Balconies in floor plans

In this guide

1. 1

   Balcony types — five categories

   Rectangular balcony. A balcony projecting straight outward from one exterior wall. - The most common configuration. - Sizes 60–144 inches wide × 36–72 inches deep. - Supported by cantilever framing or by columns from below. - Best for: bedroom balconies, master suite balconies, second-story sitting balconies. L-shaped balcony. A balcony wrapping the corner of a building, spanning two adjoining exterior walls. - Two segments meeting at 90°. - Sizes 60–144 inches per side. - Common in corner units of multi-unit buildings and view properties. - Best for: balconies serving multiple rooms; view-side properties. - See l shaped balconies for the deep-dive. Juliet balcony. A decorative balcony that doesn't actually provide standing room — just a railing or guard outside a door or window. - Very shallow projection (12–18 inches) or zero projection. - Functions as a 'safety rail' for a floor-to-ceiling opening rather than usable outdoor floor. - Common in European apartments, brownstone conversions, and contemporary urban infill. - Best for: providing safety for floor-to-ceiling doors when actual balcony depth isn't practical. Cantilevered balcony. A balcony supported entirely by cantilever framing — no visible columns or supports below. - Sleek, modern aesthetic. - Structurally limited to ~6 feet maximum projection without supplemental support. - Requires engineered framing. - Best for: contemporary architecture where visual cleanliness is the priority. Supported balcony. A balcony with visible columns or posts from below carrying the load. - Allows deeper projection (12+ feet) than pure cantilever. - Often used in larger luxury homes or where columns are part of the design. - Best for: deep balconies, traditional architecture where columns are appropriate, balconies on lower floors that double as porch roofs above. Recessed balcony (inset balcony). A balcony set into the building envelope rather than projecting outward — the building's floor plan has a notched-in area that becomes the balcony. - Structurally simpler (no projection load). - Provides more shelter from weather (the building wraps the balcony on three sides). - Common in apartments and condos. - Best for: weather-exposed climates, multi-unit buildings, contemporary urban architecture.

2. 2

   Standard sizes by use

   Juliet balcony (decorative). - Projection: 0–18 inches. - Width: matches the door or window (60–96 inches typical). - Use: provides a guard rail for a tall opening without actual standing room. Bedroom balcony (small sitting). - Projection: 36–48 inches. - Width: 60–84 inches. - Use: standing area; one or two chairs. Master suite balcony. - Projection: 48–72 inches. - Width: 96–144 inches. - Use: sitting area with multiple chairs and a small table. Living area balcony. - Projection: 60–96 inches. - Width: 120–240 inches. - Use: substantial sitting area; small table; sometimes lounge chair. Outdoor room balcony. - Projection: 72–144+ inches. - Width: 144–360+ inches. - Use: multiple seating zones; dining table; outdoor kitchen. Railing height. - Single-family residential: 36 inches minimum (most code). - Multi-family residential: 42 inches minimum. - Above 30 feet from grade: typically 42 inches minimum. Baluster spacing. - Maximum 4 inches between balusters (so a 4-inch sphere cannot pass through). This is consistent across most US code. Total area calculations: - 36 × 60 inch Juliet: 15 sq ft (decorative only). - 60 × 96 inch master balcony: 40 sq ft. - 84 × 144 inch living balcony: 84 sq ft.

3. 3

   Structural construction

   Cantilevered balcony construction. The balcony is supported by floor joists that extend out from the building interior to the balcony exterior. The cantilever creates a moment (rotational force) at the connection to the building, which the interior framing must resist. - Cantilever ratio: balcony joist length outside : interior length. Typical residential: 1:2 (interior length twice the cantilever length). A 3-foot cantilever requires 6 feet of interior anchor framing. - Joist size: 2×10 or 2×12 for typical residential cantilever. LVL (laminated veneer lumber) or PSL (parallel strand lumber) for longer cantilevers. - Reinforced connection: hold-down hardware, doubled joists at the connection to the building. - Maximum projection: ~6 feet for pure cantilever in standard 2×10 framing; longer with engineered lumber. Supported balcony construction. Columns, posts, or knee braces from below carry the balcony load. - Columns extending to grade: most common for porches that double as balconies above. - Knee braces: triangular brackets from the building wall to the underside of the balcony floor. Allow projection of 4–6 feet without ground-level columns. - Columns supporting from lower roof: balcony supported by columns extending up from a porch or lower-story roof. Recessed balcony construction. The building's floor plan steps inward; the recessed area becomes the balcony. - No cantilever; standard floor framing. - The wall above the balcony is supported by columns or beams at the balcony perimeter. - Roof above the balcony is the main building roof. Foundation considerations. Supported balconies with ground-level columns need column footings — separate concrete piers supporting each column. Cantilevered and recessed balconies don't require column footings. Lateral and seismic. Balconies are structurally weaker than enclosed building elements. Seismic and high-wind code may require additional bracing.

4. 4

   Railings

   Railing height. US residential code: 36 inches minimum. Multi-family: 42 inches minimum. Always 42+ inches for railings above 30 feet from grade. Baluster spacing. Maximum 4 inches between balusters (the small vertical pickets between top and bottom rails) so a 4-inch sphere cannot pass through. This applies to all balusters regardless of railing style. Railing styles (matches railing styles for interior walls — see [[railing-styles-spindle-glass-cable-fence]]): - Spindle (traditional). Vertical wood or metal balusters. Federal, Colonial, Victorian. - Glass panel. Tempered glass panels in steel or aluminum frames. Contemporary, modern; preserves view. - Cable. Horizontal stainless cables tensioned between posts. Industrial, mountain modern, modernist. - Wood fence. Solid or semi-solid wood boards (vertical or horizontal). Rustic, farmhouse, Mediterranean. - Brick wall. Half-wall of brick up to railing height. Masonry architecture, traditional. Railing materials: - Wood: traditional; requires periodic refinishing. - Wrought iron: heritage; cast or forged. - Aluminum: contemporary; powder-coated. - Steel: industrial; powder-coated or galvanized. - Stainless steel cable: modern; saltwater resistance. - Tempered glass: modern; view-preserving. Top rail. A horizontal rail at the top of the balusters — provides hand support and structural connection. Must support a code-specified weight (typically 200 lbs concentrated force at any point). Handrail requirement. On stairs accessing the balcony, handrails are required at 34–38 inches high. On the balcony itself, the top rail serves as the handrail.

5. 5

   Drainage and weather

   Balconies are exterior surfaces exposed to rain and snow. Proper drainage is critical to prevent water infiltration into the building. Slope. Balcony floor must slope away from the building — typically 1/4 inch per foot away from the building. This drains rainwater away from the building wall and into the outdoor environment. Waterproof membrane. Modern balcony construction includes a waterproof membrane below the finished floor (deck boards, tile, concrete topping). The membrane prevents water that gets past the finished surface from reaching the structural framing. Drains. Larger balconies (and any balcony with parapet walls or other features that prevent water from running off the edge) require drains. Typically: - Scuppers (openings in the parapet at low points) draining to downspouts. - Floor drains with piping to the building drainage system. Flashing. Where the balcony meets the building wall, flashing prevents water from penetrating the joint. Step flashing between siding and balcony; tape and membrane integrated with the waterproof membrane. Materials for balcony floor: - Concrete: durable, low-maintenance; common in apartments and condos. - Wood deck boards: traditional residential look; requires periodic staining/sealing. - Composite decking: low-maintenance; modern residential. - Tile or stone: premium; requires proper installation over waterproof membrane. - Synthetic membrane (TPO, EPDM): commercial/industrial; durable but not aesthetically refined. Cover or roof. Some balconies have a roof above (porch-style covered balcony). Others are uncovered (true open balcony). Covered balconies have additional shelter; uncovered are weather-exposed but provide more sky view.

6. 6

   Code requirements

   Railing height. 36 inches minimum residential single-family; 42 inches minimum multi-family. Verify local code. Baluster spacing. Maximum 4 inches. Most US code; some jurisdictions stricter. Load capacity. Balcony must support 60 psf (pounds per square foot) live load typical residential (occupants and furniture); some jurisdictions require higher for assembly use. Concentrated load. Top rail must support 200 lbs concentrated force at any point. Drainage. Slope away from building; proper waterproofing. Exit/egress. Balconies are not generally required as egress (the bedroom or living area inside has its own egress windows). But balconies often serve as 'private outdoor space' for code purposes in multi-family residential. Setbacks. The balcony's outer edge may need to be within property setbacks. Some setbacks measured from the building face; some from the balcony face. Lateral and seismic. Engineering review for any balcony projecting more than 4 feet or in seismic/wind zones. Local variations. Specific code requirements vary by jurisdiction.

7. 7

   Cost ranges — US 2024 installed

   Juliet balcony (railing only): - $1,500–4,500 installed. - Materials: railing, attachment hardware. - Labor: minimal. Small bedroom balcony (60 × 48 inches projecting): - $4,000–10,000. - Includes: structural framing, flooring, railing, finish. Master suite balcony (84 × 60 inches): - $6,000–15,000. - Includes: framing, flooring, railing, modest finish. Living area balcony (144 × 96 inches): - $12,000–35,000. - Includes: structural framing, deck flooring, premium railing, weather sealing. Cantilever construction premium: Often 30–60% premium over a supported balcony of the same size because of structural engineering. Premium railing upgrade: - Glass panel: $200–400 per linear foot. - Stainless cable: $100–250 per linear foot. - Wrought iron custom: $300–800 per linear foot. Roof above balcony (covered): - Adds 20–50% to base cost. Retrofit cost premium: Adding a balcony to an existing building is typically 50–150% more expensive than including it in new construction, because of the structural and finish work required to integrate with existing walls and floors.

8. 8

   In Room Sketch 3D

   Room Sketch 3D's Build Panel → Balcony section provides two tiles: 1. Balcony — rectangular balcony projecting from one wall. Set width, projection, and railing style in the Inspector. 2. L-shaped Balcony — wrapping a corner. See l shaped balconies. In 3D View, balconies render with the floor projection, railing per chosen style, and the building's exterior wall behind. Railings render visibly; the floor renders as a flat surface. Smart Flow Check treats the balcony as exterior space — accessible from the room behind it (via the door or window that opens onto the balcony) but separate from the room's interior floor area.

Common confusions

Related guides