Balconies

There are several balcony types, and each is a different engineering solution. An open sun balcony, a cantilever balcony that projects from the frame without columns, a balcony suspended on a steel structure, and a column-supported balcony resting down to the ground. There is also closing an existing balcony to add area.

The choice depends on the existing structure, the ability to tie into the frame and foundations, and the permitted building zones. We examine what is possible on your plot and choose the type that gives the most without endangering the structure.

• An open sun balcony
• A cantilever balcony with no columns
• A balcony suspended on a steel structure
• A column-supported balcony and closing an existing one

The railing is the balcony’s critical safety element, and it is governed by a binding standard. The minimum height on a balcony is 105 cm, and the gaps between railing elements must prevent a 10 cm ball from passing, so a child cannot get stuck or through.

The standard also bans a sequence of horizontal rails that allows climbing, and requires meeting a horizontal load by an engineer’s calculation. A glass railing must be laminated safety glass (triplex), no less than 10 mm thick and set by the wind loads, not ordinary tempered glass.

• A minimum height of 105 cm on a balcony
• A gap that will not pass a 10 cm ball
• A structure that prevents children climbing
• Laminated safety glass, no less than 10 mm

A cantilever balcony ties into the building’s slab reinforcement and is cast as a continuous extension of the floor. A suspended steel balcony is anchored to the beams, prefabricated and lifted by crane, and is significantly lighter than concrete, a real advantage in older buildings with limited foundations.

The minimum live load for a residential balcony is about 350 kg per sqm, higher than an interior room, because a balcony concentrates people and objects at the edge. This is only a floor: a jacuzzi, heavy furniture, or planting require design for higher loads.

• A cantilever cast as a continuation of the frame’s rebar
• Steel lifted by crane, light for older buildings
• A minimum load of about 350 kg per sqm in homes
• A jacuzzi and heavy furniture require increased design

An open balcony is a flat roof in every respect, and its waterproofing is the difference between a balcony that lasts for years and damp in the ceiling of the neighbor below. The waterproofing is done to standard with polymer-modified bituminous membranes, with slopes to the drain that prevent standing water.

Before tiling, a flood test of about 48 hours is performed to find leaks, and it is a condition for occupancy. We insist on a correct drainage system, raising the waterproofing at wall connections, and testing before covering, because fixing waterproofing after tiling is expensive and painful.

• Polymer-modified bituminous membranes
• Slopes to the drain against standing water
• Raised waterproofing at wall joints and the door sill
• A 48-hour flood test before tiling

A new cantilever balcony requires a permit with a signed structural plan. Thanks to legal relief, adding a cantilever balcony up to 14 sqm and a projection of up to 2.5 meters usually goes through a short-track license, and every apartment is entitled to add a sun balcony of up to 12 sqm under rights the state added.

Note a common misconception: closing a balcony with walls turns it into primary area, consumes building rights, and requires a permit, like adding a room. The first 12 sqm of a sun balcony are exempt from the betterment levy, and there is an exemption for a home up to 140 sqm.

• A cantilever balcony up to 14 sqm usually on the short track
• A sun balcony of up to 12 sqm for every apartment
• Closing a balcony requires a permit and consumes rights
• The first 12 sqm are exempt from the betterment levy

Two engineering details separate a professional balcony from an improvisation. The first is a thermal bridge: the connection of the cantilever or steel to the outside creates thermal continuity that brings condensation, damp, and mold at the inner edge, so a thermal-break element is required. The second is corrosion protection: a steel structure requires hot-dip galvanizing, critical in a marine environment.

When everything is done right, a sun balcony is one of the most worthwhile additions, raising the apartment’s value by about 5% to 15%, alongside a real upgrade to quality of life.

• A thermal-break element against bridging and damp
• Hot-dip galvanizing to protect the steel from corrosion
• A balcony raises apartment value by about 5% to 15%
• A key demand element in urban renewal too