Introduction: How to Install or Upgrade Lattice Below a Bay Window

About: If there's one thing I've learned about being an adult, it is this: there's always another project. Over the years, I've tackled a ton of projects and built some cool stuff, and now I'd like to help people wh…

The old owners of my house covered up the empty space below the kitchen bump-out with some cheap lattice. Not only did it look horrible, but it wasn't very well attached and came down anytime the wind was higher than 5 mph. To check another thing off the honey-do list, I spent a couple hours one Saturday replacing the old lattice with some new, modern-traditional lattice with a more robust supporting frame.

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  • (1) 2x2x4ft, pressure treated, can commonly be bought as deck railing balusters
  • (2) 2x4x8ft, pressure treated
  • Vinyl lattice sheets, sufficient to cover the area
  • 1 pack white painted wood screws, exterior grade
  • (3) galvanized right-angle brackets, Simpson Strong-Tie A21 or similar
  • (2) 2ft pieces of rebar
  • (4) 1/2" conduit clamps
  • 2-1/2" exterior rated pocket hole screws
  • 2" to 3" Tapcon screws suitable for brick work


  • Hand saw, circular saw, or miter saw
  • Pocket hole jig
  • 2-foot level
  • Hammer drill
  • Masonry drill bit for Tapcon screws
  • Impact driver and/or power drill
  • Wood drill bits
  • Hack saw or angle grinder with cutoff wheel
  • Table saw (optional, but cutting the angled bevels on the support posts will be difficult without one)

Step 1: Cut and Pre-Drill the Posts

Start by measuring the required length of the support posts that will be put at each corner, and also the length of the posts that will be anchored to the exterior wall. Allow for an inch or so gap at the bottom to help keep the posts dry. Use a saw cut the 2x4 to length for each of the posts. The posts that are attached to the wall can be made from a 2x4 ripped in half width-wise, forming two pieces that have cross-sections about 1-1/2" x 1-3/4".

The tops of the posts will eventually be screwed into the bottom of the bay window framing. One way to do this is to use a pocket hole jig to create the screw holes, which is a quick and easy way to get the job done if you have it. Otherwise, right-angle brackets could also be used. Use the pocket hole jig to make two pocket holes in the top back of the posts.

So that the lattice matches the angles of the bay window, use a protractor to measure the angle of the corner. Mine happened to be 124 degrees. Knowing this, the angle of the beveled cuts can be determined. Subtract 124 degrees from 180 degrees and divide that in half, which results in a bevel angle of 28 degrees for me.

Set your table saw to this angle and adjust the fence so that the bevel cuts intersect at the center of the post. Carefully make the bevel cuts on the post - this is a somewhat dangerous cut. These cuts should be on the front face of the posts, which is opposite of where the pocket holes are drilled.

Step 2: Install Posts Against Brick Wall

Take one of the 2x4 pieces you ripped in half width-wise and put it against the brick wall. Use a level to make sure that the post is plumb - after all, we don't want crooked lattice! I found it easy to use my foot to hold the post in place, leaving my hands free to work for the next steps.

With the masonry bit in the hammer drill, drill into the brick at either the top or bottom of the post. Drill only one hole for the time being. After drilling one hole, use a drill or impact driver to drive in the Tapcon screw, fastening the post to the brickwork. Check for plumb again with the level, and make adjustments if needed. Drill a second hole at the opposite end of the post, and fasten it with another Tapcon. You shouldn't need more than these two screws, but feel free to add more if you desire.

Repeat these steps at the other side of the bay window.

Step 3: Install Other Posts and Paint

Using a hack saw or angle grinder, cut the 2-ft pieces of rebar in half, resulting in four 1-foot long pieces. These are used to anchor the bottom of the posts and keep them from moving side to side.

Take one of your posts and place two of the pocket hole screws in the pre-drilled holes at the top. I usually screw these in just enough that the tip of the screw barely protrudes out of the mating end. This gives the piece a bit of grab onto the thing you screw it to so that it doesn't move around while you're fastening it. Using a drill or impact driver screw the post into the bottom of the bay window, being sure to keep the bevels aligned with the exterior siding. Use the level to check that the beveled faces are plumb, and hold the post in place with something heavy at the bottom.

Grab one of the cut pieces of rebar and use a sledge hammer to drive it into the ground directly behind the post and roughly centered on the post. Leave about 2" sticking above the ground. Use a 1/2" conduit clamp and a screw to fasten the back of the post to the piece of rebar, which will keep the bottom from moving around. The post is now anchored in position and shouldn't move.

Repeat the above steps to install the remaining posts. Once you're satisfied with the post installation, paint them with an exterior grade paint to match whatever color scheme you've chosen.

Step 4: Fabricate and Install Middle Supports

In this step we'll fabricate some supports for the middle of the lattice span, which will just help keep the lattice from bowing inwards too much under high wind. These go between the tops of the posts, under the bay window, behind the lattice.

These are easily made with a short section of 2x2 with an attached right-angle bracket. Simply cut 3"-4" of the 2x2 with a saw, then pre-drill and drive in a couple of screws to fasten the bracket. The 2x2 is very susceptible to splitting if you don't pre-drill the holes.

Locate the approximate mid-point between the tops of the posts and attach the supports underneath the bay window with a couple of screws. These supports should be aligned with the edge of the bay window.

Step 5: Measure and Cut Lattice

For this step, start by measuring from the wall to the intersection of the bevels on the first post. Set your table saw fence to this distance and cut the lattice to width. This can also be done with a circular saw, or even a hand saw if you're patient enough.

Repeat for each of the openings. Don't just cut from the last cut location - pay attention and plan the cut locations in the pieces of lattice to produce in a nice, symmetric looking final result.

Step 6: Install the Lattice and Finished!

After cutting all of your lattice pieces, all that's left to do is fasten them to the posts and supports.

Starting at one side, use the white-painted screws to fasten the lattice panel. I recommend screws at the top, bottom, and middle of the posts and also at the top-middle support. This should very securely hold the lattice panel in place.

Repeat all the way around the window, and you're finished!

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