Patching a torn or damaged screen can take as much time as replacing the entire thing, and usually leaves the patched-up area obvious. However, with just a few tools, you can remove the old mesh put in an entirely new screen. Then you can replace the screen in the window or door, where it can get back to blocking bugs, looking as good as new.
Step 1 - Remove the Screen From the Window
1.1—Gently take the screen out of the door or window frame and lay it on a flat surface, such as a large table or the floor. Tape each edge down so the frame holding the screen mesh doesn’t move while you work. Be sure to only put tape on the outer edge of the frame without overlapping over the spline groove or the mesh itself.
The mesh is firmly held in place by a pliable rubber tubing —the spline—inserted into a spline groove after the screen mesh. Splines come in a variety of sizes, the most common being the .125"—called 125 thousand of an inch (1/8 inch), the .140" (9/64 inch), and the .210" (7/32 inch). Various sizes and profiles of splines are shown in figure 1.
1.2—Measure the size and the length of the spline needed and also the size of the required mesh to get a repair kit or new individual items—in both cases getting extra length and width to create a necessary overlap of both parts when installing them.
Step 2 - Removing the Screen Mesh
Use an awl or similar pointy device to remove the soft spline tubing from its groove inside the aluminum frame where it firmly holds the mesh in place. The spline can be the full length covering the full perimeter of the frame with the two ends meeting at one spot around the groove, or it can be in four pieces, each running from corner to corner of the screen.
2.1—Either way, remove the old spline by inserting the point of your awl inside the groove and against the end of the spline to apply firm pressure to force the spline out of the groove. If it's too tight inside the groove, tap it lightly with a hammer to force it out.
2.2—Once you get a few inches of the spline out of its groove, grab the end and pull gently on it to keep it from breaking while forcing it out with the awl.
2.3—You can now pull the old screen mesh out of the frame and discard it. Clean out any debris and other broken pieces from the groove and immediate work area.
After a few years of a screen baking in the sun and enduring all sorts of weather, the dried, stiff spline is very likely to come out, breaking into a few (or many) pieces. So careful extraction could save you from having to clean up the groove afterward. If certain areas around the screen profile cause problems while you're removing the spline, check the profile carefully for damage to the frame, which could disrupt the uniformity of the groove's width.
Step 3 - Verifying Your Supplies
3.1—Make sure the spline diameter will fit the groove and that it's long enough to go around.
3.2—Either on a roll or pre-cut, lay the mesh out flat on the screen frame, especially if it's close to the frame's size. Make sure you have an adequate minimum overlap of four or more inches all around the frame.
3.3—The overlapping of the mesh should also be pretty much equally divided over opposite sides to prevent it from pulling on one side while you're rolling it inside the groove. Guide yourself by lining up the threads in the mesh with the edge of the screen frame. This will ensure a uniform and straight installation of the mesh and provide an automatic telltale if the meshing of the screen starts to stretch or pull, losing its square.
The larger the screen, the more critical this is. If the mesh is from a large roll, overlap about four inches over the side—usually the end—where it begins, and unroll the mesh past the opposite side, but without cutting it just yet.
3.4—Double-check your tools. Splines come in various widths, so to execute the perfect professional-looking job, you need your spline roller tool to match the size of your spline.
Roller tools with wheels at each end are better, since each wheel has a particular purpose for meshing (Figure 2). The rounded edge properly inserts the mesh into the groove without damaging it while the concave edge of the other wheel partially wraps around the round spline to keep it from slipping off.
Step 4 - Secure the Mesh to the Screen Profile
4.1—With the mesh properly placed from step 3.3, keep it steady with one hand inside the frame and place the mesh wheel on the roller tool over the groove at the center of a long side. Press down gently to insert the mesh inside the groove (Figure 3). Coaxing it rather than forcing it inside the groove, ride the wheel one way then the other to prevent the mesh from "bagging" or moving over.
Holding the mesh in place forces the mesh from the outside perimeter instead of the inside to slide into the groove and maintain its proper alignment.
4.2—Repeat the same procedure for the opposite side, then the adjacent sides.
4.3—Place the spline on the groove with the end at about 1/8 inch from the corner and push it into the groove with the spline roller tool. (Figure 4a & 4b).
4.4—Roll the spline in right up to the end of the first groove at the corner and shape it into turning the corner with the help of a flat screwdriver (Figure 5). From there, keep rolling it in along the groove of the profile up to the next corner, where you proceed as before and keep going until you reach the start point. As you work along, make sure there are no kinks or folds in the mesh.
4.5—Trim the spline to the right length just short of the corner, and tuck it inside the groove with the screwdriver.
Step 6 - Trim the New Screen Netting
Take the box cutter or utility knife and cut the screen netting along the edge of the frame, just on the outside edge of the plastic spline you just installed. Be sure to cut on the outer edge and not the inner edge, as shown in Figure 6. This will trim away that excess edge of the screen, but the spline will hold the screen in place.
Step 7 - Reinstall the Screen
Replace the screen and screen frame in place, the same as you removed it. It should be as good as new.