Renovation times will vary by project but there are accepted averages for brownstones versus co-ops and condos, and for one-off projects like renovating a kitchen or bathroom. Keep in mind that the active construction or “build” time--demolition, framing, plumbing, electrical work, tiling, and installing fixtures and finishes--is only one part of the nose-to-tail renovation process.
Brownstone renovation time: It’s safe to say you are looking at six to eight months of active build time, with rooftop or rear extensions (such as expanding the kitchen in the back or building a structure up top) taking longer. Start to finish, most brownstone renovations require a minimum of twelve months to complete. The more changes you make to the layout—and reconfigure systems like HVAC, electrical, and plumbing—the more regulatory challenges you’ll encounter, which eat up time. Roofing and structural repairs will add time too, as will obtaining any Landmark Commission approvals.
Co-op and condo renovation time: Plan on four to six months construction time (and keep in mind that many co-op and condo buildings restrict project length to 4 months, levying a daily fine on projects that take longer). Although the work is typically less involved than brownstones (no roofing or foundational concerns, for example), the added layer of approvals tends and restricted work hours tend to make up for any reduced build-phase time, such that twelve months is the average start-to-finish time.
Kitchens: Upgrading cabinets, countertops, and/or fixtures might take only a matter of weeks. But if you’re completely renovating your kitchen, plan on more like ten to twelve weeks for the active build phase, and total of six months from planning to completion.
Bathrooms: The construction time for a typical reno is four to six weeks, with the total process taking about four months. This also applies to the addition of another bathroom.
Combinations: Safe to say vertical combinations will take longer than horizontal ones in terms of getting board approvals, DOB permits and inspections, and fabrication and installation of the staircase. Expect at least six months for those. But also note that some co-op boards limit combinations to one per year, so you may have to get on a waiting list. Co-op boards usually require you to combine the units within a certain time or face a penalty, in case you were planning on putting off the work for a while. Condos don’t generally have those restrictions but there’ll be more red tape in a condo because you have to change the declaration and also file for a new tax lot with the Department of Finance before you file a permit with the DOB.