VYCOR® V40 Data Sheet

40 mil, self-adhered flashing for critical non-roof detail areas

Moisture Control is the First Step to Mold Control

Water from both exterior and interior sources is among the worst enemies of building structures. When water enters the wall system and remains there for a long time, it creates an environment favorable for the development of rot, mold and mildew. Proper waterproofing and flashing practices are needed to ensure high quality, long-lasting construction.

Repairs resulting from water and moisture infiltration are major concerns for homebuilders, contractors, architects and homeowners as they are difficult repairs and extremely costly. Window and door openings, deck-to-wall intersections, foundation sill plates, corners and other penetration areas are the most common water entry points. The solution—a self-adhered flashing membrane properly integrated with the other elements of the building structure. This will create a barrier to water entry as well as a drainage plane for water to drain out of the wall.

VYCOR® V40, a high performance, self-adhered flashing membrane provides premium protection against water infiltration in all critical non-roof detail areas, which traditional building papers, felts and housewraps cannot match. When properly installed, VYCOR® V40 flashing can reduce the risk of water infiltration, often associated with costly call-backs. VYCOR® V40 flashing fully adheres to the substrate, seals around fasteners and prevents water from passing through and into the structure. It is highly conformable, easy to detail and provides premium protection against leaks. Best of all, VYCOR® V40 employs the same proven technology as our famous GRACE ICE & WATER SHIELD® —the market leader for over thirty years.

Product Advantages

  • Premium protection against air, water and moisture infiltration
  • Highly conformable
  • Protects critical non-roof detail areas including masonry walls and stucco
  • 40 mil thick

Product Description

VYCOR® V40 self-adhered flashing is composed of two waterproofing materials—rubberized asphalt and cross-laminated polyethylene. The product is designed to meet the requirements for weather-resistive barriers as defined by Federal Specification UU-B-790a, Grade A.

VYCOR® V40 is available in a range of widths: 6 in., 9 in., 12 in. and 18 in. (150 mm, 225 mm, 300 mm and 455 mm) to accommodate a variety of job requirements.


VYCOR® V40 provides protection from air, water and moisture infiltration in critical non-roof detail areas, including but not limited to:

  • Window and door openings (headers, sills, jambs, thresholds, nailing flanges)
  • Deck-to-wall intersections
  • Corner boards
  • Wall-to-wall tie-ins
  • Foundation sill plates
  • Sheathing panel seams
  • Under stucco finishes
  • Masonry walls
  • Other non-roof detail areas

Installation Procedure

Surface Preparation

Install VYCOR® V40 directly on a clean and dry surface. Some suitable surfaces include plywood, wood composition, wood plank, metal, concrete or gypsum sheathing. Remove dust, dirt and loose nails. Protrusions must be removed. Surfaces shall have no voids, damaged or unsupported areas. Repair surfaces before installing the membrane.

Priming is generally not required for most substrates provided they are clean and dry. However, on concrete, masonry and DensGlass Gold®, apply PERM-A-BARRIER® WB Primer. If adhesion is found to be marginal, also prime wood composition and gypsum sheathing with PERM-A-BARRIER® WB Primer. The coverage rate for PERM-A-BARRIER® WB Primer is 250–350 ft2/gal (6–8 m2/L).

Membrane Installation

Apply VYCOR® V40 in fair weather when the air, surface and membrane are at temperatures of 25°F (-4°C) or higher. After precipitation, allow a minimum of 24 hours for drying before installing the flashing.
Cut the membrane to appropriate length. Peel back the release liner, align the membrane, press into place and firmly roll. Laps must be a minimum of 3 in. (75 mm). Mechanically fasten the membrane at vertical terminations. Consistent with good construction practices, install VYCOR® V40 such that all laps shed water. The top membrane layer should go over the bottom layer. Always work from the low point to the high point.

Precautions and Limitations

VYCOR® V40 is designed for non-roof detail areas. This product is slippery—DO NOT walk on the membrane.
Do not leave VYCOR® V40 permanently exposed to sunlight. Maximum recommended exposure is 30 days.
VYCOR® V40 should not be used in hot desert areas in the southwestern United States.
Due to its slight asphaltic odor, apply VYCOR® V40 where it is not exposed to interior living space. The product is incompatible with creosote, joint sealants containing polysulfide polymer, products manufactured from EPDM, flexible PVC, as well as certain caulks. Refer to Tapes Technical Letter 1, Chemical Compatibility, for further details. Contact window manufacturer for specific application instructions required when using a self-adhering, bituminous-based flashing. Certain metal window applications with integral nailing fin may have specific limitations. For more information, contact your local GCP technical sales representative.

For more information, check with your local GCP Applied Technologies technical sales representative.


Complies with the requirements of AAMA 711 for self adhered flashing materials.

Product Data

Product thickness 40 mil (1.02 mm)
Carrier frilm Cross-laminated HDPE
Adhesive Rubberized asphalt
Release liner Paper
Color Black-grey
Recommended exposure limit 30 Days
Shrink Wrapped Rolls
Roll width(s) 4 in. (100 mm) 6 in. (150 mm) 9 in. (225 mm) 12 in. (300 mm)
Roll length(s) 50 ft (15.2 m) 50 ft (15.2 m) 50 ft (15.2 m) 50 ft (15.2 m)
Rolls per carton 18 12 6 6

Physical Properties

Property VYCOR® V40 self-adhered flashing Test Method
Water vapor permeance 0.02 perms ASTM E96, Method B, wet cup
Air permeance at test pressure of 1.57 psf (75 Pa) < 0.001 L/(s/m2)(<0.0002 cfm/ft2) ASTM E2178
Peak Load, MD/XD (lbf/inch) 25 lbf/ inch in MD, 22 lbf/ inch in CMD ASTM D5147
Ultimate Elongation, MD/XD (%) 200% in MD, 400% in CMD ASTM D5147


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We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

VYCOR, ICE & WATER SHIELD, and PERM-A-BARRIER are trademarks, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. DensGlass Gold is a registered trademark of Georgia-Pacific Corporation. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

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Last Updated: 2023-06-28