How To Install A Vinyl Window With Nail Flanges So It Is Waterproof And Sound

Vinyl windows are an economical, lightweight and durable choice if you are updating or renovating your home. There are different ways to mount vinyl windows, but nail flange installation is simple and reliable. However, it is critical that you install your vinyl windows correctly, or water may be able to enter your home or cause wood rot in unprotected areas. Below is a list of materials and tools you will need as well as a step-by-step procedure for installing vinyl windows with nail flanges:

Items you will need to perform the installation

  • Vinyl window with nail flange in appropriate size
  • Rough opening cut in specified size for window
  • Sill flashing corner pieces (2)
  • Peel-and-stick EPDM membrane flashing
  • Membrane spray primer
  • ¼-inch plywood scrap
  • Silicone caulk
  • Caulk gun
  • Claw hammer
  • Utility knife
  • Wallpaper roller
  • Measuring tape
  • Saw
  • Whisk broom
  • Wet/dry vacuum
  • Hair dryer or heat gun
  • 2-inch 10d nails

Step-by-step procedure for installation

1. Thoroughly clean the rough opening and surrounding area - The peel-and-stick EPDM membrane used for hanging your windows demands you clean the wood surfaces within the rough opening itself and the border of the opening, too. Vigorously sweep the wood with a whisk broom to remove shavings, sawdust and other debris that will interfere with the adhesion of the membrane and wood. Following that, vacuum the surfaces using a wet/dry vacuum so that the wood is completely clean and ready for the application of the membrane.

2. Attach the sill corner flashing pieces - After ensuring the rough opening is clear of debris, apply a line of silicone caulk to the undersides of your two sill flashing corner pieces. Next, stick the corner pieces into both bottom corners of the rough opening and hold them in place for a few seconds so they are well-seated. Once you attach them, drive a couple of 10d nails through the soft plastic of the flashing pieces to secure them to the wood. If any part of the corner pieces extends over the sill into your home, use a utility knife to cut away material so the edges of the corner pieces are ⅛-inch from the edge of the sill.

3. Prime the rough opening - Once the sill corner flashing pieces are installed, spray a thin layer of membrane primer on the wood surfaces of the rough opening and the surrounding areas, including on top of the corner pieces. If the primer coalesces and drips from the wood, you have either sprayed too much or the wood is too cold. Heat the wood with a hair dryer or heat gun to help warm it up should the primer fail to adhere. This will also help the EPDM membrane to better adhere.

4. Attach the EPDM membrane to the sill - After priming the wood, carefully peel away the protective back liner on a strip of EPDM membrane that is approximately 6 inches longer than the width of the rough opening. Center the strip of membrane on the bottom of the rough opening so the top of the strip it is flush with the sill base. Push it into position, and use a wallpaper roller to flatten it and remove air bubbles.

Next, cut a strip of EPDM membrane to the same width as the previous piece, and remove the back liner; place the piece so it slightly overlaps the first strip and partially covers the bottom of the rough opening. After that step, cut the membrane in a perpendicular direction down along the inside edge of the rough opening and fold the membrane flap over the top of the sill. Again, flatten the membrane and remove bubbles with the wallpaper roller.

5. Apply caulk to the opening - Once the membrane is in place around and on the sill, cut two small shims from a scrap piece of ¼-inch plywood. Each shim should be approximately 1 inch by 2 inches in size, but don't worry if they are off by a half-inch either way.

Next, attach the shims to the sill plate using caulk; space them so they divide the sill into thirds. Following that, apply a line of caulk around the entire perimeter of the rough opening. Pick up the window and carefully slide it into the rough opening. Push it firmly into position so the nail flanges rest flat against the wall and hold it for a few seconds to allow the caulk to spread and seal the window.

6. Install the window and finish applying membrane - After the caulk has set, continue to hold the window in position and nail 10d nails into the flange holes. Be sure not to hammer too hard, or you may warp or break the flange. Next, measure along the vertical edge of the window and cut two strips of membrane equal to this length plus 6 inches. Peel off the backing on one strip and apply it along the edge of the window so it covers the nail flange; repeat the process of peeling and sticking for the other side of the window. Don't forget to use the roller to increase the strength of the bond between the window and membrane.

Finally, finish up the window by measuring and cutting a strip of membrane to apply along the top of the frame. Apply the membrane and roll it out for a more secure bond.


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