Double-hung or single-hung?
In a double-hung both sashes move. In a single-hung only the bottom one does and the top is fixed. Double-hung costs more but lets you drop the top sash to vent warm air out near the ceiling, which helps on humid evenings, and both sashes usually tilt in so you can clean the outside glass from indoors. That matters on a second floor in a two-story colonial.
Matching the look of older houses
Knoxville has the largest concentration of homes in the country designed by George Franklin Barber, and the late-1800s streetcar suburbs around Fourth and Gill, Parkridge and Fort Sanders are full of tall, narrow double-hungs. The 1920s and 1930s houses of Sequoyah Hills and Lindbergh Forest mix double-hungs with casements. When replacing in these neighborhoods:
- Keep the original sash proportions. A thick replacement frame shrinks the glass noticeably on a narrow opening.
- Simulated divided lites (grids bonded to both sides of the glass) read far better from the street than grids between the panes.
- Inside an H-1 historic overlay or NC-1 conservation district, check with the Historic Zoning Commission first. A Certificate of Appropriateness is required before a permit can be issued for exterior work, and guidelines favor repairing original wood windows.
Insert or full-frame
An insert keeps the old frame and slides a new frame-and-sash unit inside it, after the old sashes, stops and weights are removed. It is quicker and leaves interior trim alone, but you lose some glass area. A full-frame replacement strips the opening to the rough framing, which allows sill rot to be repaired and the opening flashed properly. On older homes where the sill is soft or the frame is out of square, full-frame is usually the better call.
Old sash-weight pockets are empty cavities in the wall. Ask the installer whether they will insulate them during an insert job.
Bedroom egress
A double-hung opens only half its height, so on a bedroom window the clear opening can be smaller than you expect. The 2018 IRC lets a replacement window skip current egress sizing if it is the manufacturer's largest standard size that fits the existing opening and is the same operating style. If you change styles or enlarge the opening, current rules apply: 5.7 sq ft net clear (5.0 for a grade-floor room), 24 inches of clear height, 20 inches of clear width and a sill at 44 inches or lower. A casement meets those numbers in a smaller opening; see casement windows.
Cost
| Type | National installed range, per window (Fixr) |
|---|---|
| Single-hung | $250–$700 |
| Double-hung | $300–$1,000 |
| Vinyl frame, any style | $350–$800 |
| Wood frame, any style | $600–$2,000 |
These are national ranges, not Knoxville quotes. For a full picture of what moves the price, see the cost guide.
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