How to Trim Cement Block Windows
- 1). Hold a carpenter's square against one of the window's top corners. Measure 3/16 inches in from the window's side jamb interior edge. Draw a light pencil line down the jamb at this measurement.
- 2). Rotate the carpenter's square and measure 3/16 inches up from the window's top jamb bottom edge and draw a line. Move the carpenter's square to the other top corner and mark the 3/16-inch reveal for the top and side jamb. Do the same in the bottom two corners.
- 3). Measure the length of the top reveal line and transfer this to a piece of window trim. Set a miter saw to a right-hand 45 degree angle cut. Cut the trim on the left mark. Swing the miter saw to a 45 degree left-hand cut and cut through the mark on the right side.
- 4). Position the cut trim piece over the window. Line up the trim's bottom edge with the reveal lines. Hold a level against the trim to check that it is straight. Use a hammer drill and masonry drill bit slightly smaller in diameter than the finishing screws you will be using. Drill three or four pilot holes through the trim piece and into the cement block wall.
- 5). Drive finishing screws through the pilot holes to secure the trim piece in place. Measure the lengths of the right- and left-side window jambs. Make the measurements from the top trim piece's bottom corners to the reveal line on the bottom jamb. Transfer these measurements to trim pieces.
- 6). Position the miter saw to a 45-degree left-hand cut. Cut the right trim piece's top mark and the left trim piece's bottom mark. Turn the miter saw to a 45 degree right-hand cut. Cut the left trim piece's top mark and the right trim piece's bottom mark.
- 7). Place the right trim piece on the window's right side. Line up the inner edge with the reveal line. Hole a level against the trim piece to check that it is straight. Drill three to four pilot holes through the trim piece and into the cement block wall. Secure it in place with the finishing screws. Repeat with the left trim piece on the window's left side.
- 8). Measure the distance from the right trim piece's inside corner to the left trim piece's inside corner and transfer this measurement to a new trim piece.
- 9). Set the miter saw to a right-hand 45 degree angle and cut the trim's mark on the right side. Turn the saw to a left-hand 45 degree cut and cut the mark on the left side.
- 10
Place the bottom trim piece underneath the window. Hold a level against it to check that it is straight. As long as the left and right side trim pieces are straight, this piece should rest firmly and evenly in place. Drill three or four pilot holes through it and secure it in place with finishing screws.
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