Window Replacement Terms Explained: A Plain-English Glossary
If you are reading window quotes and running into words like "full-frame" or "low-E" for the first time, this window replacement glossary is for you. It explains the terms Minneapolis homeowners actually meet when they compare bids, talk to a window installer, or plan a basement project. Use it to read a quote line by line, ask better questions, and spot vague answers before you sign anything. Every definition here stands on its own, so you can skim to the term you need.
- Insert Replacement: new window inside the old frame
- Full-Frame Replacement: everything comes out, down to the studs
- Double-Hung Window: both sashes slide up and down
- Casement Window: cranks open like a door
- Sash: the part of the window that holds the glass
- Rough Opening: the framed hole in the wall
- Low-E Glass: a coating that blocks heat transfer
- Insulated Glass Unit (IGU): sealed double or triple panes
- U-Factor: how well a window holds heat in
- Egress Window: a window big enough to escape through
- Window Well: the dug-out pit around a basement window
- Bedroom Egress Requirement: the code rule for basement bedrooms
- Glass Block: solid glass units mortared in place
- Flashing: the layer that sheds water away from the window
- Capping: metal trim covering exterior wood
- Free Quote: a written price with no obligation
Window Replacement Methods and Glossary Terms
These terms describe how the work gets done, and they drive more of the cost than the glass itself. This is the part of a window replacement glossary worth reading twice, because "replacement" can mean two different jobs.
Insert Replacement
An insert replacement is a new window installed inside your existing window frame, which stays in the wall. The old sashes and hardware come out, but the original frame, trim, and siding stay put. It costs less and goes faster, but you lose a little glass area and you are trusting the old frame to be square and rot-free. If an installer quotes an insert without checking the frame for rot, ask why.
Full-Frame Replacement
A full-frame replacement means the entire old window comes out, frame and all, down to the rough opening in the wall. The installer can then fix hidden rot, re-insulate the gap, and flash the opening properly before the new window goes in. It costs more than an insert, but it is the right call when frames are rotted, warped, or leaking. In older Minneapolis homes, full-frame work is common because decades of weather take a toll on wood frames.
Double-Hung Window
A double-hung window has two sashes that both slide up and down in the same frame. It is the classic style on most Minneapolis homes, and most sashes tilt in so you can clean the outside glass from inside. Because it is so common, double-hung replacement windows come in a wide range of sizes and prices. If your quote lists "DH," this is what it means.
Casement Window
A casement window is hinged on one side and cranks open outward like a small door. Casements seal tighter than sliding styles because the sash presses into the frame when closed, which helps in a cold climate. They are a frequent pick for basements and over kitchen sinks where reaching up to slide a sash is awkward. The crank hardware is the part that wears out, so ask what the hardware warranty covers.
Parts of a Window and Window Replacement Components
Quotes often name window parts without explaining them. Here is what the words on the page refer to.
Sash
A sash is the frame that holds the glass and moves when you open the window. In a double-hung window there are two sashes; in a casement there is one. Some problems, like a broken seal or a stuck sash, can be fixed by replacing just the sash instead of the whole window. Knowing the word lets you ask whether a cheaper sash-only fix makes sense.
Rough Opening
A rough opening is the framed hole in the wall that a window fits into, measured before any trim goes on. Installers measure it to order the right window size, and a bad measurement is the most common cause of delays. In a full-frame job, the crew works directly in the rough opening, so they can see and fix water damage. If a bid mentions "RO dimensions," this is what it means.
Low-E Glass
Low-E glass is window glass with a thin invisible coating that reflects heat while letting light through. In a Minneapolis winter, it reflects your furnace heat back into the room instead of letting it escape through the glass. Nearly all new replacement windows include it, so treat it as standard, not an upgrade worth a big surcharge. Ask which surfaces carry the coating if you want to compare bids closely.
Insulated Glass Unit (IGU)
An insulated glass unit is two or three panes of glass sealed together with an insulating gas, usually argon, in the space between. When you hear "double-pane" or "triple-pane," this is the part being described. If the seal fails, fog forms between the panes and cannot be wiped away, which is a common reason homeowners call about window replacement in the first place. Triple-pane costs more and insulates better, which matters most on north-facing walls in cold climates.
U-Factor
U-factor is a number that measures how much heat passes through a whole window; lower numbers mean better insulation. It is the single most useful number for comparing windows in a cold climate like Minneapolis. Look for it on the window's rating label and in your quote. If two bids list different U-factors, you are not comparing the same window.
Basement and Egress Terms
Basement window work has its own vocabulary, and it is where safety rules enter the picture. For the full picture on whole-house work, see our page on window replacement in Minneapolis.
Egress Window
An egress window is a basement window large enough for a person to climb out of in an emergency, and for a firefighter in gear to climb in. Building codes set minimum opening sizes, and a normal small basement window usually does not meet them. Installing one often means cutting the foundation wall larger, which is why egress work costs more than a simple basement window replacement. If you plan a basement bedroom, this term will come up early.
Window Well
A window well is the dug-out, walled pit outside a below-grade basement window that holds back the soil and lets in light. Egress window wells must be large enough to stand in and may need a built-in ladder or steps, depending on depth. Materials matter here; galvanized steel wells resist rust and hold up against Minneapolis frost cycles. A quote for window well installation should say what material and size you are getting.
Bedroom Egress Requirement
The bedroom egress requirement is the code rule that every sleeping room must have an escape route to the outside, usually a window of a minimum size. It is the reason a finished basement bedroom needs a true egress window, not just any window. Skipping it risks failed inspections, insurance problems, and a room you cannot legally call a bedroom when you sell. Check your local code, or ask a local installer who handles egress work to walk you through what your opening needs.
Glass Block
Glass block is a window made of thick, hollow glass units mortared together like bricks. Block windows let in light while blocking visibility, and they are tough against break-ins and weather, which makes them popular for basement windows that do not need to open. They do not count as egress, so never use glass block where a bedroom escape window is required. They are a good fit for laundry rooms and utility areas.
Paperwork, Water, and the Fine Print
These terms show up in contracts and on the exterior work. They decide whether the job holds up over time.
Flashing
Flashing is the layer of metal or waterproof material installed around a window to steer water away from the opening. Bad or missing flashing is the top cause of rot and leaks after an installation, and you cannot see it once the trim goes on. Ask any bidder to describe how they flash an opening; a clear answer is a good sign. Full-frame jobs give the crew the access to do this right.
Capping
Capping means wrapping the exterior wood trim around a window in bent aluminum so it never needs paint. It protects the trim from rain and snow and gives the outside a clean finish. Some quotes include capping and some leave it out, which can explain a price gap between two bids. Ask whether capping is included before you compare numbers.
Free Quote
A free quote is a written estimate for your project that costs you nothing and commits you to nothing. A useful one lists each window, the installation method, the materials, and what happens to the old units, not just a single total. Pricing varies by project, so a real quote requires someone to measure your actual openings. If a company prices your whole house over the phone without seeing it, treat that number as a guess.
Using These Window Replacement Glossary Terms
What this window replacement glossary gives you is the ability to read a quote line by line and know what each charge buys. You can now ask whether a bid is insert or full-frame, what the U-factor is, and whether capping and flashing are included. Those questions take minutes to ask and tell you fast which installer knows your house.
If you need basement egress window installation, Minneapolis Window Pros can help.
Prefer to talk it through? Call (612) 482-9787 — a quick call is usually the fastest way to get a straight answer for your situation.