Balcony Cost Calculator

Frequently asked questions

How much does it cost to build a balcony?

A 12 by 6 ft composite balcony on posts, 10 ft above grade, with an aluminium railing typically lands between $6,500 and $11,500 including drawings and permit. Cantilevered framing adds roughly $1,300 to $2,400 on that size, and a waterproof membrane for living space underneath another $1,000 to $2,000. Per square foot, expect $90 to $160 — well above a ground-level deck.

Why is a balcony more expensive than a deck?

Three reasons. The work happens at height, which slows everything and adds staging. The support is harder — cantilevers and wall brackets have to transfer load back into the building's floor structure, which usually means an engineer. And the guard rail carries a real code load with a real fall behind it, so the posts, blocking and connections are all heavier than the same railing on a low deck.

Do balconies need waterproofing?

Only if there is conditioned space, storage or an entry beneath. When there is, the balcony stops being a deck and becomes a roof: it needs a continuous membrane, a slope to drain, and flashing integrated with the wall — not open board joints. Retrofitting that later costs far more than building it in, because the deck surface has to come off.

Can I replace a rotten balcony myself?

The decking and railing, sometimes. The structure, rarely — because the parts that fail first are the ledger and the framing ends buried in the wall, and you usually cannot tell how far the damage goes until the finish comes off. Balcony collapses almost always trace back to concealed rot at the wall. This is the one deck job where an inspection before you start is worth the fee.