Above each porch is a triple-sash window.

Triple-sash windows open onto the porch, permitting passage from the porch to the center parlor.

Restoration efforts have simplified Monticello's decorating schemes - erasing the pompons and gilt trims from its wide-paned, triple-sash windows.

Radiators were mounted on the walls to prevent dust from collecting underneath; flooring material was curved up to the walls; and the unusual triple-sash windows, extending all the way to the floor and leading out to the extensive balcony system, provided more than the usual interior ventilation.

On the second floor, Ms. Van Lengen can throw open the window sash - one of Jefferson's famous triple-sash windows, which can be used as doors - to stroll across rooftop walkways that Jefferson designed so that professors could confer without mingling with students on the Lawn.