Replace a Damaged Window or Door Casing Assembly

A. Finished-Project Specification

Deliverable: one interior window or non-rated door opening with the damaged casing assembly removed, the jamb inspected and accepted, and a complete matching replacement casing assembly installed, fastened, filled, caulked, primed, and finished to the approved room standard.

B. Component Schedule

Component	Quantity	Material	Finished Size	Preparation
Head casing	1 per opening	Matched to existing profile and species/material	Cut to verified head-jamb width plus joint allowance	Test-cut and dry-fit before final cut
Side casing (legs)	2 per opening	Matched to existing profile and species/material	Cut to verified floor-to-head or sill-to-head length	Test-cut and dry-fit before final cut
Rosette or plinth block (if the existing system uses one)	As required by existing system	Matched to existing block profile and material	Matched to existing block dimensions	Dry-fit against adjoining casing before fastening

C. Material Takeoff

• Casing stock: matched profile, thickness, and width, purchased in lengths sufficient to cut all head and side pieces from the fewest joints practical, plus a minimum 10 percent waste allowance for test cuts.
• Fasteners: finish nails sized to penetrate the casing and seat a minimum of 1 inch into verified jamb or framing backing, in the gauge specified by the approved trim system.
• Filler and sealant: compatible wood filler for fastener holes and paintable caulk for approved wall-to-casing joints only.
• Finish materials: primer and topcoat matching the existing color formula, sheen, and coating system, in a quantity sufficient for two coats over the entire replacement assembly.

D. Fastener and Hardware Schedule

Joint	Fastener	Length	Spacing	Notes
Casing to jamb edge	Finish nail matched to trim system	Sized to penetrate jamb without exiting the far face	Every 16 inches along the jamb edge	Angle slightly to increase holding power; keep clear of glass and hardware
Casing to wall framing/backing	Finish nail matched to trim system	Sized to seat a minimum 1 inch into verified framing	Every 16 inches along the outer casing edge	Confirm framing location with a stud or utility locator before driving
Mitered or coped corner joint	Finish nail or brad matched to trim system	Sized to lock the joint without splitting the profile	One to two fasteners per corner	Pre-drill thin or hardwood profiles to prevent splitting

E. Preparation — Identification and Documentation (Steps 1–4)

1. Identify the opening type, casing profile, material, width, thickness, joint style, stool or apron condition, jamb extension, reveal, finish, and adjacent wall texture. Record each characteristic on the project record, measuring the existing reveal at the head and both side jambs with a reveal gauge before any removal begins.
2. Confirm that the project does not alter the window installation, exterior water-management system, rated door assembly, egress opening, or structural header. Verify this against the Chapter 1 readiness decision and risk register; do not proceed until every exclusion is confirmed in writing.
3. Check for hazardous coatings before disturbing painted casing or adjacent wall finish. Complete the required assessment and apply the corresponding containment and work-method controls before any sanding, scraping, or cutting of painted material.
4. Photograph all joints, reveals, returns, transitions, and defects. Photograph the full opening and close-up views of each corner joint, the stool or apron, and any visible damage before touching the casing.

F. Cause Identification and Removal (Steps 5–10)

1. Determine whether casing damage was caused by moisture, jamb movement, window leakage, door-frame movement, impact, or finish failure. Record the suspected cause as an observed fact or a suspected concealed condition, consistent with the Chapter 1 fact-labeling standard.
2. Correct or refer the underlying opening or moisture problem before installing new casing. Do not install replacement casing over an unresolved leak, movement, or moisture condition; stop and refer it to the qualified trade identified in the risk register.
3. Score paint and caulk lines along the wall and jamb. Run a utility knife along every painted or caulked seam between the casing and the wall or jamb to reduce tear-out during removal.
4. Remove hardware, blinds, curtains, stops, or accessories only where authorized. Label and store each removed item, and leave any item not authorized for removal in place and protected.
5. Release casing progressively with protective blocks and remove fasteners safely. Work from one end of each piece to the other, using a protective block behind the pry bar at every contact point with the wall or jamb, and set aside removed fasteners for controlled disposal.
6. Preserve one representative piece for profile and finish matching. Select the least-damaged full-length piece removed and store it flat until the replacement casing has been finished and accepted.

G. Jamb Inspection (Steps 11–13)

1. Inspect jambs, jamb extensions, framing edges, shims, backing, drywall, plaster, moisture, and fastener damage. Record each finding as an observed fact, including shim condition, gaps, and any staining or softness detected by probing with a screwdriver or moisture meter.
2. Stop if the opening is loose, leaking, decayed, structurally distorted, or part of an unresolved rated assembly. Halt work immediately, protect the open jamb from further disturbance and weather, and refer the condition per the risk register before continuing.
3. Repair minor accepted wall-edge, jamb, backing, or shim conditions. Complete only the minor repairs the approved scope allows, using compatible materials, and re-inspect the repaired area before proceeding to layout.

H. Layout, Cutting, and Dry-Fit (Steps 14–20)

1. Select replacement casing matching the approved profile and thickness. Confirm the selected stock matches the preserved sample piece in profile, width, and thickness before cutting any piece to length.
2. Condition material as required and prefinish concealed or difficult surfaces where specified. Allow wood or composite stock to acclimate to the room per the product's requirements, and prefinish any back or edge surface that will be difficult to coat after installation.
3. Establish the reveal around the jamb with a gauge or consistent measurement. Mark the reveal line at the head and both side jambs using the same reveal gauge setting recorded in Step 1.
4. Mark head and side casing intersections using the approved mitered, square, rosette, or other joint system. Lay out each joint location directly from the reveal marks, matching the joint system identified in Step 1.
5. Cut test joints and verify profile alignment. Cut a scrap test joint at each corner angle required and confirm the profile lines match cleanly before cutting the final material.
6. Cut the final casing with supported stock and clean face orientation. Support long pieces fully during the cut, keep the finished face oriented consistently, and label each piece by location immediately after cutting.
7. Dry-fit the full assembly and verify reveal, joint closure, head alignment, floor or stool termination, and wall contact. Hold every piece in place without fasteners and confirm the reveal is consistent at all three jambs, the corner joints close tightly, and the casing sits flat against the wall along its full length.

I. Installation and Fastening (Steps 21–24)

1. Make controlled adjustments without pulling a distorted jamb into position with trim fasteners. Correct any gap by adjusting the casing cut or shimming behind it; do not force a jamb into alignment using nailing pressure.
2. Fasten casing into verified jamb edges, framing, or backing with appropriate fasteners. Confirm framing and backing locations with the stud or utility locator before driving each fastener listed in the Fastener and Hardware Schedule.
3. Keep fasteners clear of glass, window balances, wiring, and door hardware. Verify clearance at every fastener location before driving, and stop if a fastener path would intersect glass, hardware, or a concealed utility.
4. Set and fill fasteners with compatible material. Set every fastener head below the surface with a nail set and fill each hole with the compatible filler identified in the Material Takeoff.

J. Finish and Documentation (Steps 25–29)

1. Caulk approved wall-to-casing joints and finish joints without masking poor fit. Apply the paintable caulk only at the joints the approved finish system specifies; do not use caulk to close a gap that should be corrected by refitting the casing.
2. Prime and finish to the approved color, sheen, and coating system. Sand, prime, and apply the finish coats matching the color formula, sheen, and coating system recorded in Step 1, allowing the required dry time between coats.
3. Reinstall authorized accessories without compromising casing or opening operation. Reinstall any hardware, blinds, curtains, or stops removed in Step 8 and confirm they operate without binding on the new casing.
4. Inspect reveal consistency, miters or square joints, alignment, attachment, finish, jamb condition, and opening operation. Complete the full inspection using the Acceptance Standards below before closing out the project.
5. Document material, finish, repaired cause, and final measurements. Record the casing product, finish product, the cause identified in Step 5 and its correction, and the final reveal measurements on the project record.

K. Acceptance Standards

Check	Standard
Reveal consistency	Reveal measures within 1/16 inch of the recorded target at the head and both side jambs
Joint closure	Mitered, coped, or square joints close without a visible gap greater than the thickness of a business card
Attachment	Every fastener is seated into verified jamb or framing backing, set below the surface, and filled
Wall contact	Casing sits flat against the wall along its full length with no visible bow or gap requiring excess caulk
Finish match	Color, sheen, and texture match the approved sample under normal and raking light
Opening operation	Window or door operates through its full range without binding, rubbing, or contacting the new casing
Jamb acceptance	No unresolved moisture, decay, structural distortion, or rated-assembly condition remains at the inspected jamb