Apartment Window Leak Repair — Find the Source, Then Fix It
Tenants are sending photos of wet sills and stained drywall under the windows every time it rains, and you need to know whether it is the windows or the building.
Reply within one business day. Or call / text 763-204-2099.
Apartment window leak repair starts by finding whether the water comes through the window or from the wall, roof edge or balcony above it. JMB Builders traces it, then reseals, pulls and reflashes the window with a sill pan, or replaces it, with interior drywall repair as its own line. Low-rise apartment buildings across the Twin Cities metro to St. Cloud, priced per opening. Send photos for a reply within one business day, or book a free in-home estimate.
- Priced per opening, drywall a separate line
- Source traced before anything is replaced
- Worst units and stacks scheduled first
Water at the bottom of an apartment window does not prove the window leaks. On a multistory building it often comes from above: a balcony deck draining against the wall, a failed joint in the siding, a missing head flashing on the window one floor up, or the roof edge. Replacing the window under that leak leaves you with a new window and the same stain.
We start with the pattern. Which units, which elevation, which stack, and whether it shows in wind-driven rain or every rain. Then we water-test from the bottom of the opening up, open trim where needed, and trace it. The fix follows the source: new sealant at the frame, a window pulled and reinstalled on a sill pan with new flashing tape, or a window replaced when the frame or glass seal itself has failed.
Damaged drywall and trim inside are their own lines, so you can see what the leak cost. We schedule the units with active leaks and the stacks with the worst damage first. When the water is coming from a part of the building we do not repair, such as the roof membrane, we say so and give you the photos.
Get a written quote for this job
Three photos and a sentence is enough: a reply within one business day, or ask for a free in-home estimate. Or text the photos to 763-204-2099.
What you supply
- A list of units that report leaks, with dates and the weather if you know it
- Access to those units and the unit above, with notice to residents
- Access to balconies, the roof edge or attic above the leaking stack when needed
- Any past repair records on those windows
What JMB supplies
- A walk of the leaking stacks, inside and out, with a water test
- A written finding per opening: window, flashing, wall above or not window-related
- Pull and reinstall on a sill pan with new flashing tape, or new sealant, or a new window
- Interior drywall and trim repair at each opening, quoted as its own line
- Photos of each opening open, flashed and closed
- Each opening closed the same day
- Painting quoted as a separate line, or left primed for your painter
How it is priced: per opening
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Where the water comes in: sealant joint, head flashing, sill, mull joint, or the wall above
- Reseal in place vs. pull and reinstall vs. a new window
- Siding, brick or stucco around the opening that has to be cut and patched
- Water damage to sheathing, framing, drywall or trim
- Floor height and access to the outside of the opening
- How many openings on the same stack or elevation show the same failure
Send a list of leaking units, a photo of each stain inside, and a photo of the outside of that window and the wall above it.
How long it takes
Tracing a stack takes a visit with a water test. Most reseals and pull-and-reinstalls are done in a day per opening; drywall repair needs return visits for mud to dry.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized reply within one business day. Prefer a look in person? A free in-home estimate is always an option.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Reseal in place
When the frame and flashing are sound and only the exterior sealant joint has failed. The cheapest fix, and only when the water test points there.
Pull and reflash
The window comes out, the rough opening is checked for rot, a sill pan and new flashing tape go in, and the same window is reinstalled. For sound windows set without a pan or with failed flashing.
Replace the window
When the frame is cracked, the corner joints have opened, or the window is past saving. The new unit goes in on a pan with flashing, priced per opening.
Not the window
When the water comes from a balcony, the siding or the roof edge above, we document it with photos and tell you which trade it is.
Apartment Window Leak Repair — Find the Source, Then Fix It: questions, answered
Why is water leaking below the window in my apartment building?
Either the window or its flashing is letting water in, or water from higher on the wall is running down behind the siding and showing up at the window. Balconies, siding joints, a window one floor up and the roof edge are common sources. A water test from the bottom of the opening up tells which one it is.
Do you need to replace a leaking apartment window?
Often not. Many leaks are a failed sealant joint or a window set without a sill pan, and pulling the window and reinstalling it on a pan with new flashing fixes it. We replace the window when the frame or its corners have failed. The quote lists which fix each opening gets.
Which units should be fixed first?
Units with active leaks, then the stacks where the damage inside is worst, then openings on the same elevation that show the same failure. We schedule in that order so the water damage stops growing while the rest of the building waits its turn.
Do you repair the drywall under a leaking apartment window?
Yes, as its own line on the quote. Wet drywall is cut out back to dry material, the framing behind it is checked, and the patch is taped, mudded and primed. Painting is quoted separately, or left for your painter.
What if the leak is not the window?
We say so, in writing, with photos of where the water enters. If it is siding, trim or flashing around the opening, we can usually fix it in the same visit. If it is the roof membrane or a balcony waterproofing system, we tell you which trade to call.
Can an insurance claim cover water damage from a window leak?
That depends on the policy and on what caused the leak, so check your policy and ask your agent. The owner or association files the claim and deals with the insurer. We document the damage with photos and line items, meet the adjuster if asked, and do the repair.
Recent JMB work, from our job log
59 installs recorded across 30 Twin Cities communities since Dec 2025. Window and door installs for homeowners and the builders we work with. Counts come straight from our job log; no customer names.
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Read morePage reviewed October 9, 2026 · JMB Builders LLC, MN license BC809005 · All apartment buildings pages
Where we work
Apartment & Multifamily Window and Door Projects near you
Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: