4Step Installation


Temperature and humidity conditions will affect this product and proper precautions must be taken to ensure a quality bond to window frame. 70-90 degree temperature is ideal for the installation of the RWD extender trim. High humidity levels, rain or foggy weather are poor conditions for installation and should be avoided. Winter time conditions pose many challenges for installation of building materials. In cooler temperatures the installer must take precautions and adhere to the following: Once the installer has cut, fit and has dry run for the proper fit onto the window frame it may be necessary for the installer to peel back a small section of the adhesive liner to determine the tackiness of the adhesive. If the adhesive is not tacky to touch, it will be necessary for the installer to apply a small amount of heat to the liner side of the extender trim with a common electrical heat gun. This will soften the adhesive and allow for adequate adhesion.

VERY IMPORTANT: Read #6 for necessary cleaning instructions.
  1. It is very important that all installers understand the physical and chemical characteristics of our double-coated polyethylene foam acrylic PSA tape. The acrylic based tapes feature an aggressive initial tack, but its final high strength bond is achieved in approximately 24 hr.
  2. Properly secure window in opening as per window manufacturers installation instructions with factory sill extender attached and cut back on each side a minimum of ½” or cut back even with beveled projection on mainframe.
  3. Install insulation (optional) around window in wall cavity. NOTE: Be sure insulation is securely behind face of mainframe. Using expandable foam products may cause back pressure on extender trim and should be avoided.
  4. Measure both sides and top separately to determine the correct extender widths and lengths. Allow 1/6” gap on structure side to allow for expansion and contraction. Allow a minimum of 3/4 “ over lap onto mainframe face on interior or exterior meeting edge of factory sill extender. NOTE: For proper adhesion extender must fit without binding at all edges.
  5. Cut extenders to length allowing a little extra for re-cutting for miter or square cut corners. NOTE: Never use an overlapping method when using the RWD extender trim. This will cause an improper adhesion bond and jeopardize the integrity of a watertight seal around the window frame. If needing 2 equal widths simply fold extender trim and separate. The center scoring groove is deep enough without rescoring. Scoring grooves other than the center will need to be rescored with a razor knife to separate trim at that width. Once you have rescored the trim simply fold and separate the pieces.
  6. IMPORTANT: Remove any projecting corner welds. Projecting welds will cause the RWD extender trim to improperly set and lay flat onto the window mainframe. Thoroughly clean mainframe surface with a small amount of Denatured Alcohol or for optimal results, we recommend that the installer use the specially designed individual Isopropyl Alcohol cleaning wipes which can be purchased from RWD Innovative Specialty Trims, LLC. You must allow the alcohol to completely evaporate before applying the RWD extender trim. NOTE: Never use Windex, Mineral Spirits, Lacquer Thinners or Oil Based Thinners to clean the window frame. Any cleaner not recommended herein may cause damage to or jeopardize the adhesive bond.
  7. TIP: Back bend 6” to 8” at each end of extender piece by carefully rolling ends backwards. This will help straighten existing rolled memory in extender. This tip will help extender lay down flat at ends resulting in a proper adhesive bond and provide a nicer looking miter joint.
  8. Always dry run extender before final installation. Install finished rolled edge towards window and cut edge towards structure. Square cut or miter corners at top, install top piece first starting at one end pulling backing back a little at a time while lightly pressing extender down, install sides same as above. NOTE: Wait until you are satisfied with the fit before thoroughly and firmly rubbing all extenders down to mainframe face. For an optimal adhesion bond it is recommended the installer use the RWD polyurethane trim roller. This tool is highly recommended and can be purchased from RWD Innovative Specialty Trims, LLC. If immediate extender removal is necessary, you may be able to re-use existing piece, if the adhesive foam tears, you will need to re-cut a new piece and apply. TIP: Hold extender in place to check the fit before removing the backing, trim as necessary, once extender adhesive contacts with the window frame, removal may be difficult without damaging extender and adhesion bond.
  9. Clean entire window, caulk perimeter to structure, and caulk miter and square cuts. IMPORTANT NOTE: It is very important that the installer understands that although the high strength adhesive will adequately bond the extender to a window mainframe, its main purpose is to provide an instant bond so the installer can immediately apply the perimeter caulking to both the window facing, and building finish opening. Depending on the window’s mainframe style, the installer must caulk edge of extender to exterior of mainframe face where extender butts up against beveled projection or screen track. This will ensure long term adhesion and a weather tight seal.