How to Add a Balcony to a House

A balcony extends the use of an upper-story room by providing an additional space to enjoy the sun, entertain guests or simply relax.
Whatever the size, a balcony adds a space to relax.Whatever the size, a balcony adds a space to relax.
Whether it is a large space to barbecue on or a small window area with a table, a balcony adds a touch of style and class to the home that everyone can enjoy. You can learn how to build a balcony onto your home and increase its value, without incurring expensive contractor's fees.

Step 1

Sketch the size and shape of your proposed balcony and make note of its required length and width. Measure and cut 2-by-10 inch, pressure-treated lumber to the width of the balcony with a circular saw to form the ledger. Drill holes through the wall and the timber at 1-foot intervals. Bolt the ledger to the wall through the holes with 6-inch lag bolts.

Step 2

Cut two pieces of 2-by-10 inch, pressure-treated lumber to 2 feet in length. Place the first timber vertically on the wall beneath the left edge of the ledger. Drill holes through the timber and into the wall. Secure the timber to the wall with 6-inch lag bolts. Repeat with the other timber on the right side of the ledger.

Step 3

Screw the joist hangers to the timber ledger so there is one joist hanger on either end of the ledger and an additional joist hanger every 1-1/2 feet along the length of the balcony. Cut two lengths of 2-by-10 inch, pressure-treated lumber to the length of the balcony. Cut additional lengths of timber to the balcony length to fasten one timber to each floor joist.

Step 4

Attach the timbers to the floor joists with a hammer drill and long screws. Cut a piece of 2-by-10 inch, pressure-treated timber to the width of the balcony. Screw this timber to the ends of the floor joists with long screws. Reinforce the joints with 6-inch wide L-brackets.

Step 5

Measure 2 inches from the bottom of one vertical timber attached to the wall to the outer edge of the balcony. Cut two 2-by-10 inch, pressure-treated timbers to this length to form the knee braces for the balcony. Bolt one knee brace to either side of the balcony with heavy-duty gusset plates on either side of the joints.

Step 6

Cut sheets of 1-inch-thick plywood to the length of the balcony and 3 feet in width. Apply wood glue to the top of the floor joists. Screw the plywood to the top of the floor joists to form the balcony subfloor. Cut four pieces of 2-by-2 inch, pressure-treated timber to 2-1/2 feet in length. Screw one 2-by-2 inch piece vertically into each corner of the balcony with mounting brackets.

Step 7

Measure the distance between the side and front corner support posts. Cut two lengths of 2-by-2 inch, pressure-treated timber to the distance between the back and front support posts. Cut one piece of 2-by-2 inch, pressure-treated timber to the distance between the two front support posts. Screw the timbers between the support posts with L-brackets to form the handrail. Repeat this process to mount a second handrail 1-1/2 feet from the balcony floor.

Step 8

Varnish, stain or paint the balcony and the handrails as desired. When the varnish or other treatment is dry, lay the balcony floor. This can be made from any material you wish, such as ceramic tiles, a concrete slab or even wooden decking. Allow the flooring material to set or dry thoroughly before using the balcony.

Things You Will Need

  • Tape measure
  • Circular saw
  • 2-by-10 inch, pressure-treated timbers
  • Hammer drill
  • 6-inch lag bolts
  • Joist hangers
  • Long screws
  • L-brackets
  • Heavy-duty gusset plates
  • 1-inch-thick plywood sheets
  • 2-by-2 inch, pressure-treated timbers
  • Mounting brackets


  • For a more sleek, modern look, consider replacing the wooden handrail with a metal one. Metal handrails are easier to keep clean, do not need to be regularly varnished or painted and can be substantially thinner than wooden rails so they obscure less of your view.


  • Many states and local jurisdictions require permits before you can erect a balcony on your property and levy substantial fines where permission is not granted before the structure is built. Always check with your local planning department to see whether you need a permit before starting work on a balcony.

About the Author

Based in the United Kingdom, April Kohl has been writing since 1992, specializing in science and legal topics. Her work has appeared on the Second Life News Network website and in British Mensa's "LSQ" magazine. Kohl holds a Bachelor of Science in physics from Durham University and a diploma in English law from the Open University.