If you own a small building in the Bronx and your gas bill jumped $400 last January while a tenant was still texting you about a cold bedroom, the leak was almost certainly around the windows and doors — not the boiler. The good news: Bronx landlords generally spend less than New Rochelle landlords getting ahead of this, and most of the work is genuinely owner-doable. Here's how the numbers actually shake out for fall 2026, and what you can handle yourself before the first real cold snap.
The short answer: Bronx wins on vendor pricing, New Rochelle wins on nothing
Across the 100+ Bronx buildings we help manage, fall sealing on a typical 6-unit walk-up runs $800–$1,500 if you hire it out completely, or closer to $150–$250 in materials if you do the caulking and weatherstripping yourself and only call a pro for the one or two frames that are actually rotted.
In New Rochelle, the same job tends to come in 15–30% higher — not because the labor is fancier, but because the vendor pool is thinner, call-out minimums are stricter, and most crews build in Westchester drive time. We've had Bronx clients get three quotes in a week; our New Rochelle owners often wait ten days for a second bid.
Side-by-side: what a 6-unit fall seal-up actually costs
| Line item | Bronx (2026) | New Rochelle (2026) |
|---|---|---|
| Vendor call-out / inspection | $75–$150 | $125–$200 |
| Trade labor, per hour | $45–$65 | $60–$85 |
| Full perimeter re-caulk, 6 units | $800–$1,500 | $1,100–$1,900 |
| Replace one deteriorated window frame | $300–$600 | $425–$750 |
| DIY materials only (caulk + weatherstrip) | $150–$250 | $150–$250 |
Materials cost the same at any Home Depot. The gap is entirely labor and travel.
What's actually failing on your windows and doors
Before you spend a dollar, it helps to know what you're looking at. Two things seal a window or exterior door: caulk (the rubbery bead between the frame and the wall — it keeps water and air out of the gap on the outside) and weatherstripping (the fuzzy or rubber strip inside the sash or door jamb that squishes shut when the window closes).
Both fail from thermal cycling — the daily expansion and contraction that happens when a heated apartment sits against a 20°F brick wall — plus UV from the sun. You'll see:
- Visible cracks or gaps in the caulk bead outside the window
- Weatherstripping that's gone flat, brittle, or peeled away from the sash
- A faint whistle in a windstorm
- Condensation or frost between the panes (that one usually means the double-pane seal is blown — a window problem, not a caulk problem)
- A cold draft you can feel along the sill or at the bottom of the door
If you walk your building in late September with the back of your hand along every sill, you'll find 80% of your leaks in about 20 minutes.
What you can DIY and what you absolutely cannot
In NYC, caulking and weatherstripping on an existing residential building does not require a DOB permit. You can legally do all of it yourself, and most Bronx owners should. Here's the honest split:
Fine to DIY:
- Scraping out cracked exterior caulk and re-running a bead of silicone or polyurethane sealant
- Replacing door weatherstripping (the self-adhesive foam or V-strip kind)
- Installing a new door sweep on the bottom of an exterior door
- Re-glazing a loose pane with new putty on a single-pane window
Call a licensed contractor:
- Full window frame or sash replacement
- Any work on a lintel (the structural beam above a window) — this is a DOB-permitted job
- Anything touching more than 25% of the facade, which pulls you into Local Law 11 facade territory and requires licensed oversight
- Rotted sills where you can push a screwdriver into the wood — that's water damage behind the frame, not a caulk problem
If you're unsure where you stand on the compliance side, our NYC Landlord Compliance Guide walks through what triggers a permit versus what doesn't.
The deadline that actually matters: September 15
NYC heat season runs October 1 through May 31. Once October 1 hits, if your tenant can prove the apartment can't hold 68°F when it's below 55°F outside during the day, you're looking at a Class C HPD violation — the most serious tier, and the one that gets fined fastest.
A leaky window won't be the only cause, but it stacks with a tired boiler and cold radiators to push you over the line. (If your radiators are also hissing or cold at the top, our write-up on whether your Bronx radiators need a fall bleed pairs well with this one — the two fixes together solve most "my apartment is freezing" calls.)
Target mid-September for the walkthrough. Vendors get booked solid by October 10 every year, and the ones taking calls in November are the ones nobody else wanted.
How long the work actually takes
So you have a realistic sense of your Saturday:
- Re-caulking one window: 30–45 minutes including scraping the old bead
- Installing weatherstripping on one door: 15–20 minutes
- New door sweep: 10 minutes with a cordless drill
- Walking a 6-unit building and marking every leak with painter's tape: about an hour
One landlord in Mott Haven did his entire 4-unit brownstone in a single Saturday last October for $180 in materials. His January gas bill dropped $340 compared to the year before. That's the actual math.
What to document (so a tenant complaint doesn't become a violation)
NYC Housing Maintenance Code requires windows and doors be kept weathertight and free of holes or missing putty. If HPD shows up on a cold-apartment complaint, you want proof you addressed it. Keep:
- Date-stamped photos of each window before and after
- Receipts for caulk, weatherstripping, and any vendor invoices
- A one-line note per unit: "Unit 3R, living room window, re-caulked 9/22/26"
DoryAngel clients get these fall tasks flagged automatically in their weekly digest, with the September 15 target date built in — but a notes app and a shared folder work just as well if you're self-managing.
The same cost logic shows up in other fall categories too. If you're pricing out the full pre-winter list, our breakdowns on Bronx vs. Mount Vernon boiler prep and Bronx vs. Mount Vernon fall roof and gutter work show the same pattern — the Bronx vendor market is deeper, which keeps your per-unit cost down almost everywhere.
Sealing windows and doors isn't the most exciting Saturday project. But it's one of the few building jobs where two hours of your own time, a $12 tube of silicone, and a mid-September deadline can save you a four-figure heating bill and a Class C violation. Walk the building this weekend.
