Plastic surgeons talk about a tuck here, a lift there to improve an aging face. Architects and contractors talk about a doorway here, a window there, areas where a few changes can renew the looks of an aging structure.

An older house often shows the ravages of time and weather, including warped wood and rusted or pitted metal frames and fittings. Owners may find themselves forcing metal casement windows shut or worrying over leaks that trickle in where wood sashes don't quite meet wood sills.

The windows on Jochen and Huda Kraske's 1940s brick rambler in Bethesda had a habit of freezing not quite shut. When the Kraskes built an addition to the house, with the help of architect Harry Montague, they decided to install double-glazed Pella casement windows throughout. Contractor Joel Truitt of Truitt and Associates reported that the company was especially cooperative, and "even specially milled wood to cover a corner support beam between two windows."

Pella is one of the leading, if not the most expensive, window makers; its products seem to carry a certain cachet -- new owners have been known to leave the labels on for all the neighbors to see long after construction is completed. That company, and a handful of others, have taken window design to new heights. There are insulated windows with adjustable venetian blinds built into the air space between the two panes (no more dusting); double-glazed windows with a removable interior pane so you can clean the inside of the windows and not worry about the leaky seals on thermopane glass; whole windows that can be removed from the inside, making cleaning easier; and single-pane windows with plastic grids that give the appearance of a multi-paned window but are quicker to clean. And there is also an increasingly wide selection of new greenhouse windows.

Jonathan and Arlinka Blair, with the help of designer John Christian, decided to do something dramatic with their classic brick row house in the District. To bring more light into the house, they first set about replacing windows. Upstairs, the conventional double-hung variety were replaced with tall windows extending the original opening. The upper part of the window is stationary; the lower part can be opened. Downstairs, the first floor was brightened with a 4-by-8 foot span of Pella casement windows. The Blairs added a porch as well as a wood facade to replace the old mansard roof front, and had the exterior stuccoed.

Other ideas for revamping a house by changing the windows: knock out a double-hung window and install a glass door that opens to a deck or back yard; replace side by side double-hung windows with a bay window, or replace a picture window with a smaller, stationary window and casements on either side.

Or take a tip from an owner who made his ordinary brick rambler more elegant by removing the old casement windows and cutting the window opening to the floor. Small awning windows (18 inches from the floor up) hinged at the bottom open to provide cross-ventilation. The rest of the window is stationary.