Case Study · SB 721 · CSLB #1060736

Balcony Waterproofing & Reconstruction — Apartment Walkway, San Jose

The walkway read as concrete and the railing read as tired. Both were wrong: the surface was a cement topping on a wood deck, and the railing was the reason it leaked.

San Jose, CATwo-story stucco apartment buildingCompleted Q2 2025

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Waterproofing

Project facts

Location: San Jose, CA
Service: Balcony Waterproofing
Property: Two-story stucco apartment building
Units: 8
Elevated elements: One elevated walkway serving the upper units, plus the exterior stair run
Client: Owner / property management company
Scope: Tear-off of the worn topping and decking, framing and ledger repair, new sloped plywood, new aluminum guardrails and stair handrail, Westcoat lath-and-slurry waterproofing with textured topcoat
Timeline: 2 weeks
Completed: Q2 2025
Budget range: $18k–$28k

Compliance context · SB 721

SB 721 lists the guardrail and the waterproofing as separate items, and owners routinely price them as separate jobs, often a season apart. On a wood-framed walkway they cannot be separated, because every guardrail post is a hole through the waterproofing. Seal the deck in spring and set the posts in autumn and you have drilled a row of new penetrations through the surface you just paid for — and an inspector will find them, because post bases are the first place a report looks for standing water and soft framing. The order that works is the one in these photos: framing, then the posts, then the lath and the coating carried up around every base as one continuous surface.

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Balcony Waterproofing

01 The situation

The challenge

The walkway read as concrete. Hard grey surface, solid underfoot, and the only thing on it that looked its age was the railing — cream paint, square wood posts, the bottom rail soft where it met the deck. The surface was not concrete. It was a cement topping over a wood-framed deck, and along the line residents actually walk, from the head of the stair to their own door, it had worn through in patches to the layer underneath. The railing made that worse rather than better. Every post was bolted down through the topping, so each base was somewhere for water to stand and somewhere for it to get in — and none of it could be fixed by recoating around them.

02 Execution

What we did

The order of the work mattered as much as the work itself:

Stripped the worn topping and decking back to the joists and checked the framing, the wall ledger and the deck-to-threshold junction at each unit door

Replaced the damaged framing and laid new plywood with positive slope away from the building

Set the new powder-coated aluminum guardrail posts and the stair railings before any coating went down, so every base could be sealed into the surface rather than drilled through it

Installed the Westcoat lath-and-slurry system across the deck, turned it up the wall and out over the edge, and finished with the textured topcoat

03 Outcome

The result

1walkway rebuilt from the joists up

2railings replaced — walkway guard and stair run

2 wkstear-out to final topcoat

The walkway is now a wood-framed deck that behaves like one: new plywood with slope, a lath-and-slurry surface bonded to it rather than sitting on it, and a railing whose post bases are sealed into that surface instead of drilled through it afterwards. The stair got the same pass — new guards and a wall-mounted graspable handrail on the run up to the door. Residents cross one continuous waterproof surface from the head of the stair to their own threshold, and the SB 721 items for the guard and for the walking surface closed together instead of in two rounds.

Results at a glance

Elevated walkway rebuilt from the joists up and re-surfaced with a bonded lath-and-slurry waterproofing system
Painted wood guardrail replaced with powder-coated aluminum, posts set before the coating went down
Exterior stair given new guards and a wall-mounted graspable handrail
Deck sloped away from the building and detailed at the wall, the edge and every unit threshold

What the client received

SB 721 closure covering the guard, the stair and the walking surface in one pass
Westcoat system warranty plus our workmanship warranty
Photo record of the framing and the wall ledger before the new plywood went down
Threshold and wall detail documented at each unit door
Maintenance schedule running through to the next inspection cycle

Transformation