Start with conditions, not a product
Sill condition against Durham's rolling watersheds, flashing detail, and how the new frame meets older brick or clapboard shape the result more than the glass package does.
Build a complete scope
- Whether the property carries a local historic designation, checked by address
- Whether original sash is repairable rather than replaced
- Each opening measured, since older districts rarely use standard sizes
- Frame and glazing chosen for humid summers rather than northern winters
- Trim restoration, debris disposal, and the warranty on labor and units
Durham context
Which Durham a house sits in decides this job more than any product comparison. In the nineteenth-century districts and the early streetcar neighborhoods, original wood sash is frequently repairable, openings are rarely standard sizes, and paint layers in housing of that age may be lead-bearing, all of which can change the recommendation before a replacement is priced. Postwar ranches generally carry aluminum or early insulated units whose frames, not glass, are the weak point. The suburban edges are a maintenance question rather than a replacement one. What the local climate contributes is specific: humid summers make solar heat gain and the air sealing at the installation more consequential than insulating value, which reverses the advice written for colder regions, and mature canopy means shaded elevations stay wet long enough that flashing detail decides how the opening ages.