HOW TO MEASURE
Ordering requires three measurements: Extension jam width, the finish window surround width and the finish window surround height. Prefabtrim guarantees the measurements you order. The customer assumes the responsibility for proper measurements. Please read, follow and understand proper measuring tips for proper ordering and installation. If you are replacing existing trim, you can measure the existing trim and reuse those measurements for ordering.
Rough opening measurements are optional, however, they are a safeguard to ensure your window surround fits properly. Please remember, in order to do this you must first remove your existing trim unless it is new construction.
Replacing existing surrounds
Finish Window Surround Width and Height
The Finish Window Surround Width Measurement is the inside of the extension jam to the inside of the opposing extension jam. You must determine where the inside of the surround will meet the window. This is called the reveal. Usually a 1/4″ reveal is exposed around the inside of the window. It can be more or less. The reveal is to be determined by the customer. Determine where intersecting reveals meet in all four corners. Mark corners and measure top and bottom. The two measurements should be equal. Refer to picture. Take into consideration handles to open and close window for clearance.
Extension Jam Width
The extension jam is the material which meets the window itself and comes out to the plane of the wall surface. Determine the extension jam width by placing a measuring tape against the edge of the window where the surround will meet the window and read the distance from the window to the plane of the wall. Use a straight edge to assist in the measuring. Measure all four corners and compromise on one common measurement. This is your extension jam width
New Construction Surrounds
Finish Window Surround Width and Height
The Surround measurements are the inside dimensions of the surround. The surrounds jams and/or sill are 3/4″ thick.
NOTE: Your final measurements MUST be 1 1/2″ smaller than your smallest rough opening measurements.
Extension Jam Width
The Surround measurements are the inside dimensions of the surround. The surrounds jams and/or sill are 3/4″ thick.
NOTE: Your final measurements MUST be 1 1/2″ smaller than your smallest rough opening measurements.
Sample Test Piece
Test Trim Piece
Concerned about the measurements? You can order a FREE test trim piece that you can place against your current surround.
All sizes
We offer all sizes of window trim for FREE test pieces