Add skirting for an attractive finishing touch to your two-level deck.
If a deck is raised high enough that you can see under it, you may want to cover the framing and footings with skirting. Unless you live in a dry climate, make sure the skirt provides enough ventilation that the area underneath can dry out between rainfalls. If you install skirting made of solid 1xs instead of lattice, leave at least 1/2-inch spaces between the boards. The vinyl lattice shown here is ideal -- it won't rot and it requires no painting.
Making it strong enough
If the skirt will be less than 2 feet high and in a low-traffic area, attach it to the joist leaving its bottom edge unsupported. For a skirt that can withstand bumps from a lawn mower or errant soccer ball, frame along the bottom: Tie the horizontal piece at the bottom to the posts under the deck, keeping it at least 3/4 inch above grade. Use only pressure-treated lumber.
If you want to use the space under a deck for storage, frame one of the skirt sections with 2x4 or 1x4. For occasional access attach the section with screws that can be removed. If you need access often, install hinges and a latch.
About a day to frame and install about 40 feet of lattice skirting
Tape measure, post level, drill, hammer, circular saw, handsaw, square, string
Improvising a framing plan, cutting boards, fastening with screws or nails
Choose a skirt material that suits your needs, estimate materials for framing
2x4 for framing, lattice panels or other skirt material, 1x2 or 1x4 for trim, 7/8-inch roofing nails, 2- or 3-inch deck screws or nails
Make a vertical support by cutting one 2x4 so it reaches from behind the joist down to 3/4 inch above grade. Cut a facing 2x4 to extend from the bottom of the joist to the top of the horizontal support. Plumb the support; attach the pieces with 3-inch screws. Install the horizontal pieces.
At an outside corner, attach two outriggers to hold the horizontal 2x4s firmly. Cut the end of a horizontal piece with a handsaw. The 1x4 trim will overlap at the corner. If the horizontal 2x4 follows the grade, decide whether the lattice and trim also should follow the grade. It may be best for appearance to level the lattice and trim even if some of the horizontal 2x4 will show. (Hide it with plantings.)
Lay the lattice on scrap pieces of lumber so you have a stable edge for cutting. Mark the lattice for cutting using a chalk line or a framing square and pencil (a drywall T square is even better if you have one). Cut the lines with a circular saw, setting the blade so it extends 1/4 inch beyond the lattice.
Notch the lattice to fit tightly along the sides of the railing posts. All other lattice edges will be covered by 1x4 trim, so cut the lattice about 1/4 inch short for easy installation. Buy 7/8-inch galvanized roofing nails to fasten the lattice in place. Use just enough nails to keep the lattice from sagging -- 1x4 trim will actually support it.
Install the trim of your choice. In this example, 1x4 is used -- would work as well. Start by installing the horizontal trim, fastening it into the bottom 2x4 frame and the outside joist with two 2-inch fasteners every 18 inches. Beneath the deck posts, add trim to cover the vertical skirt frame. Finally add trim under the decking. Just a portion of the joist will show through the lattice.