NYC Bathroom Remodeling — Wet-Over-Dry, DOB LAA, Waterproofing Standards

NYC bathroom remodels fail in two places: permitting and waterproofing. Get either one wrong and you are looking at a leak claim in a downstairs unit, a stop-work order from DOB, or an Alteration Agreement default that your co-op board can escalate. In Manhattan co-ops built before 1960, you are replumbing inside walls that have seen three prior renovations — each one cheaper than the last — and the water column behind your tile may have been re-routed by a contractor in 1987 who never pulled a permit.

AskBaily sends your NYC bathroom remodel to one licensed NYC HIC + DOB-registered GC who understands LAA filings, co-op Alteration Agreements, and the actual waterproofing standard for a pre-war tenement vs a post-war elevator building vs a new-construction condo.

What a DOB-filed NYC bathroom looks like

• LAA Type 1/2/3 for fixture-only replacement with no plumbing relocation.
• Alt-2 if you move the toilet stack, add a second bath, or penetrate a riser.
• Architect/PE sign-off on any Alt-2.
• Co-op Alteration Agreement + $2M GL + workers' comp insurance COI.
• HPD ACP5 for pre-1987, XRF lead-paint for pre-1960.

Waterproofing that meets NYC code

The legal minimum is ANSI A118.10-compliant waterproof membrane to the pan — Schluter Kerdi, Laticrete Hydro Ban, or Mapei Mapelastic — wrapped up the walls to shower-head height plus 6 inches. In a co-op with downstairs neighbors, you want a second redundancy: a traditional lead or hot-mopped pan under the membrane. That is what keeps a pinhole leak from becoming a Small Claims Court filing.

Frequently asked questions

Do I need a permit to redo my NYC bathroom? If you are replacing a toilet, vanity, and tile in place, an LAA Type 1 is often enough. If you move the toilet's rough-in, relocate the shower, or add a bath, Alt-2 is required with architect sign-off.

What is the wet-over-dry rule for bathrooms? Same as kitchens — most co-op Alteration Agreements block placing new bathrooms over downstairs neighbors' dry rooms. Existing stacks are typically grandfathered.

Why are NYC bathroom remodels so expensive? Small square footage, high labor cost, co-op insurance requirements, DOB filing fees, filing representative fees, and waterproofing to a standard that survives downstairs-neighbor scrutiny. $45K-$125K is normal for a mid-tier Manhattan co-op bath.

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