Construction Joint Sealants: A Critical Part of Building Envelope Performance
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Construction Joint Sealants: A Critical Part of Building Envelope Performance
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Construction Joint Sealants: A Critical Part of Building Envelope Performance
- 2. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approved or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. W. R. MEADOWS is a Registered Provider with the American Institute of Architects (AIA) Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request.
- 3. • Terminology • Sealant Purpose • Sealant Applications • Common Problems Learning objectives- Topics of Discussion • Joint Design • Critical Success Factors • Material Selection
- 4. • Sealants were first used in pre-history (mud, grass and reeds) • Natural sealants and adhesive-sealants included plant resins such as pine pitch and birch pitch, bitumen, wax, tar, natural gum, clay (mud) mortar, lime mortar, lead, blood and egg • In the 17th century glazing putty/oil based putties (caulk) was first used to seal window glass (linseed oil/chalk) • 1920s polymers such as acrylic, butyl , and silicone polymers were first developed and used in sealants • By the 1960s synthetic-polymer-based sealants were widely utilized. • 1950’s – Polysulfide • 1960’s – Polyurethane • 1970’s – Silicone • 1990’s – Silyl Terminated Polyether (MS Polymer) Joint Sealants - Introduction/History
- 5. What’s the difference between a caulk and a sealant? A caulk is any low or intermediate performance compound. Typically being lower quality and having limited service lives. For example: Acrylic Latex, Butyl, Butyl Rubber, Co-polymers, putty, etc. Life cycle: Usually 3-5 years. A sealant typically refers to a high performance compound having more expensive ingredients, little shrinkage, excellent weathering and UV resistance, and providing long service life cycles from 10-20 years. Terminology – The Basics
- 6. • Low Modulus Sealant – Creates low stress at the sealant bond line. Usually has a higher movement capability. • Medium Modulus Sealant – Typically a general purpose sealant that can be used for the majority of elastomeric sealant applications. • High Modulus Sealant – Not used for moving joints, typically used for glazing applications. Terminology – The Basics
- 7. The Purpose • Seal penetrations/joints between construction elements… Should be considered a critical part of the building envelope • Some moving joints, some non-moving • Prevent ingress of water/moisture to building interior or through joints/gaps • Water damage • Concrete corrosion • Structural steel damage • Help prevent mold development • Prevent hard material or snow/ice from entering openings or joints… structural damage Joint Sealants
- 8. The Purpose • Accommodate Movement • Function as part of an Air Barrier System • Function as part of a Vapor Retarding System • Acoustic Control Joint Sealants
- 9. Typical applications • High-rise and low-rise commercial buildings • Window perimeters • Roofing terminations • Expansion joints and butt terminations • Glazing • Plaza decks • Tilt-Wall Exteriors • Institutional • Prisons and Schools • Airport pavement runways and aprons Joint Sealants
- 10. Typical applications • Bridge and Highway joints (DOT) • Commercial parking lots and flat work • Public Works • Sidewalks (concrete) • Park Decks • Can be in combination with deck system • Waste & Water • Submerged environments (NSF) • Adhesive and bonding applications • Industrial, Residential, and Commercial Joint Sealants
- 11. • Concrete • Masonry & Brick • Wood, Plywood, and Cement-Based Siding • EIFS (Exterior Insulation and Finish Systems) • Stucco • Stone, Manufactured Stone, Cultured Stone • Vinyl and Aluminum Siding • Painted Products • Foam Plastic Panels • Ceramic Tile • Metal Panels (Coated and Uncoated) • Systems include Door, Windows, Skylights Typical Sealed Building Products & Materials
- 12. ASTM C 920 The standard specification for elastomeric joint sealants. It is made up of several ASTM test methods including: • Movement capability (ASTM C 719) • Sealant hardness (ASTM C 661) • Tack free time (ASTM C 679) • Adhesion in peel (ASTM C 794) Joint Sealants - Terminology
- 13. ASTM C 920 • Type S = Single Component • Type M = Multi-Component • Grade P= Pourable • NS = Non-Sag • Class 25 = 25% movement Joint Sealants - Terminology
- 14. Movement Capability – ASTM C 719 Measures the cyclic moment (extension [+] and compression [-] of a sealant.) Classified with the following movement classes: • +/- 12.5 % • +/- 25 % • +/- 35 % • +/- 50 % • +/- 100/50 % Joint Sealants - Terminology
- 15. Joint Sealants – Expansion Joints
- 16. Joint Sealants – EIFS
- 17. Joint Sealants – Window & Door Perimeters
- 18. Joint Sealants – Masonry Construction
- 19. Joint Sealants – High Rise Buildings
- 20. Joint Sealants – Vertical/Horizontal Joints in Concrete
- 21. Joint Sealants – Plaza Decks and Sidewalks
- 22. Like most waterproofing aspects, joint sealants are susceptible to Value Engineering. Science and art are both needed to complete proper joints, including design and sealant placement. • Need to have: • Proper joint design • Proper product • Proper application Joint Sealants – Common Problems • Adhesion Failure – Debond from the joint sidewall • Poor surface preparation • Not correct sealant for application • Improper priming
- 23. Note: Severe weathering and UV degradation resulting in chalking and surface crazing of the sealant. Joint Sealants – Typical Adhesion Loss
- 24. Causes • Poor surface preparation • Contamination • Improper installation • Improper priming Remedies • Grinding • Proper cleaning • Proper priming • Proper tooling Joint Sealants – Adhesion Failure Causes
- 25. Cohesion Failure – Failure of the joint sealant to maintain integrity, tearing or ripping down its mid line: • Excessive movement beyond the sealant’s ability • Three sided adhesion • Inadequate thickness of sealant to function in the joint Joint Sealants – Common Problems
- 26. Causes • Poor joint design • Improper W/D ratio • Wrong sealant Remedies • Proper joint design • Choose the right sealant • Install correctly Joint Sealants – Causes: Cohesive Failure
- 27. Joint Sealants – Substrate Failure
- 28. Joint Design • Standard Recommended Practice: • Joint depth no smaller than ¼” and no greater than ½” • Use 2:1 width to depth ratio up to 1” in width. Consider an “hourglass” shape. • Joint designed within sealants movement capability • Movement related: Allow for both conditions • A joint sealed at the lowest temperature will ALWAYS experience compression • A joint sealed at the highest temperature will ALWAYS experience extension Joint Sealants – Critical Design Success Factors
- 29. • Joint design • Material selection Joint Sealants – Design Factors for Success
- 30. • Joint design • Material selection Joint Sealants – Application Success Factors
- 31. Joint Design • Joint depth should be sufficient to accept backing materials and proper depth of sealant. • Backing material should be large enough to prevent floating or sinking. • The number and spacing of joints is absolutely critical to performance • Joints should be accessible for sealant placement • There should be sufficient bonding surface for sealant • Window perimeters • Exposed aggregate facades Joint Sealants – Success Factors
- 33. Material Selection • Will the selected material handle the anticipated joint movement requirements • Adhesion to substrate is probably the most critical element in the selection process • Does the joint size allow for sufficient placement of selected materials • Will the product perform under the stated conditions of use • Is there history of application success • Evaluate the supplier’s resources • Third party testing should confirm product performance Joint Sealants – Critical Success Factors
- 34. Most Common • Latex • Acrylic • Butyls • Polysulfides • STP/MS Hybrids • Polyurethanes • Silicones Joint Sealants – Sealant Types
- 35. • Some refer to as caulk, not sealant • Interior applications • +/- 10% movement capability or less • Paintable with latex paints • Interior applications only • Dry wall to trim work • Not for “true” joints (those expected to exhibit significant cyclic movement) Sealant Types – Latex
- 36. • Some refer to as caulk, not sealant • Generally +/- 7.5% movement • More flexible than latex caulks but still not high performance by industry standards • Can be painted Sealant Types – Acrylics
- 37. • Bonds excellent to most substrates • Poor movement, generally +/- 10% or less • Poor weathering • Good as adhesive in industrial and packaging applications • Sometime used in curtain wall where adhesion to rubber compounds is needed • Most are stringy and difficult to neatly apply Sealant Types – Butyls
- 38. • The first “high performance” sealant chemistry, do not perform as well as newer polyurethanes and silicones in moving joints • Poor recovery • Can be formulated for excellent chemical resistance • Good in submerged applications • Require primer on almost all substrates Sealant Types – Polysulfides
- 39. • Silane Terminated Polyether or Polyurethane • No glazing (avoid direct contact to glass) • Excellent bonding, generally without a primer to non-porous substrates • Good UV resistance • Excellent weathering Sealant Types – STP/MS Hybrids
- 40. • Most common sealant for a wide variety of substrates • No glazing (avoid direct contact to glass) • Excellent bonding, generally without a primer, especially to cement based substrates like concrete and masonry • More forgiving in less than perfect application conditions • Good UV resistance • Excellent weathering Sealant Types – Polyurethanes
- 41. Sealants – Use by Type Use Latex Acrylic Butyl Polysulfide Silicone Polyurethane Submerged 1 1 3 4 1 4 Interior 4 4 3 3 4 4 Exterior 1 2 1 3 4 4 Struct. Glazing 1 1 1 1 4 1 Window perimeter 1 2 1 3 4 4 Expansion joints 1 1 1 2 4 4 Traffic joints 1 1 1 3 2 4 Wide joints 1 1 1 1 3 3 Paintable 4 3 2 1 1 4 Chem. Resist 1 1 1 4 1 3 EIFS 1 1 1 1 4 4 Tilt-up 1 1 1 2 2 4 Pre-cast 1 1 1 2 4 4 Cast-in-place 1 1 1 2 3 4 Brickwork 1 1 1 2 2 4 Curtain wall 1 1 2 2 4 2 UV resistance 1 3 2 3 4 3 1 = NR 2 = poor 3 = good 4 = excellent
- 42. Material Selection Joint Sealants – Critical Success Factors Polyurethanes Silicones Superior primerless adhesion to porous substrates and very forgiving to less than pristine application conditions Superior adhesion to glass, especially in applications subject to reflected UV at bond line. Non-stainging: No fluid migration from sealant to poroud substrates. Material does not chalk or discolo over long term exposure to UV. Resistant to dirt pick-up during and post installation. Use in submerged applications. Paintable with most water based elastomeric coatings. Key Material Features Non-yellowing.
- 43. Substrate Preparation • If done properly, would probably eliminate 95% of all call backs • Most common mode of sealant failure • Must remove all weak material on bonding surface of porous substrates • Surfaces must be clean, dry, free of dew or frost • Use best practices as recommended by industry experts • Porous: Abrasive, high pretty water (allow surface to dry), grinding, wire brush, compressed air (oil free) • Non-porous: 2 rag method (clean, lint-free, and absorbent – solvent wipe followed by an immediate dry cloth wipe. Do not spread contaminants) Sealant Installation – Critical Success Factors
- 44. • Wire brushing • Sand blasting • Grinding • Sawing Sealant Installation – Mechanical Method
- 45. Saw cut joint – to provide proper width and sound joint interface. Sealant Installation – Mechanical Method
- 46. Priming Priming can help get a better bond in many situations. • Priming does not substitute for good prep • Many products perform w/out primers • Most commonly used on horizontal and submerged applications • Must be done properly to work (primers are not error free: ponding, waiting time, etc.) Sealant Installation – Critical Success Factors Proper primer application with brush: • Prime only one side of joint • Primer outside of the joint may stain the substrate • Prime & seal the same day
- 47. Backing Materials Why use backer rod: • Attain proper wetting of substrate when sealant is tooled • Control sealant depth – ½” maximum • Prevent 3-sided adhesion • Provide support for traffic areas Sealant Installation – Critical Success Factors
- 48. Backing Materials Recommended Materials: • Closed cell backer rod: primarily a foam material with a surface skin • Open cell backer rod: primarily a foam material without a skin • Bicellular backer rod: sometimes called “soft” rod, this foam acts like a hybrid between open and closed cell rods • Bond Breaker Tape or Backing Tape: primarily a self-adhesive polyethylene or Teflon material Sealant Installation – Critical Success Factors
- 49. Backing Materials • Make sure backer rod is 25% larger than joint width (under compression) to offer good tooling base • Do not puncture closed cell backer rod when installing prior to sealant installation • Will cause bubbling in sealant Sealant Installation – Critical Success Factors
- 50. Backing Materials • Joint Interface – The sides of the joint where the sealant is adhered. • Three-sided Adhesion – Where the sealant is adhered to the sides of the joint as well as the bottom of the joint. Sealant Installation – Critical Success Factors
- 51. • Always test for adhesion • Jobsite Pull Test: After material has cured to ensure proper bond • Test actual substrates on site • Document locations and times Adhesion Testing
- 52. Place sealant and allow to cure. Cut a 2-3” piece of the sealant and pull at a 90⁰ angle from the substrate. The sealant should not “peel” from the joint interface. Jobsite Pull Test
- 53. Specifications • 1.03 Referances ASTM Standards • 1.05 Qulaity Assurance • 2.02 Materials • 2.03 Accessories • 3.02 Joint Preperation
Editor's Notes
- While the attendees are getting seated, you can review who you are, where you’re from, and any applicable housekeeping items that need to be taken care of. A brief introduction on the company may be beneficial at this time. Family-owned and operated. Founded in 1926. Headquartered in Hampshire, IL. 10 manufacturing facilities and four warehouses strategically located around North America. Review product types/groups.
- This slide is a required slide for all AIA presentations. While this slide is on the screen review the fact that this is an accredited AIA presentation and all registered Architects are able to collect a learning point for it
- This slides meant as an introduction to the program. Here you can review the objectives of the presentation ….what you will discuss during the presentation. This slide can be read as bullet points and the points do not need to be expanded on at this time, The following slides will explain each component.
- Review of historical development of Joint Sealants. Discuss how technology has changed and what this means to the construction industry.
- Important distictions made between Caulk and Joint Sealant. Note: Service life UV resistance Weatherability
- What are the purposes of Joint Sealants. Slide can be bullet point (read) but should include discussion points. Water infiltration Air Infiltration Vapor Infiltration Sound Infiltration
- Slide explains basic usage areas for Joint Sealants.
- Slide explains basic usage areas for Joint Sealants.
- Slide explains substrate types sealed with joint sealants.
- Explination of ASTM C 920. Primary ASTM used for Polyurethane joint sealants. ASTM C719 - 14 Standard Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants Under Cyclic Movement (Hockman Cycle). ASTM C661 - 15 Standard Test Method for Indentation Hardness of Elastomeric Type Sealants by Means of a Durometer ASTM C679 - 15 Standard Test Method for Tack-Free Time of Elastomeric Sealants. ASTM C794 - 18 Standard Test Method for Adhesion-in-Peel of Elastomeric Joint Sealants
- Slide indicates the Grades and Types of Polyurethane Joint Sealants Type S- Single Component- POURTHANE SL Type M – Multi Component Grade P- Pourable / Self Leveling NS- Non-Sag Class 25= 25% movement Capability (total movement- 12.5% elongation, 12.5% contraction)
- ASTM C 719 has 5 classes. Majority of sealants used in construction fall into 25% or 35%. 100/50 indicates the material can elongate 100% and contract 50%
- Explanation of types of Joint sealant application types - Expansion Joint in pre-cast concrete
- Explanation of types of Joint sealant application types Expansion Joint between differing building material types (EFIS and Cast N Place)
- Explanation of types of Joint sealant application types Expansion Joint between differing building material types Aluminum window frame units and masonry Metal cladding and EFIS
- Explanation of types of Joint sealant application types - Expansion Joint in Masonry veneer
- Explanation of types of Joint sealant application types - Expansion Joint between metal wall panel
- Explanation of types of Joint sealant application types - Expansion Joint in PC / CNP concrete
- Explanation of types of Joint sealant application types - Expansion Joint CNP. Above waterline Below waterline
- Slide identifies common problems associated with early failure of joint selants. Key points to make Proper Joint Design Proper material type for condition Proper joint preparation (Clean, Prime, appropriate size)
- Slide provides glimpse of an adhesive failure. Typically noted in flat work (paving) where joint size is not properly designed or poor joint prep work was completed.
- Slide identifies causation points for adhesion failure as well as remediation points to correct problems
- Slide identifies causation for cohesion failure
- Substrate failure can be attributed in some cases to joint sealant failure or vise versa. In paving applications should the concrete be unsound, the subgrade shift or wash out. Failure at the joint face will be realized.
- Critical design factors to consider with joint sealants. As always every product has its limitations. For long term success of the joint the material selected must match the performance needs. In all cases a backer rod provides the best sealant shape for long term success.
- Discuss how the shape of the sealant when cured will allow for greater elongation and contraction when placed with a round backer rod installed first.
- Slide identifies why consistent and correct backer rod installation is critical.
- Key points about joint size, shape, spacing and prep.
- Slide explains the strain Joint Sealants are exposed to in expansion as well as contraction. Note that in a 2:1 WD ration the strain placed on the sealant is 62% less during periods of expansion and 230% less that in periods of contraction. During periods of Expansion strain will be placed both adhesive and cohesive. In a 1:2 WD ration adhesive failure will be expected and in a 1:1 ratio cohesive failure will be expected. During periods of Contractions critical failure will be realized in paving joints if the material is pushed up and out of the joint as vehicles drive over.
- Key points to make Select the appropriate material characteristics to meet the movement needs. Joint prep plays a more significant role in success than most contractors will admit. If critical priming should be required.
- Slide list common material types widely used today. Describe each Latex Latex sealants are water-based, easy to tool, easy to clean up, paintable, and relatively less expensive than other types of sealants. Some premium latex sealants may be appropriate for exterior use (appropriate service life) and are rated for movement in classes 12½ and 25. Latex sealants may be best suited to interior finish applications. Acrylic Acrylic sealants are also paintable but are solvent-based and more difficult to tool. They are used more in commercial and exterior applications than latex and have very limited movement capacity (Class 7½). Acrylic sealants tend to be used in commercial construction in low-movement joints. Their cost tends to be in the low to moderate range. Butyl Butyl sealants are solvent-based, synthetic rubber materials demonstrating strong adhesion to a wide variety of substrates. They have excellent weathering characteristics but tend to be stringy and difficult to apply. They generally have limited movement accommodation (less than 10%). Butyl sealants are sometimes used in curtainwall systems where adhesion to rubber materials is required. The cost of butyl sealants tends toward the moderate range. The next group are sometimes called “high-performance” sealants and are most often used in commercial building assemblies. Polysulfide Polysulfide sealants are particularly water- and chemical-resistant but do not tolerate much cyclic movement for a high-performance sealant (Class 12½ –25). Their use in buildings is most common in swimming pools and other locations where submersion must be tolerated. Polysulfide sealants often require a primer. They tend to be relatively expensive. Silicone Silicone sealants are used in a wide variety of building applications because of strong performance characteristics: UV resistance, temperature resistance, highest movement capability (Class 50–100), generally longer service life, and continued flexibility over time. Silicone sealants can have a strong odor and take considerable time to fully cure. They can be used structurally in glass assemblies. Cost for silicone sealants is in the high range. Pure silicone sealants are not paintable. Polyurethane Polyurethane sealants are tough—even abrasion-resistant. Unlike silicone sealants, they can be painted. They have excellent adhesion and good movement capability (Class 12½, 25, and 50). They can be stiff and more difficult to apply and tool than silicone and cannot be used in structural glass assemblies. As one of the “high-performance” sealants (including polysulfides and silicones), polyurethane caulks are relatively expensive. “Hybrids” – MS Polymers Hybrids are relative newcomers to the sealant world; they have chains (silyl) that modify both silicone and polyurethane sealants (MS stands for silyl-modified), combining some of the strengths of each. Their chemical profiles are better because they are solvent- and isocyanate-free So which one should I use? As with most building materials, the answer is, “It depends” match the best liquid sealant to the substrate, the application, budget, service life, compatibility to substrate, material constituency? tapes.
- Slide further defines / describes Latex Type Sealants.
- Slide further defines / describes Acrylic Type Sealants.
- Read as Bullet Points
- Good Slide to have as a hand out. Identifies that Silicone and Polyurethane sealants offer a greater range of use.
- Identify Key Differences between PU and Silicone
- Move discussion to installation practices for best success of sealants. Good point to have a table top mock up showing Joint, Joint Prep, Backer Rod Installations and sealant installation.
- Discuss cleaning practices
- Discuss priming, where and when it should be used.
- Discuss backer types Open Cell Closed Cell Flat rod / round rod Installation tools Backer rod sizeing
- Have samples on hand
- Discuss how the backer rod interacts with both the joint sealant and the substrate
- Discuss adhesive testing (field). Have demonstration in hand to provide visual aspect. Indicate when and where to include in specifications.
- Discuss adhesive testing (field). Have demonstration in hand to provide visual aspect. Indicate when and where to include in specifications.
- Make point of the following. 1.03 Referances- Specific ASTM as they pertain to relevant products. 1.05 Quality Assurance Provide materials that meet local VOC regulations. 2.02 Materials – Make point of ASTM Type, Grade, Class and Use. 2.03 Accessories- Make point of Backer rod and Primer. 3.02 Reinforce joint prep and design requirments. Provide materials that meet local VOC regulations.