b'If the special shape is ordered to be installed alone, Using a hair dryer to warm the vinyl, this extensionthen modified, conventional framing methods needsystem can be bent to accommodate curved windowsto be used. as well.Because of the variety of shapes that are possible, 1. Special shapes, whether mulled or separate, muststandardized instructions are not really possible,be installed in a clear opening with the old windowor practical to follow. (sash and frame) completely removed.Circular windows are braced differently than oval 2. Integral fin should be used on special shapes as awindows, and angular windows are braceda third nailing anchor and to create a self-flashing installa-way. In fact, the only basic, common feature with tion.special shapes is the need for jamb extensions to3. All windows, rectangular, curved, or otherwisefit them to the interior wall.require a proper sized header above the window toIf these extensions must be cut from wallboardsupport the studs above. or wood it will require more skill than most4. All odd-shaped windows require similar studdingamateurs have.to a conventional rectangular window opening.The good news is that some manufacturers make 5. A Drip Cap, formed by shaping aluminum or vinyl pre-formed jamb extensions that snap-in to the J-channel (fan-cut for curved windows) should begroove provided for the snap-in mull strips.installed above all windows over proper flashing.Flashing Curved WindowsStep 1 Take care that the Step 3 Place the window insheathing is applied the opening. Nail justwith the correct arc enough to anchor it toand that the proper the opening, but notsupport for the curved too much to deformwindow is in place.the nailing fin andToo often it is cut or allow the window toformed haphazardly slightly expand andand the resulting gaps contract.invite leaks no matter Do not nail across thehow well the opening bottom.is flashed.Step 2 Just as you wouldStep 4 Cut three pieces ofin a rectangularflashing and applyopening, the sillthem in overlappingflashing is applied sequence over theacross the bottom nailing flange.and slightly up the Apply top piece last.sides. Make sure itextends past theUse flexible uPVC sides of the opening. or carefully notch Place a bead of bed- aluminum to make ading sealant on thedrip cap if needed.sheathing or behindthe nailing flange. Caulk across the bottom leaving twogaps for drainage.Window Fitters Guide to Window Installation952020 AWDI, LLC Do not reproduce without permission'