Steel balconies, walkways and balcony railings

Open balconies: cantilevered, posted or hung off the wall

There are three honest ways to hold a balcony up. Cantilevered balconies run steel beams back into the floor structure, which gives a clean underside but means opening the floor up and fitting a thermal break at the wall, so it suits new builds and big extensions. Posted balconies stand on two or four galvanised columns to pad foundations, put almost no load on the wall and are the usual answer on an existing house. Hung balconies bolt a frame to the wall on brackets with a raking strut or tie beneath; they are light and quick to fit, but the wall has to be up to it. At the survey we look at the wall build-up, the floor zone and what is underneath, then recommend one and draw it with the calculations building control needs.

Loads, guarding heights and building control

A balcony on a house is designed for an imposed load of 1.5 kN per square metre, the same as the floor it leads off, plus the weight of the steel and decking; communal balconies on flats are designed for more. The guarding has to be 1100 mm above the finished deck under Approved Document K, with no gap a 100 mm sphere can pass through, and BS 6180 sets the handrail load for an external balcony at 0.74 kN per metre, more where crowds can gather. The steel is sized to BS EN 1993 and the drawings and calculations go to building control with your application, or to your builder's engineer if one is appointed. Fixings into the wall are specified by pull-out load, not guesswork, and resin anchors into old brick are proof-tested on site.

Decking, drainage and the underside

What you walk on matters as much as the frame. Galvanised open-grid steel decking drains itself, never puddles and is what we fit on walkways and fire escape balconies. Chequer plate costs less but holds water unless it is laid to a fall. If you want boards on a house, the frame is built to carry timber or composite decking and your builder lays it; boards are not allowed on blocks of flats over 18 metres, where the deck has to be non-combustible. Solid decks are set to a fall of around 1 in 80 to a drip edge or a gutter, and every hollow section is drilled so it cannot fill with water and freeze. Where the balcony sits over a door or a path we can add a solid soffit so nothing drops through.

Balcony railings and balustrades for blocks of flats

A lot of balcony railing work is replacement: the 1960s and 70s blocks around Croydon, Bromley and Orpington where the original mild steel has rusted at the base and the concrete around the fixings has spalled. The survey covers every balcony, not a sample, because the fixings and the edge condition vary from floor to floor. New railings are hot-dip galvanised and powder coated, side-fixed to the upstand on stainless brackets where the top surface is too broken to take a base plate, with vertical bars set so no gap exceeds 100 mm, or glass infill. On blocks over 18 metres, Approved Document B and the ban on combustible materials rule out timber handrails and plastic trims; everything has to be steel, glass or aluminium. We give the managing agent a fixing schedule and drawings for building control.

Access walkways and fire escape balconies

An external walkway on a block of flats, a school or an industrial unit is a balcony that runs the length of the building, and the same rules apply with a few extras. Guarding is 1100 mm, the deck is open-grid galvanised steel so it stays dry and non-slip in winter, and where the walkway is part of the escape route the width, headroom and the doors opening onto it have to satisfy Approved Document B. We fabricate walkways in bolted sections that go up from a scaffold or a cherry picker without hot works on site, on galvanised columns to pad foundations or brackets to the structure. Handrails can be welded tube, or tube and clamp fittings where you might extend the run later. Everything is hot-dip galvanised, powder coated on top if you want a colour.

Glass and steel balcony systems

If you want the view, the balustrade on the balcony can be glass rather than bars. On new glass and steel balconies that is straightforward: the glass sits in a channel welded into the frame, or on stainless posts, and the frame is designed for it. The glass is 10 mm or 12 mm toughened with a stainless handrail, or toughened laminated where you want no handrail. Frosted panels or a frosted band give privacy from the neighbours without losing the light. On a house the usual mix is a frame powder coated in anthracite or black with a satin stainless handrail, which keeps the cost down against an all-stainless balcony. The glass is ordered to measured sizes once the frame is up, so it is the last thing on and the last thing to wait for.

What a balcony costs and how long it takes

Price is driven by the size of the platform, how it is supported, the decking and the balustrade. A posted metal balcony with bar railings and grid decking is the cheapest; a cantilevered one with glass is at the other end. Access is the hidden cost: a balcony at the back of a terrace with no side access needs a crane or a scaffold, and we say which at the survey. Custom balconies are made to the opening. Send photos and rough sizes and you will have a written estimate within the working day; after the free survey the quotation is fixed unless the design changes. Drawings and calculations come next, then fabrication, then galvanising and coating at outside plants. Allow several weeks from a signed-off drawing to fitting, longer if planning or building control is still open.

Straight answers on balconies