sealant of base polymer indicated which complies with ASTM C920 requirements, including those referenced for Type, Grade, Class and Uses.
  2. One-Part Mildew-Resistant Silicone Sealant such as "Dow Corning 786" (Dow Corning Corporation), "SCS 1702" (General Electric Co.), or approved equal. a. Type S; Grade NS; Class 25 b. Uses NT, G, A, and, as applicable to non-porous joint substrate indicated, O c. Formulated with fungicide for sealing interior joints with nonporous substrate around ceramic tile, showers, sinks and plumbing fixtures.
    • One-Part Non-sag Urethane Sealant for Use NT such as "Chem-Calk 900" or "Chem-Calk 2639" (Bostik Construction Products), "Vulkem 116" or "Vulkem 921" (Mameco International, Inc.), "Sikaflex-1a" or "Sikaflex-15LM" (Sika Corporation), or approved equal. a. Type S; Grade NS; Class 25 b. Uses NT, M, A, and, as applicable to joint substrates indicated, O.
  3. One-Part Non-sag Urethane Sealant for Use T such as "Chem-Calk 900" (Bostik Construction Products), "Sikaflex-1a" or "Sikaflex-15LM" (Sika Corporation), or approved equal. a. Type S; Grade P; Class 25. b. Uses T, M, and, as applicable to joint substrates indicated, O.
  4. One-Part Pourable Urethane Sealant for Use T such as "Chem-Calk 950" (Bostik Construction Products) "Vulkem 45" (Mameco International, Inc.), or approved equal.

D. Latex Joint Sealants:

  1. Acrylic-Emulsion Sealant such as "Chem-Calk 600" (Bostik Construction Products), or approved equal.
    • Manufacturer's standard, one part, non-sag, acrylic, mildew-resistant, acrylic-emulsion sealant complying with ASTM C834.
    • b. Formulated to be painted and recommended for exposed applications on interior and on protected exterior exposures involving joint movement of not more than + or - 7.5%.

E. Acoustical Joint Sealants:

  1. Acoustical Sealant for Concealed Joints such as "BA098" (Pecora Corporation), "Tremco Acoustical Sealant" (Tremco, Inc.), or approved equal.
    • Manufacturer's standard, non-drying, non-hardening, non-skinning, non-staining, gunnable, synthetic rubber sealant.
    • Recommended for sealing interior concealed joints to reduce transmission of airborne sound.

F. Fire-Resistant Joint Sealers:

  1. General: Provide manufacturer's standard fire- stopping sealant, with accessory materials, having fire-resistance ratings indicated as established by testing identical assemblies per ASTM E814 by Underwriters Laboratory, Inc. or other testing and inspecting agency acceptable to authorities having jurisdiction.
  2. Foamed-In-Place Fire-Stopping Sealant such as "Dow Corning Fire Stop Foam" (Dow Corning Corporation), "Pensil 851" (General Electric Co.), or approved equal.
    • Two-part, foamed-in-place, silicone sealant formulated for use in a through-penetration fire-stop system.
    • For filling openings around cables, conduit, pipes and similar penetrations through walls and floors.
  3. One-Part Fire-Stopping Sealant such as "Dow Corning Fire Stop Sealant" (Dow Corning Corporation), "3M Fire Barrier Caulk CP-25" (Electrical Products Div./3M), "RTV 7403" (General Electric Co.), or approved equal.
    • One-part elastomeric sealant formulated for use in a through-penetration fire-stop system.
    • For sealing openings around cables, conduit, pipes and similar penetrations through walls and floors.

G. Joint Sealant Backing:

  1. General: Provide sealant backings of material and type which are non-staining; are compatible with joint substrates, sealants, primers and other joint fillers; and are approved for applications indicated by sealant manufacturer based on field experience and laboratory testing.
  2. Plastic Foam Joint Fillers: Preformed, compressible, resilient, non-waxing, non-extruding strips of flexible, non-gassing plastic foam of material indicated below; non-absorbent to water and gas; and of size, shape and density to control sealant depth and otherwise contribute to producing optimum sealant performance.
    • Either open cell polyurethane foam or closed- cell polyethylene foam, unless otherwise indicated, subject to approval of sealant manufacturer, for cold-applied sealants only.
    • Elastomeric Tubing Joint-Fillers: Neoprene, butyl or EPDM tubing complying with ASTM D1056, non-absorbent to water and gas, capable of remaining resilient at temperatures down to -26 degrees F (-15 degrees C). Provide products with low compression set and of size and shape to provide a secondary seal, to control sealant depth and otherwise contribute to optimum sealant performance.
  3. Bond-Breaker Tape: Polyethylene tape or other plastic tape as recommended by sealant manufacturer for preventing sealant from adhering to rigid, inflexible joint filler materials or joint surfaces at back of joint where such adhesion would result in sealant failure. Provide self-adhesive tape where applicable.

H. Miscellaneous Materials:

  1. Primer: Provide type recommended by joint sealer manufacturer where required for adhesion of sealant to joint substrates indicated, as determined from preconstruction joint sealer substrate tests and field tests.
  2. Cleaners for Nonporous Surfaces: Provide non- staining, chemical cleaners of type which are acceptable to manufacturer of sealants and sealant backing materials, which are not harmful to substrates and adjacent non-porous materials, and which do not leave oily residues or otherwise have a detrimental effect on sealant adhesion or in- service performance.
  3. Masking Tape: Provide non-staining, non-absorbent type compatible with joint sealants and to surfaces adjacent to joints.
  4. Accessory materials for Fire-Stopping Sealants: Provide forming, joint-fillers, packing and other accessory materials required for installation of fire-stopping sealants as applicable to installation conditions indicated.

I. Joint Fillers for Concrete Paving:

  1. General: Provide joint fillers of thickness and widths indicated.
  2. Bituminous Fiber Joint Filler: Preformed strips of composition below, complying with ASTM D1751:
    • Asphalt saturated fiberboard.



A. Examine joints indicated to receive joint sealers, with installer present, for compliance with requirements for joint configuration, installation tolerances and other conditions affecting joint sealer performance. Do not proceed with installation of joint sealers until unsatisfactory conditions have been corrected.


A. Surface Preparation:

  1. Joint and Surface Cleaning:
    • Clean out joints immediately before installing joint sealers to comply with recommendations of joint sealer manufacturers and the following requirements:
    • Remove all foreign material from joint substrates which could interfere with adhesion of joint sealer, including dust; paints, except for permanent, protective coatings tested and approved for sealant adhesion and compatibility by sealant manufacturer; old joint sealers; oil; grease; waterproofing; water repellents; water; surface dirt and frost.
    • Clean concrete, masonry, unglazed surfaces of ceramic tile and similar porous joint substrate surfaces, by brushing, grinding, blast cleaning, mechanical abrading, or a combination of these methods to produce a clean, sound substrate capable of developing optimum bond with joint sealers. Remove loose particles remaining from above cleaning operations by vacuuming or blowing out joints with oil-free compressed air.
    • Remove laitance and form release agents from concrete.
    • e. Clean metal, glass, porcelain enamel, glazed surfaces of ceramic tile and other non-porous surfaces by chemical cleaners or other means which are not harmful to substrates or leave residues capable of interfering with adhesion of joint sealers.
  2. Joint Priming: Prime joint substrates where indicated or where recommended by joint sealer manufacturer based on preconstruction joint sealer- substrate tests or prior experience. Apply primer to comply with joint sealer of manufacturer's recommendations. Confine primers to areas of joint sealer bond, do not allow spillage or migration onto adjoining surfaces.
  3. Masking Tape: Use masking tape where required to prevent contact of sealant with adjoining surfaces which otherwise would be permanently stained or damaged by such contact or by cleaning methods required to remove sealant smears. Remove tape immediately after tooling without disturbing joint seal.


A. General: Comply with joint sealer manufacturers' printed installation instructions applicable to products and applications indicated, except where more stringent requirements apply.

B. Elastomeric Sealant Installation Standard: Comply with recommendations of ASTM C962 for use of joint sealants as applicable to materials, applications and conditions indicated.

C. Latex Sealant Installation Standard: Comply with requirements of ASTM C790 for use of latex sealants.

D. Installation of Sealant Backings: Install sealant backings to comply with the following requirements:

  1. Install joint-fillers of type indicated to provide support of sealants during application and at position required to produce the cross-sectional shapes and depths of installed sealants relative to joint widths which allow optimum sealant movement capability.
    • Do not leave gaps between ends of joint-fillers.
    • Do not stretch, twist, puncture or tear joint fillers.
    • Remove absorbent joint fillers which have become wet prior to sealant application and replace with dry material.
  2. Install bond breaker tape between sealants and joint-fillers, compression seals or back of joints where adhesion of sealant to surfaces at back of joints would result in sealant failure.

E. Installation of Sealants: Install sealants by proven techniques that result in sealants directly contacting and fully wetting joint substrates, completely filling recesses provided for each joint configuration and providing uniform, cross-sectional shapes and depths relative to joint widths which allow optimum sealant movement capability.

F. Tooling of Non-sag Sealants: Immediately after sealant application and prior to time skinning or curing begins, tool sealants to form smooth, uniform beads of configuration indicated, to eliminate air pockets and to ensure contact and adhesion of sealant with sides of joint. Remove excess sealants from surfaces adjacent to joint. Do not use tooling agents which discolor sealants or adjacent surfaces or are not approved by sealant manufacturer.

  1. Provide concave joint configuration per Figure 6A in ASTM C962, unless otherwise indicated.
    • Use masking tape to protect adjacent surfaces of recessed tooled joints.

G. Pourable sealants shall be applied by gun or by pouring, filling the joint completely with a slight recessed finish. Additional material will be added if low spots develop.

H. Installation of Fire-Stopping Sealant: Install sealant, including forming, packing and other accessory materials to fill openings around mechanical and electrical services penetrating floors and walls to provide fire- stops with fire resistance ratings indicated for floor or wall assembly in which penetration occurs. Comply with installation requirements established by testing and inspecting agency.


A. Clean off excess sealants or sealant smears adjacent to joints as work progresses by methods and with cleaning materials approved by manufacturers of joint sealers and of products in which joints occur.


A. Protect joint sealers during and after curing period from contact with contaminating substances or from damage resulting from construction operations or other causes so that they are without deterioration or damage at time of substantial completion. If, despite such protection, damage or deterioration occurs, cut out and remove damaged or deteriorated joint sealers immediately and reseal joints with new materials to produce joint sealer installations with repaired areas indistinguishable from original work.

Last Reviewed: 2017-08-13