+---
+title: Through-Wall Flashing and Masonry Moisture Control
+category: Building Envelope
+toc_depth: 3
+description: >
+ When to use: Design and installation of drainage-plane through-wall flashings
+ built into masonry veneer, brick cavity walls, CMU backup, and mixed-cladding
+ assemblies to intercept water that penetrates the outer wythe and redirect it
+ to the exterior, with the paired weep/vent and cavity-drainage systems. Covers
+ base-of-wall, lintel/shelf-angle, sill, head, and parapet conditions in new
+ commercial, institutional, and multi-family construction and in masonry
+ rehabilitation where existing flashing has failed or is absent.
+ Not intended for: Roofing edge metal, copings, and roof-to-wall terminations
+ (use [[sync/sheet-metal-flashing-and-trim]]); air/water-resistive barrier
+ membrane specification and continuity (use [[sync/air-barriers]] — this
+ standard coordinates with, never substitutes for, the WRB); veneer ties,
+ anchors, and shelf-angle design (use [[sync/masonry-anchorage-and-veneer]]);
+ below-grade or under-slab self-adhered sheet waterproofing (use
+ [[sync/self-adhering-sheet-waterproofing]]); sheathing and its WRB facing (use
+ [[sync/wood-sheathing]]); and window/door sill-pan flashing as a fenestration
+ sub-component (see ASTM E2112 / AAMA 711).
+---
+
+# Scope {toc}
+
+## This standard governs through-wall flashing and the paired drainage components that together form the moisture-control system of a drained masonry wall.
+
+## 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. {note}
+
+## The following work is included in this standard.
+
+## The included scope is enumerated so the Contractor and Engineer can confirm one section owns each component of the drainage path. {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. {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. {note}
+
+## The following work is excluded and is governed by other standards.
+
+## Exclusions are stated as boundaries, not obligations, so that responsibility is unambiguous where this standard meets adjacent trades. {note}
+
+### Roofing edge metal, coping counterflashing, and roof-to-wall terminations are excluded and are governed by [[sync/sheet-metal-flashing-and-trim]]. {note}
+
+### Air/water-resistive barrier membrane products and continuity are excluded and are governed by [[sync/air-barriers]]; this standard coordinates with the WRB but does not specify it. {note}
+
+### Masonry veneer ties, anchors, and shelf-angle structural design are excluded and are governed by [[sync/masonry-anchorage-and-veneer]]. {note}
+
+### Below-grade and under-slab self-adhered sheet waterproofing is excluded and is governed by [[sync/self-adhering-sheet-waterproofing]]. {note}
+
+### Wall sheathing and its housewrap/WRB facing are excluded and are governed by [[sync/wood-sheathing]]. {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. {note}
+
+## The boundary between this standard and [[sync/sheet-metal-flashing-and-trim]] is the function of the metal. {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. {note}
+
+# Referenced Standards {toc}
+
+## Materials, design, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited or a more recent edition is enforced by the authority having jurisdiction.
+
+## 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. {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. {note}
+
+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| TMS 402/602-22 | Building Code Requirements and Specification for Masonry Structures |
+| IBC 2024 Chapter 21 | International Building Code — Masonry (Section 2104 flashing provisions) |
+| ASTM E514/E514M-20 | Water Penetration and Leakage Through Masonry |
+| ASTM E2112-19 | Installation of Exterior Windows, Doors and Skylights |
+| AAMA 711-22 | Self-Adhering Flashing Used for Installation of Exterior Wall Fenestration Products |
+| ASTM C1329 | Mortar Cement |
+| ASTM D1970/D1970M-17 | Self-Adhering Polymer Modified Bituminous Sheet Materials (steep-roof underlayment; material-property reference for SBS flashing) |
+| ASTM D4637/D4637M-15 | ASTM Type I and II Unreinforced and Reinforced EPDM Geomembranes |
+| SMACNA Architectural Sheet Metal Manual, 8th Ed. | Fabrication of metal through-wall flashing: gauges, drip profiles, seams, end dams |
+
+# Submittals {toc}
+
+## Action Submittals
+
+## 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. {note}
+
+### The Contractor shall submit the following action submittals for review before fabrication and installation:
+- Product data for each flashing material, weep device, vent, cavity drainage medium, lap sealant or splice tape, and termination bar, with manufacturer material and thickness designations.
+- Manufacturer compatibility statements confirming the flashing, lap sealant, WRB membrane, and adjacent mortar are mutually compatible.
+- Shop drawings of fabricated metal flashing showing drip-edge profile, end-dam height and construction, splice details, and corner and transition pieces.
+- Large-scale flashing details at base of wall, lintel/shelf angle, sill, head, parapet, and each abutment, showing the turned-up leg, the lap with the WRB, weep type and spacing, and cavity drainage medium.
+- Sample of each flashing material and one fabricated end dam and corner.
+
+```datasheet
+label: Action submittals required
+type: checkbox
+options:
+ - Product data (flashing, weeps, vents, drainage media, sealant/tape, termination bar)
+ - Manufacturer compatibility statements (flashing / sealant / WRB / mortar)
+ - Shop drawings of fabricated metal flashing (drip, end dam, splices, corners)
+ - Large-scale flashing details at each wall condition
+ - Material samples and fabricated end-dam/corner sample
+default:
+ - Product data (flashing, weeps, vents, drainage media, sealant/tape, termination bar)
+ - Manufacturer compatibility statements (flashing / sealant / WRB / mortar)
+ - Large-scale flashing details at each wall condition
+```
+
+## Informational Submittals
+
+## Informational submittals support quality assurance but do not, by themselves, gate fabrication. {note}
+
+### The Contractor shall submit the following informational submittals:
+- Installer qualification records demonstrating experience with drained masonry flashing of comparable scope.
+- Mock-up construction and water-test records when a mock-up or field water test is required by the Contract Documents.
+- Field reports for each inspection hold point at flashing courses.
+
+```datasheet
+label: Informational submittals required
+type: checkbox
+options:
+ - Installer qualifications
+ - Mock-up and water-test records
+ - Inspection hold-point field reports
+default:
+ - Installer qualifications
+ - Inspection hold-point field reports
+```
+
+## Closeout Submittals
+
+## Closeout submittals document the as-built drainage system for the building owner's future maintenance and any warranty claim. {note}
+
+### The Contractor shall submit the following closeout submittals:
+- Warranty documents for proprietary flashing and cavity-drainage products.
+- Record drawings noting any field-modified flashing details and the as-built weep spacing.
+
+```datasheet
+label: Closeout submittals required
+type: checkbox
+options:
+ - Product warranties
+ - Record drawings of as-built flashing and weep spacing
+default:
+ - Product warranties
+ - Record drawings of as-built flashing and weep spacing
+```
+
+# Quality Assurance {toc}
+
+## Installer Qualifications
+
+## Concealed flashing cannot be repaired without demolishing the wall, so installer competence is the primary defense against latent leakage. {note}
+
+### The flashing installer shall be a masonry contractor with documented experience installing drained-cavity through-wall flashing on at least three comparable projects.
+
+### The Contractor shall designate a single party responsible for the continuity of the drainage plane where the flashing laps the WRB, even when the two are installed by different trades.
+
+## Mock-Up
+
+## A mock-up resolves material-compatibility and lap-sequence questions before they are buried in the production wall. {note}
+
+### When required by the Contract Documents, the Contractor shall construct a wall mock-up incorporating each flashing condition, weep type, and the WRB lap, and shall not begin production work until the mock-up is accepted.
+
+### The accepted mock-up shall remain available for reference until the flashing work is complete and shall establish the standard of workmanship for laps, end dams, and weep installation.
+
+## Field Water Test
+
+## 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. {note}
+
+### When a field water test is specified, the test wall shall be subjected to a simulated driving-rain load of 5 lb/hr per ft² (24 kg/hr per m²) over the test area for a minimum of 4 hours, with water observed discharging at the weeps and no water reaching the interior face of the backup.
+
+```datasheet
+label: Field acceptance method
+type: radio
+options:
+ - Visual inspection at flashing hold points only
+ - Visual inspection plus mock-up water test
+ - Visual inspection plus field water test on production wall (ASTM E514-adapted)
+default: Visual inspection plus mock-up water test
+```
+
+## Inspection Hold Points
+
+## Because flashing is concealed course by course, inspection must occur while each flashing run is still exposed. {note}
+
+### Installation of masonry above a flashing course shall not proceed until the flashing, its laps, end dams, weeps, and cavity drainage medium at that course have been inspected and accepted.
+
+# Environmental and Service Conditions {toc}
+
+## Exposure
+
+## Flashing material selection follows from the severity of wetting and thermal exposure at each location. {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. {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. {note}
+
+```datasheet
+label: Exposure severity (governs material and thickness selection)
+type: radio
+options:
+ - Standard exposure (sheltered, low driving-rain index)
+ - Moderate exposure (typical commercial facade)
+ - Severe exposure (coastal, high-rise, or high driving-rain index)
+default: Moderate exposure (typical commercial facade)
+```
+
+## Cavity Width
+
+## A drainage cavity that is too narrow bridges with mortar and stops draining; minimum clear width is a code requirement, not a preference. {note}
+
+### The clear drainage cavity behind the veneer shall be a minimum of 2 in. (50 mm) per TMS 402 to maintain a drainage path.
+
+### A clear cavity of 2-1/2 to 3 in. (64 to 75 mm) should be provided for brick-veneer-over-CMU assemblies to tolerate mortar droppings and construction variation.
+
+```datasheet
+label: Clear cavity width
+type: range
+unit: in
+min: 2
+max: 4.5
+step: 0.5
+default: 2.5
+```
+
+# Flashing Materials {toc}
+
+## Material Selection
+
+## The four material families each carry a different cost, durability, and compatibility profile; the choice drives nearly every downstream detail. {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. {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. {note}
+
+### Aluminum shall not be used as masonry flashing in contact with mortar. {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. {note}
+
+```datasheet
+label: Flashing material family
+type: radio
+options:
+ - Sheet copper
+ - Stainless steel (Type 316L)
+ - Galvanized steel
+ - EPDM membrane
+ - Rubberized-asphalt (SBS) self-adhered membrane
+ - Composite metal-laminate membrane
+default: Rubberized-asphalt (SBS) self-adhered membrane
+```
+
+## Sheet-Metal Flashing
+
+## Metal thickness governs the flashing's resistance to puncture during construction and to long-term fatigue at the drip. {note}
+
+### Sheet copper flashing shall be a minimum of 10 oz/sf (0.0135 in.) per SMACNA; 16 oz/sf (0.0216 in.) should be used where the flashing is fabricated with an integral drip edge or at severe exposure.
+
+### Stainless-steel flashing shall be a minimum of 26-gauge Type 316L.
+
+### Galvanized-steel flashing shall be a minimum of 26-gauge, and 24-gauge should be used at severe exposures.
+
+### Sheet-metal flashing shall be fabricated with seams, end dams, and drip profiles per the SMACNA Architectural Sheet Metal Manual, 8th Ed.
+
+```datasheet
+label: Sheet-metal flashing thickness / gauge
+type: select
+options:
+ - Copper 10 oz/sf (0.0135 in.)
+ - Copper 16 oz/sf (0.0216 in.)
+ - Stainless steel 26 ga Type 316L
+ - Galvanized steel 26 ga
+ - Galvanized steel 24 ga
+default: Copper 10 oz/sf (0.0135 in.)
+```
+
+## EPDM Flashing
+
+## EPDM is a flexible, UV-tolerant membrane well suited to base-of-wall runs and irregular geometry. {note}
+
+### EPDM through-wall flashing shall be a minimum of 40-mil (1.0 mm) nominal thickness conforming to ASTM D4637.
+
+### EPDM flashing of 60-mil thickness should be used at base-of-wall conditions, where the membrane carries the full drainage load and is most exposed to construction abuse.
+
+```datasheet
+label: EPDM flashing thickness
+type: radio
+options:
+ - 40 mil (1.0 mm)
+ - 60 mil (1.5 mm)
+default: 60 mil (1.5 mm)
+```
+
+## Rubberized-Asphalt (SBS) Flashing
+
+## SBS self-adhered membrane bonds aggressively to the backup but is vulnerable to ultraviolet light and to incompatible sealants. {note}
+
+### Rubberized-asphalt flashing shall be a self-adhered SBS-modified membrane of 40 to 60 mil thickness, with low-temperature flexibility and lap-seal adhesion consistent with ASTM D1970.
+
+### Rubberized-asphalt flashing shall not be exposed at the face of masonry. {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. {note}
+
+### Rubberized-asphalt flashing shall be held back a minimum of 1/2 in. (13 mm) from the face of masonry, and 3/4 to 1 in. (19 to 25 mm) is preferred, to prevent staining.
+
+```datasheet
+label: Rubberized-asphalt setback from face of masonry
+type: range
+unit: in
+min: 0.5
+max: 1.5
+step: 0.25
+default: 0.75
+```
+
+## Material Compatibility
+
+## Most masonry flashing failures that are not installation errors are chemical-compatibility errors between the flashing and an adjacent material. {note}
+
+### The flashing material shall be confirmed compatible with the lap sealant or splice tape, the WRB membrane it laps, and the mortar it beds in, with manufacturer compatibility statements submitted before installation.
+
+### Solvent-based and coal-tar sealants shall not be used against rubberized-asphalt membrane, and bitumen-based products shall not be used against EPDM. {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. {note}
+
+### Dissimilar metals in contact shall be isolated with bituminous paint or polyethylene tape to prevent galvanic corrosion. {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. {note}
+
+# Flashing Geometry and Terminations {toc}
+
+## Drip Edge
+
+## 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. {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. {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. {note}
+
+### Membrane flashings shall be terminated at the face behind a separate metal drip edge or termination bar; the membrane shall not be the exposed drip.
+
+```datasheet
+label: Drip-edge projection beyond face of masonry
+type: range
+unit: in
+min: 0.25
+max: 0.75
+step: 0.125
+default: 0.375
+```
+
+```datasheet
+label: Flashing geometry at face
+type: radio
+options:
+ - Full through-wall flashing with integral metal drip edge
+ - Membrane flashing terminated behind separate metal drip edge
+ - Embedded leg with separate drip-edge termination bar
+default: Membrane flashing terminated behind separate metal drip edge
+```
+
+## Turned-Up Leg
+
+## 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. {note}
+
+### The flashing shall be turned up against the backup wall a minimum of 8 in. (200 mm) at base-of-wall conditions and a minimum of 6 in. (150 mm) at shelf angles and lintels.
+
+### The turned-up leg shall be mechanically terminated to the backup with a termination bar or be bonded to the WRB so that no free edge of flashing can admit water behind it.
+
+```datasheet
+label: Turned-up leg height
+type: select
+options:
+ - 6 in. (150 mm) at shelf angles / lintels
+ - 8 in. (200 mm) at base of wall
+ - 10 in. (250 mm) at severe exposure base of wall
+default: 8 in. (200 mm) at base of wall
+```
+
+## Slope to Drainage
+
+## Flat or back-sloped flashing holds water against the backup and feeds it into the wall instead of out the weeps. {note}
+
+### The flashing shall be installed sloping toward the weeps at a minimum of 1/8 in. per ft (1%); flat and back-sloped flashing is prohibited.
+
+## Laps
+
+## Field splices are where the most leaks occur because they receive less care than shop-fabricated lengths. {note}
+
+### Flashing splices shall lap a minimum of 6 in. (150 mm) and shall be sealed with a compatible lap sealant or manufacturer-supplied splice tape; dry, unsealed laps are prohibited.
+
+### Each field splice shall be a designated inspection hold point.
+
+```datasheet
+label: Minimum splice lap length
+type: range
+unit: in
+min: 6
+max: 12
+step: 1
+default: 6
+```
+
+## End Dams
+
+## End dams close the ends of a flashing run so that laterally draining water cannot run off the end and back into the wall. {note}
+
+### Every flashing run shall terminate in an end dam, and the turned-up end-dam leg shall be a minimum of 1 in. (25 mm) high; 1-1/2 in. (38 mm) should be provided as the standard default.
+
+### End dams shall be formed from the flashing material itself or from a compatible material, sealed watertight to the flashing and the backup.
+
+```datasheet
+label: End-dam height
+type: range
+unit: in
+min: 1
+max: 2
+step: 0.25
+default: 1.5
+```
+
+# Weep and Vent Systems {toc}
+
+## Weep Function
+
+## Weeps are the only exit for water that the flashing collects; their type and spacing determine whether the wall actually drains. {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. {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. {note}
+
+### Weep openings shall have a minimum inside diameter of 3/16 in. (4.8 mm) per TMS 602 Section 7.6.
+
+## Weep Type
+
+## The weep type trades off drainage capacity, insect resistance, and appearance. {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. {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. {note}
+
+```datasheet
+label: Weep type
+type: radio
+options:
+ - Open head joints
+ - Plastic weep-tube inserts
+ - Wire-loop weep vents
+ - Manufactured cellular / mesh weep vents
+default: Manufactured cellular / mesh weep vents
+```
+
+## Weep Spacing
+
+## Code sets a maximum spacing; the common project default is tighter to improve drainage and tolerance for blocked weeps. {note}
+
+### Weeps shall be spaced a maximum of 33 in. (838 mm) on center per TMS 602.
+
+### Weeps should be spaced at 24 in. (610 mm) on center, approximately one per brick module at every fourth head joint, to provide redundancy if individual weeps are blocked.
+
+```datasheet
+label: Weep spacing on center
+type: range
+unit: in
+min: 16
+max: 33
+step: 4
+default: 24
+```
+
+## Cavity Venting
+
+## Venting the top of the cavity in addition to weeping the base promotes airflow that helps dry the cavity between wetting events. {note}
+
+### Vents should be provided at the top of the drainage cavity and below shelf angles to promote cavity ventilation and drying, at a spacing matching the weeps below.
+
+```datasheet
+label: Provide cavity vents at top of cavity / below shelf angles
+type: radio
+options:
+ - "Yes — vents at top of cavity and below shelf angles"
+ - "No — weeps at base only"
+default: "Yes — vents at top of cavity and below shelf angles"
+```
+
+# Cavity Drainage and Mortar Control {toc}
+
+## Mortar Bridging
+
+## 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. {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. {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. {note}
+
+### The cavity drainage medium and its required location shall be shown on the wall sections and flashing details, not left to the field [[drawing: base-of-wall and shelf-angle flashing details]].
+
+```datasheet
+label: Cavity drainage medium
+type: radio
+options:
+ - Mortar-collection net (trapezoidal/dovetail mesh)
+ - Full-height cavity drainage mat
+ - Cavity drainage mesh strip above flashing
+default: Mortar-collection net (trapezoidal/dovetail mesh)
+```
+
+## Mortar at the Flashing Course
+
+## Excess mortar squeezed from the flashing bed joint can block weeps even when a drainage medium is present. {note}
+
+### Mortar at the flashing bed joint shall be kept lean and the bed kept free of squeeze-out that could obstruct weeps; raked or beveled mortar beds should be used at flashing courses.
+
+# Coordination with the Air/Water-Resistive Barrier {toc}
+
+## Continuity of the Drainage Plane
+
+## 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. {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. {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 [[sync/air-barriers]]. {note}
+
+### The lap between the flashing and the WRB shall be continuous and sealed.
+
+### Any reverse (water-trapping) lap between the flashing and the WRB is prohibited.
+
+```datasheet
+label: Flashing-to-WRB lap order
+type: radio
+options:
+ - Flashing laps over WRB leg (shingle, default)
+ - Per WRB manufacturer's tested transition detail
+default: Flashing laps over WRB leg (shingle, default)
+```
+
+# Flashing Locations {toc}
+
+## Base of Wall
+
+## The base-of-wall flashing is the most heavily loaded run in the wall and the one most often compromised by mortar fill. {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. {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. {note}
+
+### The base-of-wall flashing elevation and its relationship to grade, slab, or foundation shall be shown on the drawings [[drawing: base-of-wall flashing elevation]].
+
+## Lintels and Shelf Angles
+
+## Every horizontal structural interruption of the veneer is a new collection point that needs its own flashing, weeps, and end dams. {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. {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. {note}
+
+### Flashing at shelf angles shall not bridge the horizontal expansion joint below the angle in a way that prevents the joint from functioning.
+
+## Sills
+
+## Sill flashing protects the wall below window and other openings, where concentrated runoff from the opening above is common. {note}
+
+### Sill flashing shall be installed under masonry sills and at the base of openings, turned up at the back and at both ends to form a pan that drains outward, with end dams at each jamb.
+
+### Coordination of sill flashing with window and door sill-pan flashing shall be detailed so the fenestration pan drains onto, not behind, the masonry sill flashing, per ASTM E2112 and AAMA 711.
+
+## Heads
+
+## Head flashing intercepts water above an opening before it can enter the head of the frame below. {note}
+
+### Head flashing shall be installed over openings, lapped over the WRB and turned up against the backup, with end dams beyond each jamb and weeps in the course above.
+
+## Parapets
+
+## Parapets are exposed on two faces and are the wall condition most prone to flashing failure from thermal movement and freeze-thaw. {note}
+
+### Parapet through-wall flashing shall be installed below the coping bed and coordinated with the coping counterflashing, which is specified under [[sync/sheet-metal-flashing-and-trim]]. {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. {note}
+
+### Parapet flashing material shall be selected for the severe two-sided thermal and ultraviolet exposure of the parapet, favoring metal or composite flashing over bare SBS membrane.
+
+# Installation {toc}
+
+## Sequence
+
+## 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. {note}
+
+### The Contractor shall install the WRB and flashing in the sequence shown on the accepted details so that every lap is shingled to direct water outward and no flashing edge is left exposed behind the cladding.
+
+### Flashing shall be installed continuously with no unintentional gaps or breaks in the flashing run.
+
+### All corners, transitions, and changes in direction shall be formed from preformed or shop-fabricated pieces rather than field-cut butt joints wherever practical.
+
+## Protection During Construction
+
+## Flashing damaged during the masonry work above it is concealed before it can be repaired, so it must be protected as installed. {note}
+
+### Installed flashing shall be protected from puncture, displacement, and mortar fouling until the masonry above is laid, and any damaged flashing shall be replaced, not patched in place where the patch cannot be inspected.
+
+## Rehabilitation
+
+## Retrofitting flashing into existing masonry is constrained by the existing wall and is a distinct condition from new construction. {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 [[drawing: rehabilitation flashing extent and method]]. {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. {note}
+
+```datasheet
+label: Rehabilitation flashing strategy
+type: radio
+options:
+ - Full course rebuild with new through-wall flashing
+ - Cut-and-insert reglet flashing into existing bed joint
+ - Surface-mounted termination-bar flashing where rebuild is not feasible
+default: Full course rebuild with new through-wall flashing
+drawing_ref: rehabilitation flashing extent and method
+```
+
+# Testing {toc}
+
+## Water Penetration
+
+## 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. {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. {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. {note}
+
+### Failure of a water test shall require correction of the assembly and a repeat test before the affected work is concealed.
+
+# Delivery, Storage, and Handling {toc}
+
+## Storage
+
+## Membrane flashings in particular are degraded by ultraviolet exposure and heat before they are even installed. {note}
+
+### Flashing materials shall be delivered in the manufacturer's original packaging.
+
+### Flashing materials shall be stored off the ground and protected from ultraviolet exposure, heat, and physical damage.
+
+### Self-adhered membrane flashings shall be kept within the manufacturer's recommended temperature range until installed.
+
+### Sheet-metal flashing shall be stored flat or coiled to prevent permanent kinks and shall be handled to avoid scratching protective finishes.
+
+# Warranty {toc}
+
+## Product Warranty
+
+## Proprietary flashing and cavity-drainage products carry manufacturer warranties that the closeout submittals must capture for the owner. {note}
+
+### The Contractor shall provide the manufacturer's standard material warranty for each proprietary flashing and cavity-drainage product, and shall warrant the installation against defects in workmanship for the period required by the Contract Documents.
+
+```datasheet
+label: Installation workmanship warranty period
+type: range
+unit: yr
+min: 1
+max: 5
+step: 1
+default: 2
+```
+
+# Spare Parts {toc}
+
+## Attic Stock
+
+## Because flashing is concealed, the only practical spare-parts provision is materials for future tie-in or repair at penetrations made after construction. {note}
+
+### When required by the Contract Documents, the Contractor shall deliver attic stock of each flashing material, weep device, and lap sealant or splice tape sufficient for future penetrations and minor repair, in the quantities specified.
+
+```datasheet
+label: Attic stock to be delivered
+type: checkbox
+options:
+ - Flashing material (each type used)
+ - Weep devices / vents
+ - Lap sealant or splice tape
+ - Cavity drainage medium
+default:
+ - Flashing material (each type used)
+ - Lap sealant or splice tape
+```