Inspect Curtain Wall Drainage Paths and Weep Hole Continuity

Definition: Inspect curtain wall drainage paths and weep hole continuity for facade QA teams, ensuring unobstructed water egress, pressure-equalized cavities, and reliable moisture management across sills, stack joints, and mullion drainage networks.

Verify clear drainage channels, aligned baffles, and unobstructed weep exits.
Reduce leakage risk, staining, and hidden corrosion through proactive inspection.
Use probes, borescope, dyed-water checks, and calibrated spray testing.
Interactive, commentable checklist with export and QR code authentication.

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Checklist

Inspect curtain wall drainage paths and weep hole continuity to ensure water leaves the facade quickly and predictably. This checklist focuses on rainscreen drainage, weep slots, sill flashings, and pressure-equalized facade cavities without expanding into unrelated glazing performance or structural topics. By validating drainage continuity—from internal channels to exterior weeps—you prevent ponding, capillary backflow, efflorescence, and concealed corrosion. The process uses practical tools such as feeler wires, borescopes, dyed water, manometers, and controlled spray, while capturing photos, readings, and lot numbers for traceable quality assurance. Acceptance cues include minimum weep sizes, consistent slopes, aligned baffles, intact screens, and measured airflow that indicates a functioning cavity. When issues arise (e.g., sealant bridging, thermal packers blocking slots, or paint overspray), targeted corrections and re-tests confirm restored performance. Use this interactive checklist to assign actions, add comments, and verify closure, then export your records as PDF/Excel with a QR code for secure sign-off.

This checklist validates continuous drainage from sill pans and mullion channels to exterior weeps, reducing leakage, staining, and corrosion by verifying slopes, baffles, weep size, and airflow paths with documented evidence.
Practical field methods combine non-destructive probing, borescope inspection, dyed-water tracing, and controlled spray to confirm that water egress is free-flowing and repeats predictably across representative bays and elevations.
Clear acceptance criteria guide decisions: minimum weep diameters and spacing, sill slope tolerances, airflow indications, and defect resolution with before/after evidence, material batch records, and responsible sign-offs.
Interactive online checklist with tick, comment, and export features secured by QR code. Share actions with stakeholders, track re-tests, and archive a verified moisture-management record for turnover and future maintenance.

Preparation and Access

1. Review approved shop drawings and drainage diagrams; identify sill, stack-joint, and mullion drainage routes for each elevation. Mark inspection bays on a plan and attach annotated excerpts.
2. Confirm safe access to weep lines and sills using MEWP or swing stage; inspect tags, harnesses, and daily checks. Record access method, operator certification, and capture a setup photo.
3. Clean exterior surfaces around weeps with soft brush (no sealant disturbance) to expose slots. Photo before/after; bag and label any debris found for report attachment.

Drainage Pathways

4. Probe internal sill channels with a 2.5 mm nylon wire along full bay length; acceptance: continuous passage without hard obstruction. Note resistance points on drawing and photograph probe insertion.
5. Verify vertical stack-joint baffles align over sill drainage entries; acceptance: offset ≤ 3 mm. Use a borescope to capture alignment images at top, mid, and bottom of joint.
6. Check splice sleeves, seal dams, and thermal packers do not create unintended dams; maintain a 10 mm clear gap above dams for drainage continuity. Record close-up photos.

Weep Holes and Vents

7. Measure weep diameter with a drill-gauge card; acceptance: 6–10 mm. Confirm spacing 400–600 mm c/c or per approved project specifications and authority requirements. Record dimensions with scale in photo.
8. Confirm each sill end dam has at least one dedicated weep path; acceptance: visible outlet at each bay end. Document with end-on photographs and note elevation/bay ID.
9. Inspect insect/bug screens or covers; acceptance: intact mesh (≈1–2 mm), seated, and not clogged by paint or sealant. Capture macro photos showing clarity of openings.
10. Verify weep outlets sit ≥ 20 mm above adjacent surfaces or sealant beads to prevent ponding or blockage. Photograph with ruler or gauge showing clear stand-off.
11. Conduct dyed-water path check: introduce 250 mL colored water into interior drainage inlet; acceptance: discharge at corresponding exterior weep within 30 s. Record time-stamped video of inlet and outlet.

Flashings and Trays

12. Check sill pan or flashing slope outward using a digital level; acceptance: ≥ 1:15 (≈3.8°) with tolerance ±0.5°. Photograph the level reading and the sill reference.
13. Inspect internal upstands and corner joints for continuous sealant fillets; acceptance: no voids or gaps > 2 mm. Record close-ups and sealant batch/lot number labels.
14. Verify exterior perimeter sealant and backer rod do not bridge or cover weeps; acceptance: 25–40% backer compression, clear weep mouths. Photo with probe showing open mouth; record sealant cure date.
15. Confirm thermal breaks, packers, or shims maintain a 10 mm minimum clearance to drainage slots. Borescope cavities where covers obscure visibility and save still images.

Documentation and Testing

16. Induce light negative pressure (25–50 Pa) in the cavity zone using a portable fan; smoke-pencil near pressure vents should draw inward. Record manometer reading and video evidence.
17. Perform controlled hose spray at weep line: 5 min, 200–250 kPa, nozzle 300–500 mm standoff, avoid jetting into joints. Acceptance: water exits weeps, no interior leakage. Capture continuous video.
18. Use an endoscope to inspect 10% sample of bays for debris, sealant overrun, or misaligned baffles. Acceptance: clean pathways, components seated. Save geotagged images with bay IDs.
19. If blocked, clear weeps with nylon probe or compressed air ≤ 300 kPa; repeat dyed-water test to confirm restored flow. Record before/after photos and note corrective action responsible party.
20. Complete digital sign-off: attach photos, readings, batch numbers, and test videos; note any NCRs. Obtain superintendent and QA signatures; export PDF/Excel with embedded QR for record authentication.

Why Drainage Continuity Matters in Curtain Walls

Drainage continuity in curtain walls ensures that incidental water entering glazing rebates or pressure-equalized cavities exits through planned routes without wetting interior finishes or trapping moisture. Consistent pathways—from mullion channels through sill pans to exterior weeps—limit ponding, capillary action, and staining. When slopes are correct, baffles align, and weep sizes are adequate, small infiltrations dissipate safely. Breaks in continuity, however, cause hidden corrosion, swollen packers, freeze–thaw damage, and costly warranty claims. Field acceptance cues include clear weep outlets (typically 6–10 mm), outward sill slopes of at least 1:15, and unobstructed baffles visible on a borescope. A common jobsite issue is paint overspray or sealant bridging across weep mouths, which blocks discharge and forces water to track along unintended interfaces. Another is misaligned stack-joint baffles after cover installation. Methodical inspection and simple tracing tests confirm accurate flow, providing reliable moisture management without intrusive dismantling.

Target weeps 6–10 mm diameter and spaced 400–600 mm.
Sill flashings sloped outward ≥ 1:15 with ±0.5° tolerance.
Borescope confirms aligned baffles and clean channels.
Avoid sealant bridging or packers blocking drainage slots.

Field Methods to Verify Paths and Weeps

Non-destructive techniques make drainage verification efficient and repeatable. Start by mapping drainage routes on shop drawings, then probe channels with a nylon wire to detect obstructions. A compact borescope documents alignment at stack joints and under covers. Dyed-water tracing provides immediate confirmation of inlet-to-weep continuity; recorded transit times indicate restrictions. Where pressure moderation is designed, a light fan creates 25–50 Pa negative pressure and a smoke-pencil verifies airflow across vents, indicating an open cavity. A calibrated hose spray focuses on the weep zone to confirm discharge and check for unintended ingress without forcing water into joints. Throughout, capture clear, scaled photos, manometer readings, and videos to build an auditable trail. If issues surface—such as debris, sealant run-on, or packers in slots—correct locally and re-test the same way to prove resolution. These steps keep the process transparent and defensible.

Use dyed water to trace inlet-to-weep in under 30 s.
Record manometer Pa values during airflow checks.
Maintain hose pressure 200–250 kPa for 5 minutes.
Geotag images and videos for traceable evidence.

Typical Defects and Targeted Corrections

Frequent defects include clogged weep mouths from paint or sealant, misaligned stack-joint baffles, and thermal packers bridging drainage slots. Ponding on flat sills slows discharge and escalates leakage risk during wind-driven rain. Internal dams or splice details sometimes trap water when builders omit small relief gaps. Corrective actions are straightforward: clear obstructions with nylon probes or controlled air, trim packers to restore a 10 mm clearance, and re-seat baffles to align with sill entries. Add or reshape sealant fillets to remove voids and keep weep mouths open. Re-measure sill slopes, adjust shims as necessary, and repeat dyed-water and spray checks to confirm restored function. Document all before/after findings, material batch numbers, and who performed the fix. Consistent retesting and sign-off provide confidence that each corrected bay performs like the design intent.

Restore 10 mm clearance around drainage slots.
Realign baffles; acceptance offset ≤ 3 mm.
Rebuild sealant fillets; no gaps > 2 mm.
Repeat tests and capture before/after evidence.

How to Use This Interactive Curtain Wall Drainage Checklist

Preparation: Gather drawings, elevation keys, and the app on a tablet. Bring borescope, 2.5 mm probe, digital level, dyed water, hose with gauge, manometer, PPE, and safe access equipment.
Create project in the app: Input project, elevation, bay IDs, and assign roles. Upload relevant shop-drawing excerpts for quick reference during inspection.
Start interactive mode: Tick each item as you complete it, attach photos/videos/readings, and geotag observations. Use point-by-point acceptance notes to reduce ambiguity.
Collaborate: Add comments, tag responsible parties, and set due dates for corrective actions. Log retests with linked evidence to the original observation.
Export records: Generate a structured PDF/Excel pack with embedded media links. Include drawings, test parameters, and measurement logs for each elevation and bay.
Sign-Off: Capture digital signatures from the superintendent and QA. The export includes a QR code for document authentication and quick retrieval on site.

Inspect Curtain Wall Drainage Paths and Weep Hole Continuity

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Curtain Wall Drainage and Weep Continuity Inspection

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License: CC-BY 4.0. Please credit: “Curtain Wall Drainage and Weep Continuity Inspection by Quollnet” with a link to this source page.

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kamal tarek EcoArcKamal

Oct 11, 2026

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FAQ

Question: How often should we verify curtain wall weep continuity during construction?

Verify continuity at initial installation of each elevation, after any sequencing change, and following trades that can block openings (painting, sealants, cleaning). Sample at least 10% of bays or as project risk dictates, then increase frequency if failures appear. Always re-test after corrective actions and before handover.

Question: What simple field tests confirm drainage without dismantling covers?

Use a dyed-water trace at the inlet to observe discharge at the matching weep within a set time, a smoke-pencil to confirm airflow under light negative pressure, and a controlled hose spray around the weep line. Combine results with borescope photos for robust, non-destructive verification.

Question: What are typical acceptance cues for adequate weep and drainage performance?

Look for weep diameters of 6–10 mm, spacing between 400–600 mm, outward sill slope of at least 1:15, baffle alignment within 3 mm, and cavity airflow visible on a smoke test at 25–50 Pa. Tests should show timely discharge and no interior leakage under controlled spray.

Question: How do we address blocked weeps discovered late in the program?

Clear the blockage with a nylon probe or low-pressure air, adjust any obstructing packers or sealant, then repeat dyed-water and spray tests to confirm restored flow. Document before/after photos, batch numbers if sealant repairs are made, and obtain sign-off per approved project specifications and authority requirements.

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