It’s typically free to have a contractor come out, take measurements, and inspect the frame to make sure it can hold a bay window. This isn’t realistically something you can do yourself, though.
The cost of a bay window depends on the size and style you’re going for. It will likely cost $800-3,000 depending on the size and material. Bay windows come preassembled, but the siding, top and bottom panels, and roof cab are occasionally not included. If the contractor offers to cut these pieces to size for an additional fee, consider taking them up on your offer. It’ll save you a lot of work if you can get these pieces precut. The cables and hanging materials for the roof will all come with the window. The same is true for the clamps you need to hang the cables that hold your roof up.
Some window panes have a little tab that flips up instead of sliding into the middle of the window.
This may take 30-45 minutes depending on how strong the window frame is here. Be ready to make a bit of a mess and put some effort in!
Feel free to take a 10- to 20-minute break after you’re done here. Grab some water and a snack. Removing an old window frame can be quite exhausting! Don’t remove any nails holding the joists in place. Any nails that are flush in the wood joists are holding them in place and must stay in place.
Place one nail every 4–5 inches (10–13 cm) to keep the board from coming loose. If you use shims and some of them are sticking out at the sides, score the excess wood with a utility knife and break them off with a rubber mallet. You don’t have to hit hard here—just tap the wood and it should snap off.
The flashing tape functions kind of like a moisture barrier between the wood frame and the window. If any moisture gets in between the window and the surrounding joists, you window may sag or become drafty.
Double-check the edges to make sure your window is sitting perfectly in the frame on your wall.
If your window’s instruction manual tells you to use a different size screw or to temporarily hold it in the frame some other way, do that instead. You’re going to cover all of these screws anyway, so it doesn’t really matter if they aren’t beautiful. You can use a nail gun and framing nails instead if you prefer. Nails tend to be a little weaker than wood screws, but this is only a temporary measure so it may not matter if the window isn’t particularly big or heavy.
Typically, the cables go 16–24 inches (41–61 cm) above the bay window.
Do not drill the screws in all the way. Leave a little bit of room behind each clamp for the cable. The clamp looks kind of like a small rectangle with an opening on the back for a cable to slide through. You always install the clamps vertically so the short side is facing down. The height of your clamps determines the angle of the support cables. The higher up the clamps are, the more support you have for the window. However, the size of the roof cab impacts how high you can set the clamps since the roof cab goes over them.
Sometimes, the cable comes preinstalled on the bay window. Other times, there’s a small hook for you to run the cable through on the window. Whether the cables are preassembled on the bay window or not depends on the manufacturer. There’s no structural difference between pre-installed cables and cables you run through a hook.
The cables are not holding your window up. They only keep the window level and counteract the gravity trying to pull it down.
This will keep the shims from sliding around in the wall after you finish installing the window.
Insulation sheets are typically filled with fiberglass. You must wear gloves when handling it to avoid cutting yourself. Blanket, or rolled insulation refers to the soft, pliable insulation sheets you find behind drywall. You can cut the insulation if you need to using a utility knife and a spare length of wood as a straight edge.
Take your time when you’re lining up the plywood decking. It’s best if you have no exposed edges and you can’t see the cab underneath when you’re done.
There must be a 3–4 in (7. 6–10. 2 cm) lip at the top of the paper where it leads into the wall. If there isn’t, water may drip in between the window and the wall.
You can install a metal roof made of prefabricated metal sheets instead, but you must order this roof in one piece from a company that makes roofing materials. You can’t cut one to size yourself. When you’re done with everything else, spread asphalt caulking in between the shingles to seal them and keep water from seeping through. Buy shingles that match the color and shape on your roof. If you don’t have shingles, you can use any style of shingle you’d like.
Step flashing is really easy to bend by hand, but you must wear gloves to avoid cutting your hands.
For decorative brackets, you may need to cut out some siding if you have vinyl siding on your walls.
If you’ve ever done any demolition or repaired a window, you’ve seen spray foam sealant. This is that orange, puffy stuff behind chunks of drywall. It’s basically a type of insulation that keeps air and moisture from sneaking in through a gap in the wall.
These panels match the interior shape of the window at the top and bottom. Just slide them into place so all the edges line up with the glass and the edge of the window frame. Place your nails 1–2 inches (2. 5–5. 1 cm) from the edge of the frame so you can cover them with siding. Repeat this process for the interior strips that go on the side if you have any. [28] X Research source
Some bay windows come with the glass preinstalled. If this is the case, go ahead and skip this step.
