Board Seam Filler WB - Pallet of 900 Pieces (20oz Sausages)

Board Seam Filler WB — Acrylic Gun-Grade Seam Filler for Continuous Air Barrier Systems

Technical Specifications

PROSOCO R-Guard Board Seam Filler WB is an acrylic, gun-grade, water-based paste formulated to fill board seams in exterior sheathing assemblies. It is designed for use by contractors building continuous air barrier systems, applied in the field before coating over with R-Guard FastFlash or any PROSOCO R-Guard air barrier coating. The single-component, paste consistency makes it easy to gun, spread, and tool directly from a sausage pack using a standard professional caulking gun.

Unlike solvent-based or two-component alternatives, Board Seam Filler WB is solvent-free, isocyanate-free, and phthalate-free, simplifying job site safety and cleanup. Its breathable, water-based acrylic formula allows damp substrates to continue drying after application, and the cured film can withstand direct UV and weather exposure for up to 12 months.

Key Features & Benefits

Water-Based Formula — Easy Cleanup

Board Seam Filler WB cleans up with water, eliminating the need for solvents on the job site. This reduces material costs and simplifies compliance with site safety requirements.

Single-Component — No Mixing Required

The ready-to-use, single-component formula saves time and eliminates the risk of mixing errors. Contractors can move directly from setup to application without additional preparation steps.

Bonds Without Priming

Board Seam Filler WB bonds to most common building materials without requiring a separate primer step. This reduces labor time and the number of products needed on the job site.

UV and Weather Resistant Up to 12 Months

The cured product may be fully exposed to UV and weather for up to 12 months, providing flexibility in construction scheduling before the final air barrier coating is applied.

Breathable — Allows Damp Surfaces to Dry

The breathable formula does not trap moisture beneath the film, allowing damp substrates to continue drying after application. This is particularly valuable in assemblies where perfect surface dryness is difficult to guarantee.

Solvent-Free, Isocyanate-Free, Phthalate-Free

The clean-chemistry formula contains no solvents, isocyanates, or phthalates. This reduces health and safety concerns during application and supports projects with stringent chemical restriction requirements.

Will Not Support Mold Growth

The cured film will not support mold growth, contributing to long-term wall assembly performance and durability.

Low VOC — EPA AIM Compliant

With a VOC content of 25 g/L maximum, Board Seam Filler WB is compliant with the U.S. EPA's AIM VOC regulations. Contractors should confirm compliance with individual state or district regulations via the PROSOCO VOC compliance documentation.

Common Applications

Board Seam Filling in Air Barrier Systems

Apply to seams between sheathing boards in the field as part of a continuous, building-wide R-Guard air barrier system, prior to coating with R-Guard FastFlash or other R-Guard air barrier coatings.

Insulated Concrete Form (ICF) Seams

Board Seam Filler WB may be used to fill seams in ICF assemblies as part of an R-Guard air barrier installation.

Exterior Sheathing Seam Treatment

Used to address field seams in exterior sheathing before the application of an air barrier coating, ensuring continuity across the building envelope.

Compatible Materials

• Most common building materials (without priming)
• Gypsum board (exposed cut edges should be prepared with R-Guard PorousPrep)
• Insulated Concrete Form (ICF) substrates
• Substrates compatible with R-Guard FastFlash and R-Guard air barrier coatings

Limitations

• Not for use in dynamic joints, rough openings, or other penetrations
• Do not apply to contaminated or damp surfaces
• Keep product from freezing; freeze point is 32°F (0°C)
• Not for application at surface or air temperatures below 40°F (5°C) or above 100°F (38°C)
• Protect from rain for at least 12 hours at 70°F (21°C) and 50% relative humidity, or until fully cured
• Not for use as a liquid flashing membrane — use R-Guard FastFlash instead
• Not for use in place of appropriate through-wall flashing — see R-Guard SS ThruWall product literature
• Not for use below grade or in locations continuously immersed in water
• May have slight incompatibility with some asphaltic materials or butyl adhesives — always test first

Product Documents

• Product Data Sheet
• Safety Data Sheet
• Safety Data Sheet (Spanish)
• SDS Canadian French
• VOC Compliance

Application Instructions

Surface Preparation

1. Apply only to clean, dry surfaces free of contaminants. Chemical residues, surface oxidation, surface coatings, or films may adversely affect adhesion.
2. Remove and replace any damaged sheathing before proceeding.
3. Prepare exposed, cut gypsum board edges with R-Guard PorousPrep prior to application.
4. Protect people, vehicles, property, plants, and all surfaces not intended to receive Board Seam Filler WB.
5. Ensure roofing systems are capped and sealed, or the top of walls is protected from water intrusion both before and after air barrier system installation.

Temperature Conditions

1. Apply only when substrate and air temperatures are between 40°F (4°C) and 100°F (38°C).
2. Surface temperatures must remain at least 40°F (4°C) and rising after application until curing is complete.
3. In hot weather (air or surface temperatures exceeding 95°F / 35°C): apply to the shady side of the structure before daytime temperatures peak. Hot surfaces may be cooled with a mist of fresh water. Keep containers closed and out of direct sunlight. Cover open pails with plastic to prevent skinning.
4. In cold weather: store material in a heated environment prior to use. Apply only to frost-free substrates at temperatures of 40°F (4°C) or above.

Application — Sausage Pack

1. Load the 20-oz sausage pack into a professional caulking gun.
2. Apply Board Seam Filler WB to the seam.
3. Use a joint knife, trowel, or spatula to tool and spread the product as needed.
4. Protect the applied product from rain for at least 12 hours at 70°F (21°C) and 50% relative humidity, or until fully cured.
5. After curing, proceed with application of R-Guard FastFlash or the specified R-Guard air barrier coating over the treated seams.

Storage & Handling

1. Keep product from freezing. Store in a cool, dry place.
2. Keep container tightly closed when not dispensing.
3. Do not open container until preparation work has been completed.
4. Shelf life is 1 year in a tightly sealed, unopened container.

Safety Data Summary

Hazard Information

• Not classified as a dangerous substance or mixture according to the Globally Harmonized System (GHS)
• May cause irritation to eyes, skin, and respiratory tract
• Do not allow product to enter sewers, ground, or any body of water

Personal Protective Equipment

• Eyes: Wear safety glasses with side shields or goggles
• Skin: Wear appropriate protective gloves; wash with soap and water after contact
• Inhalation: Ensure adequate ventilation; remove to fresh air if vapors or mists are inhaled

Safe Handling

• Handle in accordance with good industrial hygiene and safety practices
• Avoid contact with skin, eyes, or clothing
• Avoid breathing vapors or mists
• Keep containers tightly closed in a dry, cool, and well-ventilated place
• Keep out of reach of children
• Do not induce vomiting if ingested; rinse mouth and call a physician
• 24-Hour Emergency Information: INFOTRAC at 800-535-5053
• Business hours emergency: 785-865-4200 (8:00 AM – 5:00 PM CST, Monday–Friday)

Frequently Asked Questions

Q: Can Board Seam Filler WB be used as a standalone air barrier or liquid flashing membrane?
A: No. Board Seam Filler WB is specifically a seam filler used as part of a continuous R-Guard air barrier system. It is not for use as a liquid flashing membrane — R-Guard FastFlash should be used for that purpose. It must be topcoated with R-Guard FastFlash or another R-Guard air barrier coating.

Q: Can Board Seam Filler WB be applied to ICF seams?
A: Yes. The product may be used on Insulated Concrete Form (ICF) seams as part of an R-Guard air barrier installation.

Q: How long can the applied product remain exposed before the air barrier topcoat is applied?
A: Board Seam Filler WB may be fully exposed to UV and weather conditions for up to 12 months before the topcoat is applied.

Q: What is the minimum application temperature?
A: Do not apply at surface or air temperatures below 40°F (4°C). Surface temperatures must remain at 40°F (4°C) or above and rising after application until curing is complete. The product must also be protected from freezing during storage, as its freeze point is 32°F (0°C).

Q: Does Board Seam Filler WB require a primer on common building materials?
A: No. The product bonds to most common building materials without priming. However, exposed cut gypsum board edges should be prepared with R-Guard PorousPrep before application.

Q: How long must the applied product be protected from rain after application?
A: Protect from rain for at least 12 hours at 70°F (21°C) and 50% relative humidity, or until fully cured.