Stucco Slider Replacement With Out-of-Plumb Frame and Threshold Leak
A 1985 stucco-clad house has a 6 ft sliding glass door opening onto a patio. The rough opening is 72 in. by 80 in.; interior tile is 1/2 in. above the slab, and the exterior patio is 1 1/2 in. below the interior floor. The door leaks at the threshold corners during wind-driven rain, the operable panel drags, and a level check shows the frame is out of plumb 3/8 in. over its height. The 2x8 header has about 1/4 in. of sag, and hairline cracks radiate from the opening corners in the stucco. The homeowner wants a new flanged vinyl slider and does not want stucco removed. The new unit is 6 ft 8 in. tall with a 4 9/16 in. jamb. The room is a family room, not a bedroom, and the door is the main path to the backyard.
1. Is a no-stucco-removal flanged installation viable? What are the practical options?
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A flanged door surface-mounted over stucco and sealed at the flange is not a reliable installation. It creates a face-sealed joint that cannot drain, and stucco is not a dependable flashing surface. The practical options are to remove stucco around the opening to expose the weather barrier and sheathing, install the flanged door with a pan flashing and head flashing integrated with that barrier, then repair the stucco with proper casing bead and weep details; or use a block-frame door designed for the opening with a pan flashing and a deliberate stucco reveal. Either way, the 3/8 in. out-of-plumb and the 1/4 in. header sag must be evaluated before ordering. If the framing is corrected so the door sits plumb and level, the new unit can perform; if the door is shimmed into a twisted opening, the panel will drag. The family room use does not trigger bedroom egress, but the door is the main path and must operate freely.
2. Describe the threshold and pan-flashing sequence, including how it should integrate with the stucco.
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Remove the old door and enough stucco to expose the sill and the weather barrier. Inspect and repair any rot at the sill or framing. Install a sloped pan flashing with a back dam and end dams that drain to the exterior, and integrate the pan with the barrier at the sides. Set the door in a bed of sealant on the pan, shim at the jambs and sill, check plumb and level, and anchor through the frame into framing. Install head flashing over the top flange and lap the barrier above over it. The stucco must terminate above the flashing with a weep screed or casing bead so water can escape; do not bury the flashing in stucco or seal the weep path. Use backer rod and sealant at joints that must be sealed, and leave intentional drainage openings open. Water-test the threshold before final stucco repair.
3. What structural and ordering checks should be completed before the new door is purchased?
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Check the header, jack studs, king studs, and sill for sag, rot, or movement. A 1/4 in. header sag may be cosmetic or may indicate a structural issue, but the door cannot be ordered and installed as if the opening were plumb. Correct the frame so the new door can be installed plumb, level, and square; do not use shims to hide a twisted opening. Verify the rough opening width and height after stucco removal, because the exposed opening may differ from the finished stucco opening. Confirm the jamb depth against the wall thickness and interior tile transition, and confirm the threshold height relative to the patio and interior floor. Check the manufacturer instructions for pan-flashing requirements and anchoring. Order only after field verification, and include a contingency for framing repair and stucco patching in the schedule.