Heritage districts and design review
Plano's locally designated districts include Haggard Park (designated 1999) and Downtown (designated 2002), each with its own design standards. The city's Heritage Preservation Ordinance, as set out in an unofficial consolidated copy dated September 1, 2021, requires a Certificate of Appropriateness for repair other than maintenance, for alteration, and for material changes to doors, windows, woodwork and other exterior elements visible from a public right-of-way. The certificate comes before any building permit. Maintenance and minor in-kind repair, such as touch-up painting or a new windowpane, are not blocked. Whether a given exterior job is maintenance, minor in-kind repair, or a material change that needs a Certificate of Appropriateness is for the city to decide; ask the Heritage Preservation Officer before work starts.
Texas notice and clearance
Texas rule 25 TAC 295.214 puts the paperwork on the contractor: the certified lead firm must give DSHS and the regional office written notice no less than seven working days ahead of the abatement start date, with a separate notice for each building. The household lives elsewhere while work is under way. When it ends, a certified inspector or risk assessor performs a clearance check, and that report goes in the house file next to the original test results.
For sound plaster and trim you would rather keep, see lead paint encapsulation. If original windows are beyond saving, lead-safe window and door replacement explains the alternative.