NOTE A drained masonry wall is not waterproof. The outer wythe of brick, stone, or architectural CMU is a reservoir cladding: it absorbs and transmits liquid water during wind-driven rain. The wall sheds that water by intercepting it on a flashing, draining it laterally to weep openings, and expelling it back to the exterior face. Through-wall flashing is the horizontal interception surface in that system, and it is useless without the cavity, weeps, and end dams that complete the drainage path. (1.2)

NOTE The included scope is enumerated so the Contractor and Engineer can confirm one section owns each component of the drainage path. (1.4)

NOTE This standard covers flashing materials, geometry, and terminations; weep and vent systems; cavity drainage media; lap and end-dam details; and coordination of the flashing with the wall backup air/water-resistive barrier. (1.4.1)

NOTE The covered locations are base-of-wall, lintel and shelf-angle, sill, head, and parapet conditions, plus any horizontal interruption where masonry abuts other construction. (1.4.2)

NOTE Exclusions are stated as boundaries, not obligations, so that responsibility is unambiguous where this standard meets adjacent trades. (1.6)

NOTE Roofing edge metal, coping counterflashing, and roof-to-wall terminations are excluded and are governed by Sheet Metal Flashing And Trim. (1.6.1)

NOTE Air/water-resistive barrier membrane products and continuity are excluded and are governed by Air Barriers; this standard coordinates with the WRB but does not specify it. (1.6.2)

NOTE Masonry veneer ties, anchors, and shelf-angle structural design are excluded and are governed by Masonry Anchorage And Veneer. (1.6.3)

NOTE Below-grade and under-slab self-adhered sheet waterproofing is excluded and is governed by Self Adhering Sheet Waterproofing. (1.6.4)

NOTE Wall sheathing and its housewrap/WRB facing are excluded and are governed by Wood Sheathing. (1.6.5)

NOTE Window and door sill-pan flashing installed as a fenestration sub-component is excluded; coordinate the integration of fenestration pan flashing with this through-wall flashing per ASTM E2112 and AAMA 711. (1.6.6)

NOTE The boundary between this standard and Sheet Metal Flashing And Trim is the function of the metal. (1.7)

NOTE Flashing that is embedded in the masonry wall assembly to perform a through-wall drainage function is owned here, regardless of whether it is metal or membrane. Exposed edge metal, counterflashing, and roofing terminations are owned by the sheet-metal standard. A metal drip edge that receives membrane flashing is owned here because its function is drainage, not roofing. (1.8)

NOTE The current governing masonry code is TMS 402/602-22, referenced by the 2024 IBC; many jurisdictions remain on the 2021 IBC, which references TMS 402/602-16. (2.2)

NOTE The writer of a project specification shall confirm the adopted code edition with the authority having jurisdiction, because weep-spacing and flashing-location language differs slightly between TMS editions. (2.3)

NOTE Action submittals establish the materials and details the Engineer reviews before the flashing is built into the wall, where it becomes permanently concealed and uninspectable. (3.2)

NOTE Informational submittals support quality assurance but do not, by themselves, gate fabrication. (3.4)

NOTE Closeout submittals document the as-built drainage system for the building owner's future maintenance and any warranty claim. (3.6)

NOTE Concealed flashing cannot be repaired without demolishing the wall, so installer competence is the primary defense against latent leakage. (4.2)

NOTE A mock-up resolves material-compatibility and lap-sequence questions before they are buried in the production wall. (4.4)

NOTE ASTM E514 is a laboratory method; a field-adapted version of its driving-rain load is the most direct way to confirm that a built assembly drains rather than retains water. (4.6)

NOTE Because flashing is concealed course by course, inspection must occur while each flashing run is still exposed. (4.8)

NOTE Flashing material selection follows from the severity of wetting and thermal exposure at each location. (5.2)

NOTE The flashing material at each location shall be selected for the wind-driven-rain exposure, freeze-thaw exposure, and ultraviolet exposure of that location, with base-of-wall and parapet conditions treated as the most severe. (5.2.1)

NOTE Base-of-wall flashing collects the entire column of water draining down the cavity and sits in the zone of splash, snow, and de-icing salt. Parapet flashing is exposed on two faces and undergoes the widest thermal swing of any wall location. (5.2.2)

NOTE A drainage cavity that is too narrow bridges with mortar and stops draining; minimum clear width is a code requirement, not a preference. (5.4)

NOTE The four material families each carry a different cost, durability, and compatibility profile; the choice drives nearly every downstream detail. (6.2)

NOTE Through-wall flashing material shall be one of: sheet metal (copper, stainless steel, or galvanized steel); EPDM membrane; rubberized-asphalt (SBS) self-adhered membrane; or composite metal-laminate membrane. (6.2.1)

NOTE Metal flashing is the most durable and is preferred where it terminates at an exposed drip; membrane flashings are more forgiving of complex geometry and laps but require a metal drip edge at the face. Composite laminates pair a thin metal foil with a self-adhered membrane to combine the two. (6.2.2)

NOTE Aluminum shall not be used as masonry flashing in contact with mortar. (6.2.3)

NOTE Portland-cement mortar is strongly alkaline; it corrodes aluminum rapidly. This is the single most common material-selection error in masonry flashing and is non-negotiable. (6.2.4)

NOTE Metal thickness governs the flashing's resistance to puncture during construction and to long-term fatigue at the drip. (6.4)

NOTE EPDM is a flexible, UV-tolerant membrane well suited to base-of-wall runs and irregular geometry. (6.6)

NOTE SBS self-adhered membrane bonds aggressively to the backup but is vulnerable to ultraviolet light and to incompatible sealants. (6.8)

NOTE Rubberized-asphalt flashing shall not be exposed at the face of masonry. (6.8.2)

NOTE Ultraviolet exposure and thermal cycling delaminate exposed SBS membrane and bleed a dark stain onto the masonry face. SBS flashing shall always terminate behind a metal drip edge. (6.8.3)

NOTE Most masonry flashing failures that are not installation errors are chemical-compatibility errors between the flashing and an adjacent material. (6.10)

NOTE Solvent-based and coal-tar sealants shall not be used against rubberized-asphalt membrane, and bitumen-based products shall not be used against EPDM. (6.10.2)

NOTE Solvent and coal-tar chemistries attack SBS membrane, and bitumen plasticizers migrate into and degrade EPDM. The compatible sealant family shall be specified explicitly rather than left to the field. (6.10.3)

NOTE Dissimilar metals in contact shall be isolated with bituminous paint or polyethylene tape to prevent galvanic corrosion. (6.10.4)

NOTE Copper flashing against galvanized-steel shelf angles or aluminum window frames forms a galvanic couple that corrodes the less-noble metal. Copper mortar contact can also bleed a green stain; mortar at copper flashing shall comply with ASTM C1329 composition limits. (6.10.5)

NOTE The drip edge is the feature that actually returns water to the exterior; without a projecting drip, water tracks back under the flashing onto the wall below. (7.2)

NOTE The flashing shall extend to the face of masonry and terminate in a drip edge that projects a minimum of 1/4 in. (6 mm) beyond the face per TMS 602 and BIA. (7.2.1)

NOTE A projection of 3/8 in. is the common default with a metal drip edge, and a larger projection sheds water further from the face below; the 1/4 in. minimum is the code floor, not the target. (7.2.2)

NOTE The turned-up leg is the dam that forces collected water out to the cavity rather than over the back of the flashing into the backup. (7.4)

NOTE Flat or back-sloped flashing holds water against the backup and feeds it into the wall instead of out the weeps. (7.6)

NOTE Field splices are where the most leaks occur because they receive less care than shop-fabricated lengths. (7.8)

NOTE End dams close the ends of a flashing run so that laterally draining water cannot run off the end and back into the wall. (7.10)

NOTE Weeps are the only exit for water that the flashing collects; their type and spacing determine whether the wall actually drains. (8.2)

NOTE Weep openings shall be provided in the head joints of the first masonry course immediately above every horizontal flashing location, including base of wall, lintels, shelf angles, and sills. (8.2.1)

NOTE Omitting weeps above a lintel or shelf angle is a common error that traps water on the flashing and produces efflorescence and freeze-thaw spalling at that course. (8.2.2)

NOTE The weep type trades off drainage capacity, insect resistance, and appearance. (8.4)

NOTE The weep type shall be open head joints, plastic or wire weep-tube inserts, or manufactured weep vents, selected for the required drainage capacity and the project's insect and appearance requirements. (8.4.1)

NOTE Open head joints drain fastest but admit insects unless screened or vented with an insert; tube inserts and manufactured vents restrict insects at some cost to drainage rate. (8.4.2)

NOTE Code sets a maximum spacing; the common project default is tighter to improve drainage and tolerance for blocked weeps. (8.6)

NOTE Venting the top of the cavity in addition to weeping the base promotes airflow that helps dry the cavity between wetting events. (8.8)

NOTE Mortar that falls into the cavity and piles on the flashing bridges the cavity and dams the weeps; controlling it is as important as the flashing itself. (9.2)

NOTE A cavity drainage medium shall be installed in the cavity directly above the flashing to keep mortar droppings off the flashing and maintain the weep drainage path. (9.2.1)

NOTE A mortar net, cavity drainage mat, or drainage mesh of polyamide or polypropylene holds mortar droppings above the flashing so water still reaches the weeps. Omitting this medium from the specification while showing it only on a detail is a frequent source of RFIs and field disputes. (9.2.2)

NOTE Excess mortar squeezed from the flashing bed joint can block weeps even when a drainage medium is present. (9.4)

NOTE The through-wall flashing and the backup WRB must form one continuous drainage plane; a gap or a reversed lap between them feeds water into the wall. (10.2)

NOTE The flashing turned-up leg and the WRB shall terminate on the same plane of the backup wall and shall be lapped so that water is directed outward, with the flashing lapped over the WRB leg in shingle fashion unless the WRB manufacturer's tested detail directs otherwise. (10.2.1)

NOTE The default shingle order is flashing over WRB so that water on the flashing cannot run behind the membrane below. Some tested WRB systems reverse this at specific transitions; where they do, the manufacturer's tested detail governs. Coordinate the membrane specification itself with Air Barriers. (10.2.2)

NOTE The base-of-wall flashing is the most heavily loaded run in the wall and the one most often compromised by mortar fill. (11.2)

NOTE Base-of-wall flashing shall be installed continuously at the bottom of the drained cavity, turned up against the backup per the turned-up-leg requirement, with weeps and cavity drainage medium at the first course above. (11.2.1)

NOTE The base-of-wall flashing receives the cumulative drainage of the entire wall above it, so its end dams, slope, and weep continuity are the highest-consequence details in the assembly. (11.2.2)

NOTE Every horizontal structural interruption of the veneer is a new collection point that needs its own flashing, weeps, and end dams. (11.4)

NOTE Flashing shall be installed over every lintel and shelf angle, turned up against the backup a minimum of 6 in. (150 mm), with end dams at each end and weeps in the course above. (11.4.1)

NOTE A shelf angle interrupts the continuous cavity and supports the veneer above it; water draining down the cavity reaches the shelf angle and must be intercepted and expelled there rather than continuing past it. (11.4.2)

NOTE Sill flashing protects the wall below window and other openings, where concentrated runoff from the opening above is common. (11.6)

NOTE Head flashing intercepts water above an opening before it can enter the head of the frame below. (11.8)

NOTE Parapets are exposed on two faces and are the wall condition most prone to flashing failure from thermal movement and freeze-thaw. (11.10)

NOTE Parapet through-wall flashing shall be installed below the coping bed and coordinated with the coping counterflashing, which is specified under Sheet Metal Flashing And Trim. (11.10.1)

NOTE The through-wall flashing under the coping is owned by this standard because its function is to drain the cavity; the coping cap and its counterflashing are roofing-edge metal owned by the sheet-metal standard. The two must be detailed as a coordinated pair so water shed by the coping lands on, not behind, the through-wall flashing. (11.10.2)

NOTE The flashing must be installed in the correct sequence relative to the backup, WRB, and cavity media, because each layer is concealed by the next. (12.2)

NOTE Flashing damaged during the masonry work above it is concealed before it can be repaired, so it must be protected as installed. (12.4)

NOTE Retrofitting flashing into existing masonry is constrained by the existing wall and is a distinct condition from new construction. (12.6)

NOTE In rehabilitation work where existing flashing has failed or is absent, the replacement flashing extent, the saw-cut or rebuild method, and the weep and drainage provisions shall be detailed for the specific existing assembly rehabilitation flashing extent and method. (12.6.1)

NOTE Cut-and-insert reglet flashing, full course rebuild, and surface-mounted termination are all valid retrofit strategies; the choice depends on what the existing wall allows and shall be detailed rather than left to the field. (12.6.2)

NOTE The purpose of all the foregoing detail is a wall that drains; where the stakes justify it, that performance should be confirmed by test rather than assumed. (13.2)

NOTE Where a water test is specified, the assembly shall be tested by an ASTM E514-adapted driving-rain load and shall demonstrate discharge at the weeps with no water reaching the interior face of the backup. (13.2.1)

NOTE ASTM E514 is a laboratory chamber method; a field-adapted application of its driving-rain load to a mock-up or to a production wall area is the practical acceptance test. The test confirms the drainage path works as a system, not merely that individual components were installed. (13.2.2)

NOTE Membrane flashings in particular are degraded by ultraviolet exposure and heat before they are even installed. (14.2)

NOTE Proprietary flashing and cavity-drainage products carry manufacturer warranties that the closeout submittals must capture for the owner. (15.2)

NOTE Because flashing is concealed, the only practical spare-parts provision is materials for future tie-in or repair at penetrations made after construction. (16.2)