How to Build a Balcony to Expand Your Outdoor Space

Use an auger or post hole digger to create four post holes. Again, check local ordinances to determine how deep the holes need to be for a balcony or second-story deck. Each post hole should be three times the diameter of the piece of lumber.

Place your 4-by-4 or 6-by-6 posts into the hole, then fill with cement to secure them. You'll likely need an extra set of hands for holding the beams still as one person pours cement and sets it. Read your quick-drying cement instructions and follow them carefully.

If you're building an especially heavy or large deck, insert rebar into the top of each post hole.

The first step for building the balcony frame is to secure a ledger board to your rim joist. You'll need to remove siding from the home to get direct access. Use lag screws to drill the board into your foundation—approximately every 12 inches.

The ledger should be as close to the home as possible. Assuming an entryway is above it, the board should be as fit and snug as possible underneath to prevent water seepage from rotting the wood over time. Install flashing or caulk when you're finished to prevent leaks.

To build the frame, attach the 2-by-6s to the ledger board. The outside portion of your balcony should be double-framed for support. Use two boards cut to the same length on all three sides not touching the rim joist. Screw them in with two lag screws fitted to a corner bracket.

If possible, position your double frame directly underneath a double stud in the wall. Use a stud finder to locate stud points and mark them with a pencil or pen.

Lastly, attach your frames to the posts using lag screws and a corner bracket.

Install the balcony joists or wood beams that'll form the base of the floor. Insert a 6-inch board every 12 inches, starting at the rim joist, then securing it to the opposite side of the frame.

You can buy deck boards at home improvement stores for around $20 per piece. It's up to you whether you'd like to cut these into individual 12-inch pieces and layer or install them as one long beam across your hoists.

Deck boards are usually 5 1/2 inches wide and 1 inch thick. You'll establish the board length needed after determining the size of the balcony. Use screws to fasten boards to your joists. Work slowly and use nails to reinforce if needed.

For railings, you can either use lumber or buy a premade balcony railing kit from a home improvement store. The latter will cost between $60 and $100 for 6 feet of railing.

Read the manufacturer’s directions on your kit. In either case, you'll likely need to drill holes every 3 to 6 inches—depending on railing gaps—into your doubled-up balcony frames. Drill starter holes, then fasten using screws or as described on the packaging.