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How-To Install a Bay Window

One of the most warm and inviting window styles is a Bay Window. It can also enlarge the size of a room and brighten a room with more natural light. Installation is easier than you think if you are a real do-it-yourselfer, and are replacing an existing window. By the way, you can add your own how-to tips at the bottom of this article. If your projects have been limited to hanging pictures and adding drawer pulls, talk to one of our experts when you select your Bay Window. You may want to hire a contractor. If you have a friend or relative who has more experience fixing and upgrading than you do, this is the time to ask for help.

Note: Manufacturers' instructions vary depending on material the window is made of, design and exterior of your house.

Ready? Put on your safety glasses and make sure you have read every word of the instructions for the tools you will be using. You also need to follow all the instructions that come with your new window. These tips assume you have pre-measured the replacement area before purchasing your new bay window and consulted your Dolan's experts. You will need some help when it comes time to lift the window into place.

Here are some tips.

  1. Remove the old window including sash, frame and frame enclosure.
  2. Measure the dimensions of your new bay window frame and square the rough opening to the new window size.
  3. Mark these dimensions on the outside of your house.
  4. Use a reciprocating saw to cut along the lines you have marked on your house.
  5. Decide what kind of supports to use -- angle wood, iron or decorative knee braces.
  6. If you are using 2 x 4 angle supports, make sure they are attached to the wall with ¼ x 4" lag screws. Make sure the support is level.
  7. Finish the bottom of your support and fill the platform area with insulation. Do not pack tightly.
  8. Lift your bay onto the support. (You will need extra hands for this depending on the size of the window.) Check the exterior side and top casing to make sure the window is level. If it isn't, check the support.
  9. After securing with nails or masonry clips, secure the sill or sub sill to the platform according to the instructions. Install the siding and caulk around the sub sill or sill and faceplate.
  10. On the inside, place insulation along the jams, header and sill. Then install shims between the rough opening and the window along the jambs.
  11. Install interior trim and paint. Many instructions include other help like masonry instructions. Remember, you can always call your Dolan's window expert if you get stuck during installation.

Material and Tools You Will Need To Install Your Bay Window

Take this list and your questions to Dolan's when you select your window. List may vary according to window manufacturer.

  • 1-1/4 x 4" lag screws
  • 16d casing nails * 8 x 1-1/2" wood screws
  • 1-1/4" roofing nails * 2 x 4's and 2 x 2's
  • Angle irons or knee braces (if not using wood supports)
  • Insulation
  • Shim stock
  • Plywood or similar sheathing
  • Enclosure material
  • Caulking gun
  • High quality exterior caulking
  • Interior casing Paint
  • Hammer
  • Electric circular saw
  • Masonry saw or chisel and hammer if home is masonry
  • Square
  • Tape measure
  • Level
  • Flat screwdriver
  • Nail set

Visit any of Dolan's five Bay Area locations for more information.