1. Measure and quote
The installer measures every opening, usually inside and out, checks the frames and sills for rot and confirms which openings are bedrooms. The written quote should list each window by location, the product series, the U-factor and SHGC, whether it is an insert or full-frame, trim and disposal, and who handles any permit.
2. Paperwork before work
- License. In Knox County, a residential job of $3,000 to $24,999 requires a Tennessee Home Improvement license; $25,000 or more requires a contractor license from the Board for Licensing Contractors.
- Cancellation. If you sign at home, the FTC Cooling-Off Rule generally gives you three business days to cancel a sale of $25 or more.
- Permit. Changing an opening's size, cutting a new opening or adding a bay needs a permit. For same-size swaps, confirm with the City of Knoxville, Knox County Codes Administration or your town's codes office.
- Historic overlay. In an H-1 district a Certificate of Appropriateness comes before the permit.
3. Order and lead time
Replacement windows are made to size, so there is a gap between signing and install. Custom shapes, colors and large units take longer. Ask for the expected install window in writing.
4. Removal and prep
For an insert, the old sashes, stops and parting beads come out and the old frame stays. For full-frame, everything comes out to the rough opening. On a pre-1978 house, EPA lead rules cover window replacement no matter how little paint gets disturbed, so the firm must be RRP certified and use containment.
5. Setting and flashing
Knoxville averages just under 52 inches of rain a year, so the flashing details are where good and poor installs part ways:
- A sloped sill pan or flashing under the window, so any water that gets in drains out.
- Flashing tape lapped shingle-style: sill first, then sides, then head.
- Shims at the right points so the frame is plumb, level and square, without bowing.
- Low-expansion foam or backer rod and sealant in the gap, not standard expanding foam that can bow the frame.
- Exterior sealant where the frame meets brick or trim, leaving weep paths open.
6. Finish and inspection
Interior trim goes back or new trim is installed, and the sash is adjusted to lock and slide smoothly. If a permit was pulled, the inspector checks the work. Leave the NFRC labels on the glass until then so the ratings can be confirmed. Keep the paperwork: product series, warranty registration and the permit card.
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