Clerestory Window Replacement — High Glass Above a Lower Roof
The high windows that light the room from above are fogged, leaking a stain down the wall, or turning the loft into an oven every summer afternoon.
Reply within one business day. Or call / text 763-204-2099.
Clerestory window replacement means the row of high windows near the ceiling, often in a wall that rises above a lower roof. JMB Builders reaches them from inside staging and roof brackets or a lift, checks the roof-to-wall flashing below them, picks fixed or venting units and glass for the sun, and installs them across the Twin Cities metro. Priced per opening; photo reply within one business day, or a free in-home estimate.
- Priced per opening, windows supplied
- Roof-to-wall flashing checked below the sills
- Fixed or venting, glass picked for the sun
Clerestory windows sit high in a wall, close to the ceiling, to bring light deep into a room without giving up wall space or privacy. On many contemporary and split-roof houses they sit in a short wall that rises above a lower roof, so the bottom of each window is only a foot or two above shingles. That makes two problems: they are hard to reach, and water running down the upper wall meets the lower roof right under the sills.
When a clerestory leaks, the window is not always the cause. The flashing where the lower roof meets the wall below the windows fails often, and the stain shows up at the same spot. We look at both at the measure. If the step or apron flashing is part of the leak, it is redone while the windows are out, and it shows on the quote as its own line.
The other decisions are fixed or venting and the glass. Fixed units cost less and seal best. A venting unit up high lets hot air out of a loft or vaulted room, opened by a pole crank or, on some lines, a powered operator. Glass with a stronger low-e coating cuts the heat and fading from high sun.
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
- Photos of the windows from inside and outside, including the roof below them
- Where any stain or drip shows up inside
- Fixed or venting, and how you would like to open a high window
- Frame color and glass choice, or ask us to bring samples
What JMB supplies
- One in-person measure of every opening, from staging or a ladder, before ordering
- All the clerestory windows on one order so frames and glass match
- Inside rolling scaffold on protected floors; roof brackets, planks or a lift outside
- Old units out, openings checked for rot, new units set, foamed and flashed
- Step or apron flashing at the lower roof redone where it is part of the leak (its own line)
- Interior trim or drywall returns, exterior capping or trim
- Painting quoted as a separate line — or leave it primed and caulked and paint it yourself
- Haul-away and photos in your job folder
How it is priced: per opening
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Height and access: inside staging, roof brackets over a lower roof, or a lift
- Number of openings in the row and their size
- Fixed vs. venting units, and pole-crank or powered operation
- Glass package for a south or west wall
- Roof-to-wall flashing or shingles to rework below the sills
- Rot at the sills or in the wall below a long-standing leak
Send one photo from outside that shows the roof under the windows, and one from inside with the whole row in frame.
How long it takes
A row of three to five clerestory windows: one to two days, mostly setting up access. Lead time depends on the brand and is written on the quote.
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
All fixed
The simplest and tightest choice when the room already has opening windows lower down. Nothing to reach or adjust later.
Venting units at the ends
One or two units in the row that open to let hot air out of a loft or vaulted ceiling, the rest fixed to keep the cost down.
Sun-control glass
A stronger low-e coating, or tinted glass, on a south or west row that heats the room or fades floors in the afternoon.
Flashing redone with the windows
The roof-to-wall flashing under the sills is replaced while the old windows are out, so the leak is fixed at its source.
Clerestory Window Replacement — High Glass Above a Lower Roof: questions, answered
Why are my clerestory windows leaking?
Either the window seal has failed or water is getting in below it, where the lower roof meets the wall. Rain running down the upper wall lands on that joint, and worn step or apron flashing lets it into the wall. The stain looks the same inside either way, so we check both at the measure.
How do you replace windows that high up?
Inside, a rolling scaffold on protected floors. Outside, roof brackets and planks on the lower roof, ladders, or a lift where the yard allows. The windows are set from both sides at once, and the setup comes down when the job is done.
Should clerestory windows open?
Only if you need the air. A venting unit up high lets hot air escape from a loft or vaulted room, which can help in summer. Fixed units cost less and seal tighter. A common middle ground is venting units at the ends of the row and fixed glass in between.
How do you open a window near the ceiling?
With a crank pole that hooks onto the operator, or on some window lines a powered operator on a switch or remote. A powered operator needs a power source at the window, run by a licensed electrician. We confirm what the line you pick offers before the quote is final.
Why are my high windows foggy between the panes?
The seal around the insulated glass has failed and moist air got between the panes. High windows take the most sun and heat, which works the seal hardest. When several in a row are fogging, replacing the row together usually makes more sense than chasing one at a time.
Can new glass keep a loft from overheating?
It helps. A low-e coating built for sun control blocks much of the heat that comes through high south and west glass, and it cuts fading on floors and furniture. Venting one or two units lets the hot air that collects at the ceiling out.
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 windows pages
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