b'Details of Proper ShimmingShimming is necessary for almost every window and Two Solutionsdoor installation - mostly because there is no such Plastic, Stackable Shimsthing as a perfectly square and plumb opening. Horseshoe or u shapedShimming allows you to center the window and level shims work perfectly becauseand plumb the window in the opening. the open portion goes overShimming is also one of the more misunderstood, the anchor screw andand/or carelessly attended to steps in installation. because they come in differ-Very few installers bring adequate shimming to the ent thicknesses, and arejob with them and the installation is the worse for it. stackable (small grooves lockThere are two keys to proper shimming them in a pile as more are1. Shims must be between the window unit added), shims can be added and removed as the and the rough opening at each spot where the window is leveled, plumbed and squared.anchor screws are placed, and the screws should Self Shimming Anchors. Developed in Europepass through the shims in order to keep them from these anchors have a collar set just below the head soshifting in the opening, and to ensure that the win- that the anchor snaps into the hollow lineal holdingdow frame is secure and snug to the rough opening the lineals wall between the collar and the head. 2. Shimming must be flat. Using tapered In this way, asshims alone will result in the distorting of the window the anchor isframe which will not only keep the frame from being turned clock-adequately secured to the rough opening, but will wise, the frameprobably cause the distorted frame to either impede is pulled closerthe operation of the window or door unit, or cause to the openingthe precision balances or weatherstripping to fail to wall. work properly or wear out prematurely. When theanchor isturned counter-clockwise, the frame is pulled awayfrom the opening wall. The result is dynamic shim-ming during installation and after.Tapered Shims in Pairs create "level" support With Self Shimming anchors, final adjustments can be made after all trim is added allowing If the window unit is not fitted with factory precision alignment of the locks, interlock and installed butterfly clips or flat plastic shims are not weatherstripping.available, tapered shims are best used in pairs.In Self Shimming anchors can come with plugs forthis method, the first shim is placed fat side in, the use in concrete walls to meet Hurricane Codes.second is slid in thin side first until the pair makes aflat, and snug fit.Then the shim pair is trimmedflush to the outer edge of the window frame.Since windows with fins or replacement windowsfitted against the old window stops prevent shimsfrom passing through to extend on both sides, itbecomes tricky toinstall them properly.With available shimstock, precuts are usually 12 inches long, 1-1/2 wide and taper from 5/16at the fat end to nothing at the other After inserting shim pairs cut offend. the ends flush with window frameWindow Fitters Guide to Window Installation72020 AWDI, LLC Do not reproduce without permission'