How to Measure for Window Replacement
The Ins and Outs of Vinyl Window Replacement
By Matt Weber
Windows take a lot of weather abuse, and their material makes a significant difference in durability and performance.
Wood windows generally require repainting and re-glazing every 2-3 years, which can be drag on a homeowner’s time and patience—or their wallet if they hire a painter.
Although painted aluminum windows can pit, they don’t generally have the same maintenance problems as wood. However, aluminum windows are notorious for poor thermal performance. Much like radiators they conduct unwanted heat from the outside into the room. In the winter, aluminum transfers cold in the same way. This heat transfer creates condensation and related problems. Many modern aluminum windows now utilize “thermal breaks” to address the condensation issue and increase energy efficiency. These “breaks” are made of vinyl.
Vinyl replacement windows are a top choice for home remodeling because vinyl is itself a thermal break, minimizing heat transfer from the outside the home to the inside. Vinyl windows look great, are energy efficient and require very little maintenance. There’s also no need to repaint or restain vinyl windows, since they are the same color throughout.
However, before placing an order for a replacement window, the first critical step is to determine the right measurement for the new window.
How to Measure for Replacements
The simplest method of replacement is to swap the existing window for a new unit of the same size. This is called a pocket replacement and allows the homeowner to keep the trim intact around the windows. Depending on the construction of your windows, it may help to remove the old interior trim to ensure correct measurements of the rough opening. If the window manufacturer offers specific measuring instructions for their particular windows, defer to those guidelines.
When measuring the existing window for width, place the tape against the jamb and measure to the other jamb (not the stop molding or the parting bead, which are wooden strips attached over the jamb). On double-hung windows, the parting bead that separates the sashes will be removed from the jamb when the new windows are installed. Replacement windows are sold in a standard thickness to fit inside the 3-1/4-in. pocket that exists between the outside and inside stops after the parting bead is removed.
Measure the window’s width in three places—top, middle and bottom of the window. Use the smallest of the measurements to determine the width that surrounds the window.
Next, measure the height of the window, placing the tape on the very top of the sill. The sill is not to be confused with the window stool, which is a piece of interior molding at the bottom of the window to give it a finished appearance. On a double-hung window, the sill is the board the sash closes onto. The sill is usually sloped to divert water away from the house, so it is important to strike the measurement from the uppermost point of the sloped sill. Measure from the sill to the top jamb (not a stop or parting bead).
Measure the window’s height in three places—right, center and left of the window. Use the smallest of the measurements to determine the height surrounding the window.