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What a balcony costs to build or replace, including the parts a deck never needs.
With these inputs:
| Result | Value |
|---|---|
| Estimated balcony cost | $5,369 – $9,323 |
| Per square foot | $75 – $129 |
| Balcony area | 72 sq ft |
| Railing | 24 linear ft |
| Structure and decking | $3,629 – $5,443 |
| Height allowance | ×1.05 at 10 ft — access, staging and post size |
| Railing | $1,320 – $2,280 |
| Permit, drawings and engineering | $420 – $1,600 |
A balcony costs meaningfully more per square foot than a ground-level deck of the same material because almost every line item is harder: the framing is elevated, the railing has to resist a 200 pound load at the top rail with nothing beneath it, and any living space underneath turns the deck surface into a roof that must shed water. Cantilevered and bracket-supported balconies nearly always need a stamped drawing. Ranges are national estimates and exclude repairs discovered once the old balcony comes off, which on a replacement are common.
A balcony is a deck with none of the easy options. It is elevated, it usually cantilevers or hangs off the wall, it needs waterproofing if there is anything underneath, and access means working at height. This prices all of that separately so the number reflects a balcony rather than a ground-level deck of the same size.
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.
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.
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.
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.
Need the whole roof at once? The free roofing calculator works out roof area, squares, shingle bundles, underlayment, drip edge, ridge cap and installed cost from one set of measurements.