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Safety Cue
Task-specific safety guidance for ordinary flashing and cutting hazards.
Chapter 13
Install Weep Holes, Flashing, and Masonry Drainage Details
Install and inspect one complete masonry water-management mockup at a base, opening, or shelf-angle condition, with continuous flashing, correctly formed end dams, an open drainage cavity, and functioning weeps.
Field Cue System
These cues appear at the point of work. They identify safety, code, manufacturer, and measurement issues before they become concealed water-management failures.
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Critical Safety Cue
Serious injury, structural failure, or major water damage is possible.
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Field Safety Cue
Practical work-area safety: access, footing, lighting, and housekeeping.
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Code Alert
Local requirements vary. Verify permit, inspection, and jurisdictional rules.
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Manufacturer Cue
Follow product-specific instructions for flashing, tapes, primers, and weeps.
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Measurement Cue
Lap, slope, spacing, and clearance guidance.
Job Overview
This chapter qualifies you to install and inspect one complete masonry drainage mockup: the flashing, end dams, cavity drainage material, and weep system that carry incidental moisture out of a masonry wall before it can reach the structure. The finished work product is one documented base, opening, or shelf-angle drainage mockup with continuous flashing, formed end dams, an open cavity, and functioning weeps, verified against the approved wall section.
This chapter treats flashing and weeps as a single connected system, not as separate accessories. A flashing lap that reverses direction, an end dam that is missing, a cavity bridged with mortar droppings, or a weep spaced incorrectly all defeat the same drainage path. You will mark every flashing and weep location from the approved wall section, install compatible materials in the correct lap sequence, form end dams at every termination, keep the cavity open, and install weeps aligned with the flashing before any veneer or wall work conceals these details.
This is the thirteenth chapter in the book. It depends on the readiness plan from Chapter 1, the controlled work area from Chapter 2, and the wall layout from Chapter 4, and it supplies the flashing and weep details that Chapter 11 and Chapter 12 install veneer around and that the Chapter 20 capstone must reproduce in full.
Skills You Will Demonstrate
- RM-073 — Identify flashing locations, marking every base, through-wall, head, sill, lintel, and shelf-angle location and every weep on the approved wall section before work begins.
- RM-074 — Install base flashing, including the required back leg, outward slope, WRB integration, and end dams.
- RM-075 — Install through-wall flashing above lintels, openings, shelf angles, and interruptions, maintaining laps and end dams.
- RM-076 — Form weep holes at the specified spacing, aligned with flashing and kept free of mortar and sealant.
- RM-077 — Maintain the drainage cavity, keeping it free of mortar bridging and mortar-dropping obstruction.
- RM-078 — Inspect water-management details, verifying laps, adhesion, end dams, slope, outlets, cavity condition, and weeps before concealment.
Where This Skill Fits
Every veneer, cavity wall, and shelf-angle transition in this book depends on the flashing and weep system built here. Chapter 11 installs brick veneer directly on top of the base flashing and weeps this chapter forms, and Chapter 12 relies on the same water-management logic when the veneer type is stone. The photograph-before-concealment discipline you practice here — documenting laps, end dams, and weeps before veneer covers them — is the same discipline the Chapter 20 capstone inspection requires at final acceptance.
The stop-work judgment you use here — refusing to seal a reversed lap, a missing end dam, or a blocked weep with sealant rather than correcting the detail — carries into every later chapter that touches moisture management, including Chapter 15 crack repair and Chapter 19 cleaning and sealing.
Scope and Intended Use
This chapter covers:
- reviewing the approved wall section to identify every water-entry and drainage point
- selecting compatible flashing, tapes, primers, end-dam material, drip edge, and sealants
- preparing the substrate and integrating flashing with the WRB in shingle-lap sequence
- installing base flashing with the required back leg and outward slope
- forming end dams at every flashing termination
- installing through-wall flashing above lintels, openings, shelf angles, and interruptions
- installing cavity drainage material or mortar-dropping control and keeping the cavity open
- installing weeps at the specified spacing, aligned with flashing
- installing termination or counterflashing where specified
- performing a limited drainage observation or mockup test where approved
- inspecting and photographing every concealed detail before veneer or wall work proceeds
This chapter does not authorize the learner to:
- invent flashing dimensions, lap lengths, weep spacing, cavity widths, or end-dam geometry not supplied by the approved wall section, adopted code, or manufacturer instructions
- install veneer, brick, block, or stone units over an unapproved or unverified flashing and weep system; unit installation belongs to Chapter 11 and Chapter 12
- seal pinholes, reverse laps, blocked outlets, or incompatible materials with sealant as a substitute for correcting the detail
- proceed past a flashing or weep deficiency without correction and reinspection before concealment
Any flashing, end-dam, cavity, or weep condition that fails the inspection in this chapter must be corrected and reinspected before veneer or wall work conceals it.
Reference Conventions
Establish these references before any flashing or weep is installed, and use them consistently across the mockup.
| Term | Definition |
|---|---|
| Back leg | The vertical portion of base flashing that turns up behind the WRB or backup wall to prevent water from tracking behind the flashing |
| End dam | A formed or applied upturn at the end of a flashing run that prevents water from flowing off the end of the flashing into the wall |
| Shingle lap | The overlap sequence in which each higher flashing or WRB course overlaps the course below it, so water always sheds outward and downward |
| Drainage cavity | The open air space behind veneer or cladding that carries incidental moisture down to the flashing and out through the weeps |
| Weep | An opening in the mortar joint or flashing system, at the specified spacing, that allows drainage water to exit the cavity above the flashing |
Project Identification Record
Before beginning installation, record the selected mockup and its controlling documents on the Flashing and Weep Inspection Log:
Mockup location: ______ (base / opening / shelf-angle) Wall section reference: ____________
Flashing material and manufacturer: ____________ Weep type and spacing per drawing: ____________
Date installed: ____________ Installer name: ____________
Prerequisites
- A completed Chapter 1 readiness plan and a passed base or support inspection for the location where the mockup will be installed
- An approved wall section identifying every flashing, end-dam, cavity, and weep location and dimension for the selected mockup
- A clean, continuous WRB or substrate at the mockup location, free of unresolved damage or open penetrations
- Compatible flashing, tapes, primers, end-dam material, drip edge, weeps, and sealants staged and verified against manufacturer instructions
- Confirmation that ambient and surface temperatures are within the range required by the flashing and tape manufacturer
Common Field Fundamentals
Every flashing and weep detail in this book, from a single base condition to the full Chapter 20 capstone, depends on the same sequence taught here: identify every water-entry point, select compatible materials, integrate flashing with the WRB in shingle-lap order, form end dams, keep the cavity open, install weeps aligned with the flashing, and inspect the complete system before it is concealed.
IdentificationEvery flashing and weep location marked from the approved wall section
SubstrateClean, continuous WRB with damage repaired before flashing begins
Base flashingBack leg, outward slope, and shingle-lap integration with the WRB
End damsFormed at every flashing termination to prevent end-run water loss
Through-wall flashingAbove lintels, openings, shelf angles, and interruptions
CavityOpen, unbridged, and protected from mortar droppings
WeepsInstalled at specified spacing, aligned with flashing, never filled
InspectionLaps, adhesion, end dams, slope, outlets, cavity, and weeps verified and photographed
Flashing as a Single Connected System
Treat every flashing run in this chapter as one connected water-management system rather than a series of separate patches. A back leg without a matching end dam, an end dam without a matching weep, or a weep installed above rather than at the flashing elevation each defeats the system at the point of the missing connection. Verify the full path from entry point to exterior outlet before installing the next component.
RM-073 – RM-078
Installation / Water Management / Inspection
Masonry Flashing and Weep Drainage Mockup
A. Finished-Project Specification
Deliverable: one complete base, opening, or shelf-angle drainage mockup consisting of substrate preparation, base or through-wall flashing with back leg and shingle-lap WRB integration, formed end dams at every termination, cavity drainage material or mortar-dropping control, weeps installed at the specified spacing and aligned with the flashing, termination or counterflashing where specified, and a documented inspection of every detail before concealment.
B. Component Schedule
| Component | Quantity | Material | Location / Detail | Preparation |
|---|---|---|---|---|
| Base flashing | Per mockup length, as specified in the wall section | Approved flashing membrane or metal as specified | Base of wall or cavity | Cut to length with back leg and outward slope per drawing |
| Through-wall flashing | Per opening, lintel, or shelf-angle location specified | Approved flashing membrane or metal as specified | Above lintels, openings, shelf angles, interruptions | Cut to length with required laps |
| End dams | One per flashing termination | Formed flashing material or compatible end-dam accessory | Every flashing end and termination | Formed or applied per manufacturer instructions |
| Cavity drainage material | Per cavity area specified | Mortar-dropping control or drainage mat as specified | Full cavity height above flashing | Cut and fastened per manufacturer instructions |
| Weeps | Per spacing specified in the wall section | Open-head weeps, tubes, wicks, or proprietary weep accessories as specified | Aligned with flashing at specified spacing | Installed without mortar or sealant obstruction |
C. Material Takeoff
- Flashing membrane or metal stock in the type, gauge or thickness, and width specified by the approved wall section, sufficient for the full mockup length plus laps
- Compatible tapes and primers matched to the flashing product and substrate
- End-dam material or accessories sufficient for every flashing termination
- Cavity drainage material or mortar-dropping control sized to the specified cavity height and width
- Weep accessories in the type and quantity matching the specified spacing over the mockup length
- Compatible sealant limited to the specific locations identified by manufacturer instructions; sealant is not a substitute for a missing flashing or end dam
D. Reference Conventions
Use the terms defined in the Reference Conventions table above. Additionally: the exterior face of flashing is the surface exposed to the cavity or exterior air; the interior leg is the portion integrated with the WRB or backup wall; upslope and downslope refer to the direction of water flow along the flashing as installed.
E. Acceptance Standards
| Check | Standard |
|---|---|
| Back leg and slope | Back leg height and outward slope match the approved wall section; verified with a level before cavity material is installed |
| Shingle lap | Every lap overlaps the course below it in the direction of water flow; no reverse lap present at any transition |
| End dams | Formed or applied at every flashing termination; no gap through which water could bypass the end of the flashing |
| Cavity condition | Open from top to weep elevation; free of mortar bridging, droppings, or obstruction of the drainage material |
| Weep spacing and alignment | Weeps installed at the spacing specified in the wall section and aligned with the flashing elevation; no weep filled with mortar or sealant |
| Sealant use | Limited to locations identified by manufacturer instructions; never used to correct a missing flashing, end dam, or blocked weep |
| Photographic record | Every flashing lap, end dam, cavity condition, and weep location photographed before concealment by veneer or wall work |
F. Layout and Substrate Preparation
- Review the approved wall section and identify every water-entry and drainage point. Mark base flashing, through-wall flashing, head flashing, sill flashing, lintel flashing, shelf-angle flashing, end dams, and weeps directly on the mockup or a site sketch.
- Mark base flashing, through-wall flashing, head flashing, sill flashing, lintel flashing, shelf-angle flashing, end dams, and weeps. Record each location and dimension on the Flashing and Weep Inspection Log before cutting any material.
- Confirm substrate and WRB are clean and continuous. Repair any WRB damage using the approved building-envelope method before flashing begins.
- Select compatible flashing, tapes, primers, end-dam material, drip edge, and sealants. Verify every product against the approved wall section and manufacturer literature.
- Verify corrosion and material compatibility. Confirm flashing metal, fasteners, and adjacent materials will not create a galvanic or chemical incompatibility.
- Prepare the substrate within product limits. Confirm surface temperature, moisture condition, and cleanliness meet the flashing and tape manufacturer's application requirements.
G. Base and Through-Wall Flashing Installation
- Install base flashing with the required back leg and outward slope. Verify slope with a level before proceeding to the next step.
- Integrate the flashing with the WRB in shingle-lap order. Confirm each lap directs water outward and downward with no reverse condition.
- Form end dams at terminations. Form or apply an end dam at every flashing end so no gap allows water to bypass the termination.
- Extend flashing to the exterior face or drip as specified. Confirm the flashing extends beyond the wall face by the dimension in the approved wall section.
- Install through-wall flashing above lintels, openings, shelf angles, and interruptions. Repeat the back-leg, slope, lap, and end-dam requirements at each location.
- Seal penetrations only with compatible accessories. Use manufacturer-specified boots, collars, or patches for any penetration; do not rely on sealant alone.
H. Cavity and Weep Installation
- Install cavity drainage material or mortar-dropping control. Fasten per manufacturer instructions and confirm full coverage of the specified cavity height.
- Keep the cavity open and free of mortar bridging. Inspect for droppings or debris and remove any obstruction before installing the next component.
- Install open-head weeps, tubes, wicks, vents, or proprietary weeps at specified spacing. Measure and mark each location before installation.
- Keep weeps aligned with flashing. Confirm each weep sits at the flashing elevation, not above or below it.
- Do not fill weeps with mortar or sealant. Inspect each weep after installation to confirm it remains open.
- Install termination or counterflashing where specified. Confirm the termination detail matches the approved wall section.
I. Verification and Inspection
- Perform a limited drainage observation or mockup test where approved. Follow the specific test method, water volume, and duration identified in the approved wall section; do not perform an unapproved or improvised water test.
- Inspect laps, adhesion, end dams, slope, outlet, cavity, weeps, and penetrations. Record each item as Pass or Deficient on the Flashing and Weep Inspection Log.
- Photograph concealed details. Photograph every flashing lap, end dam, cavity condition, and weep location with a tape measure in frame showing the as-built dimension.
- Correct pinholes, reverse laps, blocked outlets, and incompatible materials before veneer work. Reinspect every corrected item and record the reinspection result before the mockup is released to Chapter 11 or Chapter 12 veneer work.
Common Readiness Inspection
Inspect every flashing and weep mockup using the same checks regardless of the selected location.
- Lap and slope check: confirm every flashing lap sheds water outward and downward and that base flashing slope was verified with a level before concealment.
- End-dam check: confirm an end dam is present and effective at every flashing termination.
- Cavity check: confirm the drainage cavity is open from top to weep elevation with no mortar bridging or debris.
- Weep check: confirm weeps are installed at the specified spacing, aligned with the flashing, and free of mortar or sealant obstruction.
- Documentation check: confirm every concealed detail was photographed with a measurement reference before veneer or wall work proceeded.
Complete the Flashing and Weep Inspection Log in the Inspection Checklist section below before releasing the mockup to veneer work.
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Failure Points and Troubleshooting
Cleanup
This chapter ends with a documented, verified drainage mockup, not a visually finished wall with unverified details underneath.
- Confirm every photograph is labeled with the component, location, and date it documents
- File the completed Flashing and Weep Inspection Log with the approved wall section it references
- Dispose of flashing offcuts and packaging without leaving sharp metal edges in the work area
- Clean and store cutting and forming tools
- Retain the inspection log and photographs for use in Chapter 11, Chapter 12, and the Chapter 20 capstone
Field Terms
- Back Leg
- The vertical portion of base flashing that turns up behind the WRB or backup wall.
- End Dam
- A formed or applied upturn at a flashing termination that prevents water from bypassing the end of the run.
- Shingle Lap
- An overlap sequence in which each higher course of flashing or WRB overlaps the course below it.
- Drainage Cavity
- The open air space behind veneer or cladding that carries moisture down to the flashing and out through the weeps.
- Weep
- An opening in a mortar joint or flashing system that allows drainage water to exit a masonry cavity.
- Mortar-Dropping Control
- A material installed in the cavity to prevent mortar droppings from bridging or blocking the drainage path.
- Through-Wall Flashing
- Flashing installed above lintels, openings, shelf angles, or other interruptions in a masonry wall.
- Counterflashing
- A termination flashing installed to cover and protect the top edge of another flashing component.
- Flashing and Weep Inspection Log
- The document recording every flashing, end-dam, cavity, and weep finding, correction, and photographic reference.
Skill Check
- Why must every flashing and weep location be marked from the approved wall section before installation begins, rather than positioned by general trade practice?
- What is the difference between a correctly shingle-lapped flashing joint and a reverse lap, and why does a reverse lap defeat the drainage system?
- Why is an end dam required at every flashing termination, and what failure occurs when one is omitted?
- Why must weeps never be filled with mortar or sealant, even when doing so would improve the wall's appearance?
- What must the installer do, and not do, when mortar droppings are found bridging the drainage cavity?
- Why must every flashing, end-dam, cavity, and weep detail be photographed before veneer or wall work conceals it?
- What is the correct response when a concealed detail cannot be verified because it was covered before inspection?
- Why is sealant not an acceptable substitute for a missing flashing, end dam, or blocked weep?
- What conditions require a limited drainage observation or mockup test, and what must the test method be based on?
- How does the flashing and weep system installed in this chapter connect to the veneer work performed in Chapter 11 and Chapter 12?
Competency Rubric
| Competency | Independent Pass Standard | Not Demonstrated | With Assistance | Independently |
|---|---|---|---|---|
| RM-073 | Correctly identifies and marks every flashing and weep location from the approved wall section before installation begins | |||
| RM-074 | Installs base flashing with the required back leg, outward slope, WRB integration, and end dams, verified with a level | |||
| RM-075 | Installs through-wall flashing above lintels, openings, shelf angles, and interruptions with correct laps and end dams | |||
| RM-076 | Forms weep holes at the specified spacing, aligned with flashing, and free of mortar or sealant obstruction | |||
| RM-077 | Maintains the drainage cavity free of mortar bridging and mortar-dropping obstruction throughout installation | |||
| RM-078 | Inspects and photographs laps, adhesion, end dams, slope, outlets, cavity condition, and weeps before concealment |
Mark one column per competency. Only Demonstrated Independently awards the competency; Demonstrated with Assistance authorizes additional supervised practice but does not complete the requirement.
Inspection Checklist — Flashing and Weep Inspection Log
| Item | Finding | Pass / Deficient | Correction | Reinspected (Date) |
|---|---|---|---|---|
| Base flashing back leg and slope | ||||
| Shingle lap sequence | ||||
| End dams | ||||
| Through-wall flashing | ||||
| Cavity drainage material and condition | ||||
| Weep spacing and alignment | ||||
| Termination or counterflashing | ||||
| Photographic record complete |
Drainage observation performed: ______ (Y/N) Result: ____________
Released to veneer work: ______ (Y/N) Date: ____________ Inspector name: ____________
Performance Check
With installation complete, review the Flashing and Weep Inspection Log against the Acceptance Standards table and confirm every lap, end dam, cavity condition, and weep has been recorded with a measurement and photograph. Confirm every Deficient item has a documented correction and reinspection record before the mockup is released to veneer work. A mockup with any unresolved reverse lap, missing end dam, blocked weep, or bridged cavity must not be concealed until the deficiency is corrected and reinspected.
Project Closeout
You have completed the thirteenth chapter in the residential masonry sequence: installing weep holes, flashing, and masonry drainage details. This chapter required you to identify flashing locations (RM-073), install base flashing (RM-074), install through-wall flashing (RM-075), form weep holes (RM-076), maintain the drainage cavity (RM-077), and inspect water-management details (RM-078).
You now have a documented masonry drainage mockup with continuous flashing, formed end dams, an open cavity, and functioning weeps, verified and photographed before concealment. This mockup, and the inspection log describing it, carries directly into the next chapters: the brick and stone veneer installations in Chapter 11 and Chapter 12 depend on the exact flashing and weep system you built and verified here.
File your completed Flashing and Weep Inspection Log and photographs with the approved wall section for this project. You will reference this exact drainage system throughout the rest of this book.