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STPE Sealants: What You Need to Know

Silyl Terminated Polyether (STPE) sealants combine the weather resistance of silicone and the strength of polyurethane to create a long-lasting sealant with superior strength, flexibility, and adhesion. STPE sealant bonds to most construction materials (masonry, stone, concrete, wood, fiber cement, vinyl, stucco) for joint sealant applications, like around wall penetrations, fixtures, floor lines, etc.

A tight building envelope keeps outside elements (primarily air and moisture) from infiltrating a structure. Correctly applying a high-performing STPE joint sealant, like StoSeal STPE™Sealant, provides a critical step towards weatherproofing a building’s exterior and protecting its integrity and health.

Why Buildings Need High-Performing Sealants

Achieving a tight building envelope requires strategic air sealing of major gaps. ASHRAE research identified five critical locations that require air sealing based on ACH50 reduction. ACH50 stands for air changes per hour at 50 pascals pressure differential. It represents the number of times the air volume in a building changes per hour at 50Pa of pressure – a significant measure of a building’s energy efficiency.

1. The top plate to attic drywall achieves a potential ACH50 reduction: up to 1.6 exchanges – the greatest impact of all locations.
2. Recessed can lights to the finished surface achieve a potential ACH50 reduction: 0.2+ exchanges.
3. Duct boot to finished surface achieves a potential ACH50 reduction: 0.2+ exchanges.
4. Band joist (top and bottom) achieves a potential ACH50 reduction: 0.4 exchanges.
5. Between the house and garage’s wall achieves a potential ACH50 reduction: 0.2+ exchanges.

The Benefits of STPE Sealants

STPE technology creates sealants that have several high-performance features compared to silicone and polyurethane sealants:

Flexibility: STPE sealants’ elongation characteristics can endure structural movement and withstand substrate vibrations or oscillations more effectively than silicone sealants.
Adhesion: STPE sealants adhere more effectively to various substrates, like concrete, wood, plastics, ceramics, and metals, compared to polyurethane and silicone sealants.

UV Resistant: STPE sealants will not crack or yellow after extended periods of UV-light exposure, unlike polyurethane sealants.

Environmentally Friendly: STPE products contain extremely low or no VOCs, unlike other sealants prone to off-gassing.

Weather Resistant and Durable: STPE sealants perform well at low temperatures and in most weather conditions, from dry to extremely wet and rainy, with no splitting, cracking, discoloration, or adhesion failures.

Easy Application: STPE sealants do not require priming (unlike silicone and polyurethane ) and can create a continuous smooth surface that you can paint after 24 hours.

Cure Rate: STPE sealants cure quickly, even at low temperatures.

Cold Resistant: STPE sealants retain their properties to -50°F (-45°C).

Non-Reactive: STPE sealants will not corrode or oxidize metals.

Storage Stability: When not exposed to moisture, STPE sealants have an excellent shelf life.

StoSeal STPE™ Versatile, High-Performance Adhesive Sealant

Sto Corp. recently launched StoSeal STPE™ Sealant – a high-quality, low-odor, isocyanate-free, one-part hybrid sealant with a VOC content of 8 grams per liter. Durable, low-modulus, non-sag, and flexible StoSeal STPE™ Sealant provides superior moisture and weathering resistance.

StoSeal STPE™ Sealant’s excellent adhesive properties work effectively with StoTherm® ci, StoPowerwall®, StoQuik®, and StoVentec® exterior wall systems and with StoGuard® air- and water-resistive barrier system for vertical above-grade new opaque wall and building restoration applications. You can use it for panel-to-panel joints in prefabricated construction, interior use, metallic and cementitious substrates, storefront systems, air sealing applications, and concrete repair.

Benefits and features of StoSeal STPE™ Sealant include:

  • High-Movement: Offers +100%/-50% movement – suitable for low and high movement joints
  • Simplifies installation
    • Primer-free bonding to most substrates
    • Easy to gun and tool
    • Fast, tack-free cure times
    • Packaged in 20-ounce sausages that minimize construction waste and provide efficient installation
  • Paintable with Elastomeric Coatings
    • Available in ten standards and over 300 custom colors
    • Allows for top coating with elastomeric coatings to suit most color requirements
  • Excellent Adhesion: It will bond to most construction materials without a primer
  • Durable, Long-Lasting: StoSeal STPE™ Sealant offers superior moisture-, UV-, weathering-, aging-, and shrink-resistance
  • Environmental-Friendly: StoSeal STPE™ Sealant lacks Isocyanate-free and contains very low VOC – it will not bubble and releases very little odor
  • Storage Stable: When properly stored, the sealant will last 12 months in original, unopened packaging

StoSeal STPE™ Sealant Compliance Testing

StoSeal STPE™ Sealant conforms to, or tests according to the:

  • ASTM C920: Type S, Grade NS, Use NT, A, M, Class 100/50
  • Federal Spec. TT-S-00230C Type II
  • AAMA 808.3 (Type1) Exterior Perimeter Sealing
  • ASTM C1382 for use with EIFS

Where to Use StoSeal STPE™ Sealant

StoSeal STPE™ Sealant bonds to most common construction materials, including masonry, concrete, stone, stucco, fiber cement, aluminum, steel, wood, and vinyl. You can use it for various applications in Sto proprietary wall systems and other wall assemblies. Examples of applications include:

Thermal expansion and contraction joints

  • Control joints
  • Panel-to-Panel joints between precast, metal frame, and other prefabricated wall construction
  • Deflection joint sealant at floor lines
  • Air seal at interior or exterior joints and seams for air barrier continuity
  • Perimeter weather seal around windows, doors, scuppers, and other through-wall penetrations
  • Perimeter weather seal around fixture attachments
  • Bedding sealant for flashing, flanged windows, and related applications

Why Choose StoSeal STPE™ Sealant?

Air sealing the joints, penetrations, and other gaps in a building envelope with high-performing StoSeal STPE™ Sealant can significantly contribute towards a tight building envelope. A tight building envelope protects a building’s integrity and increases the occupant’s comfort level by preventing moisture, drafts, and unwanted noise from infiltrating the building. In addition, the sealant can also improve indoor air quality by minimizing mold and pollution exposure, and can lessen energy use and save money.

Durable, weather-resistant, flexible, and non-toxic StoSeal STPE™ Sealant offers superior adhesion when applied to vertical above-grade new opaque walls and building restorations.

For more on what you need to know about StoSeal STPE™ Sealants, contact our professionals today at (800) 221-2397.

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