R-Guard FastFlash Liquid Flashing & Waterproofing Compound

R-Guard FastFlash – Single-Component Liquid Flashing Membrane for Seamless Waterproofing

PROSOCO R-Guard FastFlash is a single-component, silyl-terminated polymer (STP) waterproofing, adhesive, and detailing compound engineered for contractors and trades professionals working on air barrier and waterproofing applications. It produces a seamless, elastomeric flashing membrane that is highly durable and suited for use in both new construction and existing wall assemblies. FastFlash is designed for use in rough openings, joints and seams, counterflashing, penetration sealing, and countersunk fastener protection. As part of the R-Guard product line, it is formulated to meet the demands of professional building envelope work.

FastFlash combines the best characteristics of silicone and polyurethane in a single-component STP chemistry, eliminating the need to choose between the flexibility of silicone and the adhesion characteristics of polyurethane. It can be gun-applied, spread, tooled, or roller-applied, giving installers the flexibility to adapt to a wide range of field conditions and substrate geometries without switching products.

Key Features & Benefits

Silyl-Terminated Polymer (STP) Chemistry

FastFlash's STP chemistry merges the properties of silicone and polyurethane into one product, delivering the flexibility and weather resistance of silicone alongside the strong adhesion of polyurethane. For contractors, this means a single material handles the full range of detailing and flashing tasks without compromising on either adhesion or long-term elasticity.

Single-Component Formulation

As a single-component product, FastFlash requires no mixing on the jobsite, reducing the risk of ratio errors and simplifying installation workflow. This saves time during setup and helps ensure consistent performance across the entire application area.

Seamless, Elastomeric Membrane

Once applied, FastFlash cures to form a seamless, elastomeric membrane that accommodates movement without cracking or losing adhesion. This is particularly important at joints, seams, and rough openings where substrate movement or thermal cycling is expected.

Versatile Application Methods

FastFlash can be gun-applied, spread, tooled, or roller-applied, making it adaptable to a wide range of detailing scenarios from tight rough openings to broad flashing areas. This flexibility reduces the need for multiple products on the jobsite.

Low VOC Content

FastFlash has a VOC content of less than 30 g/L, well within the SCAQMD 1168 architectural sealant limit of 250 g/L, and is compliant with the California Air Resources Board (CARB) 2007 requirements. It is also CDPH Standard Method v1.2-2017 compliant, with total VOCs after 14 days at 0.5 mg/m³ or less, supporting use in projects pursuing LEED, Living Building Challenge, WELL, and other green building certifications.

Green Building Program Compatibility

FastFlash carries a Declare label (PRO-0003) and has been confirmed Red List Free under the Living Building Challenge 3.0, making it suitable for the most stringent material transparency requirements. It also holds SCS Indoor Advantage Gold certification for low-emitting materials compliance under LEEDv4.

Common Applications

Rough Opening Waterproofing

FastFlash is applied as a liquid flashing membrane in rough openings around windows and doors to create a continuous, watertight seal before unit installation.

Joint and Seam Filling

Use FastFlash to fill joints and seams in wall assemblies, forming a flexible, seamless bond that prevents water infiltration at these critical transition points.

Counterflashing for Waterproofing and Air Barrier Components

FastFlash can be used to counterflash waterproofing and air barrier components in both new and existing wall assemblies, ensuring continuity of the building envelope at transitions and terminations.

Penetration Sealing

Apply FastFlash around mechanical, electrical, and plumbing penetrations to create a durable, watertight and airtight seal at each pass-through.

Countersunk Fastener Protection

FastFlash can be applied over countersunk fasteners to protect against water intrusion at each fastener location, preventing long-term moisture damage to the substrate.

Compatible Materials

• Wall sheathing (new and existing assemblies)
• Air barrier components
• Waterproofing membranes
• Substrates at rough openings (windows and doors)
• Joints and seams in wall assemblies
• Penetration sleeves and flashings

Product Documents

• Product Data Sheet
• Product Data Sheet (Canadian French)
• Product Data Sheet (Spanish)
• Safety Data Sheet
• Safety Data Sheet (Spanish)
• Safety Data Sheet (Canadian French)
• VOC Compliance
• Product Test Data – ASTM E2357
• Product Test Data
• LEED Verification Letter
• SCS Certification
• LBC Red List Conformant Product Summary
• LBC Red List Conformant Product Summary (May 2021)

Technical Specifications

Frequently Asked Questions

Q: Can FastFlash be used on both new construction and existing wall assemblies?
A: Yes. FastFlash is suitable for use in new construction and for counterflashing waterproofing and air barrier components in existing wall assemblies.

Q: Is FastFlash compliant with green building certification programs?
A: FastFlash supports documentation for LEED 2009, LEED v4.x, CALGreen, Living Building Challenge 3.x, WELL v2, and Fitwel. It is CDPH Standard Method v1.2-2017 compliant, CARB 2007 compliant, carries SCS Indoor Advantage Gold certification, and is confirmed Red List Free under the Living Building Challenge.

Q: What application methods are supported?
A: FastFlash can be gun-applied, spread, tooled, or roller-applied, providing flexibility for a wide range of field conditions and substrate types.

Q: Does FastFlash require mixing before use?
A: No. FastFlash is a single-component product and requires no on-site mixing, simplifying application and reducing the risk of errors.