A Different Type of Stainless-Steel Flashing

A Different Type of Stainless-Steel Flashing

Written by Katie Burrell, with support from Danielle Jackson of York Flashings

Division 076200 – Sheet Metal Flashing and Trim – is a typically used specification for cavity and through-wall flashings in commercial and residential buildings. It includes familiar metal flashing types, covering galvanized steel, copper, stainless steel, aluminum, and describes them as 'sheet' materials to be bent into flashing profiles. This section is closely related to the sheet metal roofing specification (076100) and the Roof Specialties spec (077100), which also covers copings, reglets and counterflashing.

These formed metal flashings can be used within exterior cavity walls with many different façade systems. Stainless steel is seen as the gold-standard for through-wall and cavity-wall flashing, as it is strong, compatible with most other building materials and resists corrosion. Fluoropolymer (color) coated aluminum is extremely useful for matching adjacent surfaces (like siding or windows).

There are some drawbacks to consider, however. Stainless steel does not color match adjacent materials – and could be prohibitively expensive. Aluminium and zinc flashing cannot be used in contact with pressure treated wood due to rapid corrosion. Aluminium can also be damaged by wet mortar and wet plaster in masonry walls.

So, is there another option?

Have you considered flexible flashings?

Flexible flashing is usually synonymous with transitions – tapes, window and door openings, tough areas where the malleability of the flashing aids in making complex shapes. These are typically considered non-metallic and include both peel-and-stick and nonstick flashings. However, there is another type of flexible flashing material that can be found if you know where to look. Check out 04200 – Unit Masonry or 042613 – Masonry Veneer and you'll see an 'Embedded Flashing' section, which lists flexible metal and metal/fabric-bonded flashing options. But these are within Division 04 in the masonry specification. Are they useful for other wall types? In short – YES.

The most simple and versatile flexible metal flashing type is the equivalent of a thin, flexible stainless-steel sheet.

Flexible stainless-steel flashings are significantly less expensive in both material and labor costs compared to rigid sheet metal flashings, without compromising on performance characteristics. It can also be bonded to other materials, creating a hybrid material with some useful properties. Self-adhering products (meaning no additional adhesive product is needed for installation) are also available.

In general, flexible stainless-steel flashings offer the following benefits.

•                    Life of the wall warranty

•                    Best in class puncture/tear resistance (2500+ PSI)

•                    UV Resistant

•                    Heat resistant (for spray foam insulation)

•                    ASTM E84 Class A fire resistance

•                    Compatible with all weather barriers and sealants

•                    Flexible and can conform to varying site conditions

•                    Forms by hand and does not require any metal bending tools

•                    End dams and corners can be folded on site if desired

•                    Low scrap due to the ability to form on site

Specific types of flexible stainless-steel flashings and their uses include:

Self-Adhering Stainless Steel (ex: York 304 SA) is designed with a flexible, 2 mil sheet of Type 304/316 stainless steel, butyl adhesive, and a siliconized release liner. This product offers excellent adhesion to a variety of surfaces and does not require a primer. It comes in a variety of widths to accommodate a variety of applications. This product has a 20-year warranty (due to the self-adhesive). It passes AAMA 711-20 and ASTM E2178-13. Common Applications: Through-wall flashing, transition membrane, jamb closure and fenestration flashing, window and door sill pan, repair tape, lap tape, and deck ledger flashing.

Stainless Steel Fabric Flashing (ex: Multi-flash SS) is designed with a flexible 2 mil sheet of Type 304/316 stainless steel laminated on one side to a polymer fabric. 60' rolls allow for fewer lap joints. This product offers a life of the wall warranty. Common Applications: Through-wall flashing, transition membrane, window and door sill pan, deck ledger flashing.

Stainless Steel Drainage Plane Flashing (ex: Flash-Vent SS/SA) is designed with a flexible 2 mil sheet of Type 304 stainless steel laminated on one side to a polymer fabric and drainage fabric on the opposite side. This product offers continuous drainage, does not clog with mortar which allows the elimination of mortar netting, and the non-self-adhesive product has a life of the wall warranty. Common Applications: Through-wall flashing in cavity walls, stucco, manufactured stone, and thin brick.

Wondering about required support within the wall cavity for these flashing types? Flexible SS flashings are capable of spanning unsupported gaps up to six inches in width. But note that if the flexible SS flashing is spanning a cavity, it must be continuous with no lap joints, secured mechanically to the backer wall, sloped toward the exterior and fastened securely at the leading exterior edge to prevent mortar droppings or netting devices from applying enough pressure to pull the flashings down into the cavity. 

While all of these types can be used in masonry cavity walls, they are versatile enough to be used in other applications, as well, and can be found in Division 07 specification sections.

So, do your research and be specific in your drawings so that you can correctly identify the types of flashing, where to use them and how they can be tied back to your specifications.