Window Leaking When It Rains — Leak Found, Flashing Fixed
Water on the stool after a storm, stains on the drywall under the window, or a drip from the head. We find the path and close it.
When a window is leaking when it rains, JMB Builders finds where the water gets in before fixing anything, across the Twin Cities metro. We water-test the window, open the trim where needed, and trace it to failed caulk, missing head flashing, no sill pan, blocked weeps or a bad mull joint. Then we reseal, reflash, reinstall the window, or replace it. Priced per window, quoted from photos.
- Priced per window
- Water test before any repair
- Reseal, reflash, reinstall or replace
- Licensed MN contractor BC809005
A window leak is almost never the glass. Water gets in at the edges: past a caulk joint that cracked, behind siding with no head flashing above the window, over a sill with no pan to catch it, through weep holes packed with dirt, or at the joint where two windows are mulled together. The stain inside is often a foot away from where the water enters.
Guessing is how people caulk the same window three times. We run water on the window from the bottom up, one section at a time, and watch inside. If it does not show, we pull interior trim or a piece of siding to see the wall. Once the path is found, the fix matches it: new sealant, a flashing repair, a reinstall of the same window in a proper sill pan, or a new window when the unit itself is failing.
What you supply
- Photos of the stain or water inside and the window from outside
- When it leaks: every rain, only wind-driven rain, or only with snow melt
- Access to the room and the outside wall, including a hose bib
What JMB supplies
- Water test of the window, bottom to top, to find the entry point
- Trim or siding opened where needed to see the wall
- Sealant, flashing tape, head flashing, drip cap or sill pan as the fix calls for
- Reinstall of the existing window in a sill pan when the install is the problem
- Replacement window when the unit itself is failing (quoted separately)
- Photos of what we found and what we fixed in your job folder
How it is priced: per window
Quoted in writing from your photos within one business day. What moves the number:
- Where the water enters: caulk, head flashing, sill, weeps or mull joint
- Siding type around the window: lap, stucco, brick or cedar
- Pull and reinstall of the same window vs. a new window
- Water damage to sheathing, framing, drywall or trim inside
- Second-story access
- Whether the leak repeats on several windows on the same wall
Tell us which rains make it leak and send a photo of the outside wall above the window. Wind-driven leaks point to different causes than steady ones.
How long it takes
Finding the leak and resealing or reflashing: a few hours per window. Pulling and reinstalling a window in a sill pan: half a day. Interior drywall or trim repair may be a second visit.
How your project works
- 1
Photos and history
Send photos inside and outside and tell us when it leaks. You get a written quote within one business day for the diagnosis and likely repair.
- 2
Water test
Hose on the window from the bottom up, section by section, with someone watching inside. That tells us where the water gets in.
- 3
Open and confirm
If the test is not clear, interior trim or a piece of siding comes off so we can see the wall and the flashing.
- 4
Repair
Reseal, reflash, reinstall the window in a sill pan, or replace it. Then the water test again to prove it is dry.
Situations and options
Failed caulk or sealant
The joint between window and siding cracked or pulled away. Old sealant cut out, backer rod where the gap is deep, new sealant. The quickest fix, and often not the whole story.
Missing head flashing or drip cap
Water running down the wall gets behind the trim above the window. Siding or trim comes off, flashing goes in lapped under the wrap, and it is put back.
No sill pan
Water that gets past the frame has nowhere to drain and soaks into the wall under the window. The window comes out, a sloped pan goes in, and the same window is reinstalled.
Window Leaking When It Rains — Leak Found, Flashing Fixed: questions, answered
Why is my window leaking when it rains?
Most window leaks come from the edges, not the glass: cracked caulk, missing flashing over the head, no sill pan under the window, blocked weep holes, or a failed joint between two mulled windows. Wind-driven rain finds gaps steady rain does not. A water test finds the actual entry point.
Why is my new window leaking?
A new window that leaks almost always has an installation problem: no sill pan, flashing tape lapped the wrong way, or the window set without tying it into the housewrap. The window itself is rarely the cause. The fix is usually to pull it and reinstall it correctly.
Can a leaking window be fixed without replacing it?
Usually, yes. If the window unit is sound, the fix is resealing, adding flashing, or pulling it and reinstalling it in a sill pan. Replacement makes sense when the frame is rotted or the unit itself is failing.
Water is coming in at the top of my window — what is it?
Water at the head usually comes from above: missing or failed head flashing, a missing drip cap, or water behind the siding from higher up the wall. The window gets blamed because that is where it shows. We check the wall above before touching the window.
Will caulking stop my window from leaking?
Sometimes, if the only problem is a cracked joint. Often caulk just moves the leak or traps water inside the wall. We find where the water enters before sealing anything.
Do you fix the water damage inside too?
Yes. Wet sheathing, framing, drywall and trim are repaired once the leak is fixed. The inside repair is quoted separately after we see how far the water went.
Why is ice dam water coming in around my window?
Snow melts on the warm part of the roof, refreezes at the cold eave and backs water up under the shingles. That water runs down inside the wall and comes out at the first opening it finds, often the top of a window below the eave. The window is not the cause. The fix is at the roof and attic: air sealing, insulation and venting, plus ice and water shield at the eave. We repair the wet trim and drywall at the window once the source is dealt with.
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 for the builders and dealers we sub for. Counts come straight from our job log; no customer names.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
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Read morePage reviewed September 26, 2026 · JMB Builders LLC, MN license BC809005 · All windows pages
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