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Safety Cue
Task-specific safety guidance for ordinary work hazards.
Project 07
Install an Exterior Door Sill Pan
Prepare and install a continuous, supported, outward-draining sill-pan system in one exterior-door rough opening, using the door manufacturer's rough-opening requirements and the approved sill-pan detail, so the opening is ready to receive the prehung door installed in Project 08.
Field Cue System
These cues appear at the point of work. They identify safety, code, manufacturer, and measurement issues before they become rework, disputes, or concealed defects.
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Critical Safety Cue
Serious injury or major structural consequence is possible.
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Field Safety Cue
Practical work-area safety: footing, debris, access, and exposure.
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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 sill-pan membrane, primers, and accessories.
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Measurement Cue
Clearance, dimension, tolerance, and reference-point guidance.
Job Overview
This project qualifies you to prepare and install a drained sill-pan system in one exterior-door rough opening before the prehung door is set. The finished work product is a continuous, supported, outward-draining sill pan — extending up both jambs, formed and sealed at both corners, and integrated with the surrounding water-resistive barrier (WRB) — ready to receive the specified prehung door.
You will review the door manufacturer's rough-opening and sill-pan requirements, verify the actual door unit and its dimensions, recheck the rough opening for square, level, plumb, and structural support, clean and slope the sill, install and form the sill-pan membrane or preformed components, seal the corners, integrate the exterior edge with the WRB, and inspect the completed pan for continuity and drainage before it is covered.
This project follows the wall-sheathing acceptance completed in Project 01 and the WRB and seam work completed in Projects 02 and 03. It sits immediately before Project 08, which sets and fastens the prehung exterior door into the sill pan installed here, and it parallels the window sill-pan flashing taught in Project 04.
Skills You Will Demonstrate
- BE-037 — Prepare the exterior-door rough opening, verifying dimensions, structural support, and threshold-bearing condition against the door manufacturer's requirements.
- BE-038 — Create or install the required outward sill slope using the approved tapered material, pan system, or liquid-applied method.
- BE-039 — Install the sill-pan membrane or preformed pan components so the pan extends up both jambs and across the full opening width.
- BE-040 — Form and seal sill-pan corners using approved end dams, back dams, gussets, boots, or liquid flashing.
- BE-041 — Integrate the sill pan's exterior edge with the water-resistive barrier so water discharges to the outside without blocking the drainage path.
- BE-042 — Inspect sill-pan continuity, corner seals, back dam, slope, bearing, and drainage outlet, and document the completed pan before the door is installed.
Where This Skill Fits
The sill pan installed here is the single most consequential water-control detail in the entire door assembly. Every later door project in this book depends on it: the prehung door set in Project 08 relies on the pan's slope and bearing surface, the jamb and head flashing installed in Project 09 relies on the pan's upturned edges to shed water correctly, and the full exterior water-control inspection in Project 19 specifically checks sill-pan drainage as one of its required items. A sill pan that traps water instead of draining it outward will not announce itself until water damage appears at the threshold or subfloor, often long after the siding has concealed the defect.
The sequence used here — verify the opening, slope the sill, install the pan from center or bottom outward, form the corners, and integrate with the WRB — is the same drainage-first method used for the window sill-pan flashing in Project 04. Building that method correctly here will make Project 04's window sill pan, and the full-building review in Project 19, more consistent and reliable.
Scope and Intended Use
This project covers:
- reviewing the door manufacturer's rough-opening dimensions, threshold-support requirements, sill-pan detail, fastening zones, sealant locations, and accessibility or clearance requirements
- verifying the actual door unit, handing, swing, threshold type, frame dimensions, and installation accessories against the rough opening
- measuring the rough opening for width, height, square, level, plumb, floor elevation, and required clearances
- inspecting the rough sill for rot, damage, uneven bearing, protrusions, contamination, and structural deficiency
- creating the required outward sill slope and installing the sill-pan membrane or preformed components
- forming and sealing sill-pan corners and integrating the exterior edge with the WRB
- inspecting and documenting the completed sill pan before the door is installed
This project does not authorize the learner to:
- proceed with sill-pan installation when the opening, floor, framing, or threshold-support condition falls outside the door manufacturer's permitted adjustment range
- select a sill-pan system, membrane, or slope material independently of the approved door schedule and manufacturer instructions
- block the sill-pan's drainage outlet with sealant, fill material, or an unapproved back-dam detail
- set the prehung door before this project's sill-pan inspection is complete and any required correction has been made
Any rough-opening, floor, or structural condition that falls outside the approved adjustment range must stop work in that opening until qualified review and direction are obtained.
Reference Conventions
Establish these references before any sill-pan installation or correction begins, and do not change them once the pan inspection is complete.
| Term | Definition |
|---|---|
| Sill pan | The membrane or preformed drainage system installed across the rough-opening sill and up both jambs to direct incidental water outward before the door is set |
| Back dam | The raised interior edge of the sill pan that prevents water from moving inward past the threshold |
| End dam | The formed or applied component at each end of the sill pan that closes the corner and directs water outward rather than off the jamb ends |
| Threshold support | The bearing surface and shims required to support the door threshold at the manufacturer-specified elevation and slope |
| Drainage outlet | The open exterior edge of the sill pan where incidental water is designed to exit the assembly; never sealed or blocked |
| Permitted adjustment range | The dimensional tolerance for rough-opening width, height, square, level, plumb, and floor elevation stated by the door manufacturer and the approved door schedule |
Sill-Pan Reference Record
Before beginning any pan installation, record the controlling documents and reference data directly on the sill-pan inspection record:
Opening ID: ______ Door schedule reference: ______ Sill-pan system/product: ______ Manufacturer instruction revision: ______
Date started: ____________ Builder name: ____________
Prerequisites
- Envelope-readiness decision from Project 01 issued as proceed or conditional-proceed for this opening
- WRB installed and seam-treated at this opening under Projects 02 and 03
- Door manufacturer's rough-opening requirements, threshold-support specification, and sill-pan detail available on site
- Actual door unit identified, including handing, swing, threshold type, and frame dimensions
- Approved sill-pan system, membrane or preformed components, primer, and compatible sealant on site
- A means to contact the responsible design professional or general contractor for discrepancies outside this project's authorized adjustment range
Common Field Fundamentals
Every sill-pan detail in this book, whether at a door in this project or a window in Project 04, follows the same drainage logic: the pan must slope outward, its corners must be closed against inward water movement while remaining open at the exterior edge, and its upturned jamb legs must integrate with the WRB above so water sheds down and out rather than behind the pan.
Opening verificationRough opening measured and compared against the door schedule
Slope and prepSill cleaned and sloped outward before membrane installation
Pan installationMembrane or preformed pan installed center-out with jamb upturns
Corners and WRB integrationEnd dams formed and the exterior edge tied into the WRB
Separating Authorized Correction From Qualified Review
An opening that is out of square, undersized, oversized, or has an unsupported or deteriorated sill beyond the door manufacturer's permitted adjustment range is not something this project authorizes you to correct independently. Mark it, record it, and obtain qualified review before proceeding. A minor sill-slope build-up using the approved tapered material within the permitted range is an authorized part of this project's scope.
BE-037 – BE-042
Preparation / Installation / Inspection Qualification
Exterior Door Sill-Pan Installation
A. Finished-Project Specification
Scope: one completed sill-pan installation covering the full width of one scheduled exterior-door rough opening, extending up both jambs, with both corners formed and sealed and the exterior edge integrated with the surrounding WRB.
B. Required Documentation Schedule
| Document | Source | Confirmation Required |
|---|---|---|
| Door manufacturer's rough-opening requirements | Door manufacturer | Width, height, and clearance values confirmed for the actual scheduled unit |
| Sill-pan system detail | Door manufacturer / envelope specification | Membrane or preformed-pan product and installation sequence confirmed |
| Door schedule | Design professional / plan set | Unit identification, handing, swing, and threshold type confirmed for this opening |
| Prior envelope-readiness record | Project 01 record | Opening confirmed proceed or conditional-proceed before sill-pan work begins |
| WRB and seam records | Project 02–03 records | Confirmed installed and inspected at this opening |
C. Preparation Materials and Consumables
- Sill-pan membrane or preformed components: matching the approved sill-pan detail, cut to the controlled dimensions required for this opening only.
- Slope material: approved tapered sill-slope material or liquid-applied slope system, limited to the door manufacturer's permitted range.
- Primer: compatible primer specified by the sill-pan manufacturer, applied only where required.
- Corner-forming accessories: preformed corner boots, end dams, gussets, or liquid flashing compatible with the selected sill-pan system.
- Sealant: compatible sealant for designated joints only, not for the drainage outlet.
- Documentation: one sill-pan inspection record per opening.
D. Acceptance Standards
| Check | Standard |
|---|---|
| Rough-opening dimensions | Width, height, square, level, plumb, and floor elevation within the door manufacturer's permitted adjustment range |
| Sill slope | Slopes outward per the approved tapered material, pan system, or liquid-applied detail, without reducing required opening dimensions |
| Pan continuity | Membrane or preformed pan extends up both jambs and across the full opening width without gaps, wrinkles, or punctures |
| Corner seals | Both corners formed and sealed using approved end dams, back dams, gussets, boots, or liquid flashing with no visible gap or void |
| Back dam | Present and continuous where required to prevent inward water movement |
| Drainage outlet | Exterior edge remains open and unsealed; not filled with sealant or bridged with debris |
| WRB integration | Exterior edge of the pan overlaps or is overlapped by the surrounding WRB so water discharges outward in shingle-lap order |
| Threshold bearing | Full, level bearing surface established at the elevation required for the scheduled door unit |
E. Document Review and Opening Verification (Steps 1–3)
- Review the door manufacturer's rough-opening dimensions, threshold support requirements, sill-pan detail, fastening zones, sealant locations, and accessibility or clearance requirements. Confirm the current revision against the project's document-control log before using it.
- Verify the actual door unit, handing, swing, threshold type, frame dimensions, and installation accessories. Confirm the unit identification matches the door schedule for this opening.
- Measure the rough opening for width, height, square, level, plumb, floor elevation, and required interior and exterior clearances. Record each value against the door manufacturer's permitted adjustment range.
F. Sill Inspection and Preparation (Steps 4–8)
- Inspect the rough sill for rot, damage, uneven bearing, protrusions, contamination, and structural deficiency. Use a moisture meter where staining or softness is observed.
- Stop work if the opening, floor, framing, or threshold support condition falls outside the approved adjustment range. Mark the condition and obtain qualified review before continuing.
- Clean and prepare the sill and lower jambs. Remove debris, dust, and contamination using the sill-pan manufacturer's approved method.
- Create the required outward slope using the approved tapered material, pan system, or liquid-applied method. Confirm the resulting opening dimensions remain within the permitted range after the slope material is installed.
- Install corner guards, back dams, end dams, or preformed sill-pan components required by the selected system. Dry-fit these components before applying primer or adhesive.
G. Pan Installation and Corner Forming (Steps 9–16)
- Dry-fit the sill-pan components and confirm full threshold support and exterior drainage. Correct any interference before proceeding to cutting.
- Cut membrane or preformed-pan components to the controlled dimensions required for this opening. Reference the door manufacturer's rough-opening dimensions rather than an estimated length.
- Apply required primer or compatible sealant at specified joints. Observe the manufacturer's specified open time before installing membrane.
- Install the sill pan so it extends up the jambs and across the full opening width. Work from the center outward without stretching the membrane through the corners.
- Form and seal corners using approved end dams, back dams, gussets, boots, or liquid flashing. Confirm full contact and no visible gap at each formed corner.
- Integrate the exterior edge with the WRB so water discharges to the outside. Lap the pan's exterior edge beneath the surrounding WRB in shingle-lap order.
- Maintain an interior back dam where required to prevent inward water movement. Confirm the back dam remains continuous across the full opening width.
- Do not block pan outlets or fill the drainage path with sealant. Leave the exterior edge of the pan open to drain.
H. Support, Inspection, and Documentation (Steps 17–20)
- Install threshold support shims or bearing components only where required by the door manufacturer. Use only the shim material and locations specified for the scheduled unit.
- Inspect pan continuity, corner seals, back dam, end dams, slope, bearing, and drainage outlet. Confirm every item against the Acceptance Standards table before proceeding.
- Repair punctures, wrinkles, gaps, and incomplete corners using the approved method. Do not conceal an unresolved defect with sealant alone.
- Protect the completed sill pan from foot traffic and door-handling damage. Cover or barricade the opening until the door is ready to be set.
- Photograph and document the pan before the door is installed. Label each photograph with the opening ID for later reference.
Common Verification Inspection
Inspect every completed sill pan using the same checks regardless of which opening it covers.
- Documentation check: confirm the door manufacturer's rough-opening and sill-pan requirements and the door schedule are current and referenced on the sill-pan inspection record.
- Opening check: confirm the rough opening matches its schedule for dimension, square, level, plumb, and floor elevation within the permitted range.
- Slope check: confirm the sill slopes outward without reducing the required opening dimensions.
- Pan continuity check: confirm the pan extends up both jambs and across the full opening width without gaps, wrinkles, or punctures.
- Corner check: confirm both corners are formed and sealed with no visible gap or void.
- Drainage check: confirm the exterior edge remains open and the back dam remains continuous.
- WRB integration check: confirm the exterior edge of the pan is integrated with the surrounding WRB in shingle-lap order.
Complete the Sill-Pan Inspection Record in the Inspection Checklist section below before beginning Project 08.
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Failure Points and Troubleshooting
Cleanup
This project ends with a continuous, supported, outward-draining sill pan and a documented inspection record, not with the prehung door installed.
- Clear debris, release-film backing, and trimmed membrane scraps from the opening and surrounding floor or grade
- Remove masking or temporary marking materials that are not part of an open deficiency reference
- Cover or otherwise protect the completed sill pan from foot traffic and door-handling damage before leaving the site
- Store the sill-pan inspection record and supporting photographs with the project's permanent documentation
- Communicate any open discrepancy and its required decision to the responsible design professional or general contractor before Project 08 begins
Field Terms
- Sill Pan
- The membrane or preformed drainage system installed across the rough-opening sill and up both jambs before the door is set.
- Back Dam
- The raised interior edge of the sill pan that prevents water from moving inward past the threshold.
- End Dam
- The formed or applied component at each end of the sill pan that closes the corner and directs water outward.
- Threshold Support
- The bearing surface and shims required to support the door threshold at the manufacturer-specified elevation and slope.
- Drainage Outlet
- The open exterior edge of the sill pan where incidental water is designed to exit the assembly.
- Permitted Adjustment Range
- The dimensional tolerance for rough-opening conditions stated by the door manufacturer and the approved door schedule.
- Shingle-Lap Order
- The layered sequence in which upper water-control layers discharge onto lower layers so water sheds downward and outward.
- Qualified Review
- Evaluation of a condition by the design professional, structural engineer, or authority having jurisdiction, beyond this project's authorized scope.
Skill Check
- Why must the actual door unit and its manufacturer's rough-opening requirements be confirmed before the rough opening is remeasured?
- What must happen if the rough opening, floor, or threshold-support condition falls outside the door manufacturer's permitted adjustment range?
- Why must the sill be sloped outward before the pan membrane is installed rather than relying on the membrane alone to direct water?
- What is the function of a back dam, and why must it remain continuous across the full opening width?
- Why must the sill pan's exterior edge be integrated with the WRB in shingle-lap order rather than simply placed beside it?
- Why is sealing or filling the drainage outlet considered a defect rather than an improvement?
- What must the learner do upon finding a corner with a visible gap or incomplete adhesion?
- Why must the completed sill pan be protected from foot traffic before the door is installed?
- What must be recorded on the sill-pan inspection record before Project 08 begins?
- Why does this project's method mirror the window sill-pan flashing taught in Project 04?
Competency Rubric
| Competency | Independent Pass Standard | Not Demonstrated | With Assistance | Independently |
|---|---|---|---|---|
| BE-037 | Prepares the exterior-door rough opening, verifying dimensions, structural support, and threshold-bearing condition against the door manufacturer's requirements | |||
| BE-038 | Creates or installs the required outward sill slope using the approved tapered material, pan system, or liquid-applied method | |||
| BE-039 | Installs the sill-pan membrane or preformed pan components so the pan extends up both jambs and across the full opening width | |||
| BE-040 | Forms and seals sill-pan corners using approved end dams, back dams, gussets, boots, or liquid flashing | |||
| BE-041 | Integrates the sill pan's exterior edge with the water-resistive barrier so water discharges outward without blocking drainage | |||
| BE-042 | Inspects sill-pan continuity, corner seals, back dam, slope, bearing, and drainage outlet, and documents the completed pan before the door is installed |
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 — Sill-Pan Record
| Check | Plan Value / Requirement | Field Value | Within Tolerance (Y/N) | Correction (if any) |
|---|---|---|---|---|
| Rough-opening dimensions | Matches door schedule within permitted range | |||
| Rough-opening square/level/plumb | Within permitted adjustment range | |||
| Sill condition | Free of rot, damage, uneven bearing, and contamination | |||
| Sill slope | Slopes outward per approved detail | |||
| Pan continuity | Extends up both jambs and across full opening width | |||
| Corner seals | Formed and sealed with no visible gap or void | |||
| Back dam | Continuous across full opening width | |||
| Drainage outlet | Open and unobstructed | |||
| WRB integration | Exterior edge laps correctly with surrounding WRB | |||
| Threshold bearing | Full, level bearing at required elevation |
Open discrepancies attached: ____________ Responsible authority for each: ____________
Sill-pan decision: ______ (Proceed/Conditional-Proceed/Stop-Work) Date: ____________ Builder name: ____________
Performance Check
With document review, opening verification, sill preparation, pan installation, corner forming, and WRB integration complete, review the sill pan against the Acceptance Standards table and confirm the rough opening remains within the permitted adjustment range, the sill slopes outward, the pan is continuous up both jambs with no gaps or punctures, both corners are formed and sealed, the back dam is continuous, the drainage outlet remains open, and the exterior edge is integrated with the WRB in shingle-lap order. Complete and sign the sill-pan inspection record before the prehung door is set in Project 08. If a discrepancy remains open, identify the responsible authority and required decision before proceeding.
Project Closeout
You have completed the seventh project in the building-envelope sequence: installing an exterior-door sill pan. This project required you to prepare the exterior-door rough opening and verify it against the manufacturer's requirements (BE-037), create the required outward sill slope (BE-038), install the sill-pan membrane or preformed components across the full opening width (BE-039), form and seal the sill-pan corners (BE-040), integrate the pan's exterior edge with the water-resistive barrier (BE-041), and inspect and document the completed pan before the door is installed (BE-042).
You now have a continuous, supported, outward-draining exterior-door sill pan with a signed sill-pan inspection record. That decision carries directly into the next project: setting, aligning, fastening, and function-testing the specified prehung exterior door in this prepared opening.
Protect the completed sill slope, corner seals, and WRB integration established in this project. Project 08 sets the prehung door onto this sill pan and depends on every condition confirmed here.