Window Fitters Guide to Window Installation 86 ©2022 AWDI, LLC Do not reproduce without permission Frame-Out, Kerfed Brickmold Method for OldMetal Finned Windows with 2-1/4” or 2-3/4” Frame Depth Both old single hung and old aluminum sliders, often installed in a structure with wood or other lapped siding, or even stucco, should be replaced by removing the entire old window down to the rough opening. As shown in the figure at right, the old wood window is anchored to the structure by nails through the brick mould casing. The old aluminum window is anchored by nailing through the fin, and then having the fin covered by the siding or wood casing. Using a new construction vinyl window (with an integral nailing fin), this alternative method of installation makes use of a wood block (preferably cedar), typically 1-1/2” by 1-1/2” however, any size that makes the job work well is what to choose. This block is attached to the integral nailing fin around the perimeter of the vinyl window frame. This block, in essence, replaces the brick mould casing of the old wood window, or the nailing fin and wood casing of the old aluminum window. Care needs to be taken to make sure that the new window with the cedar blocking fills the same opening dimensions of the old window that is removed. If necessary, cut back the siding for a more perfect fit, but if there is sufficient room, accurate measurement prior to ordering the replacement vinyl window may avoid cutting back any siding. It is also important to make sure that there is a proper drip cap along the header of the vinyl window with the blocking and that the entire perime- ter of the new installation is properly caulked to avoid water penetration. Installations using the rough framing can be done from either the inside or the outside of the home, but the blocking method must be done from the exterior. Cut back the siding to install the blocked window. 1. Draw a line on the siding, 1-1/2” from the edge of the rough opening at the head, sill and both jambs. This will be the edge that the blocking will butt up against. 2. Use a circular saw or Window Fitter oscillating tool to cut along the line (to cut through the siding, but not the sheathing or studs below the sheathing) and remove the siding pieces within the cut. Under some circumstances, the existing window could have been removed. If the existing window is still in place, and there is no casing covering the window nailing fin, removal of 1-1/2” of siding should expose the nailing fin of the old window allowing it to be removed. 3. Measure the depth of the rough opening pocket from the edge of the interior trim (extension jambs or drywall return) to the outside edge of the wall substrate (sheathing or similar) against which the blocking will be seated. The common measurement will be between 3/4” to 1”. Whatever the dimension, it is the measurement that will determine the location of the slot to be cut in the blocking. Care always needs to be taken to avoid damaging the weather barrier under the old siding. Prying out old windows can damage the building paper and substrate. These methods allow proper removal of the old window and proper installation and re-establishment of the weather barrier avoiding leaks and potential moisture damage under the siding. Brickmold Casing Old Single Hung Window Old Aluminum Window Exterior Wood Casing Nailing Fin SAMPLE MANUAL
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