Spigot Glass Railing for Concrete Slabs: How It Works

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A spigot glass railing is a system where short steel spigots are cast or fixed into a concrete slab, and the glass panels are held by base shoes or clamps mounted on those spigots. It suits poured concrete balconies and terraces because the glass sits on a clean, low profile and the load is transferred directly into the slab. Planning the spigot positions before the concrete is poured is the key to a straight, safe installation.

What a spigot glass railing system is

A spigot system uses small vertical steel posts, called spigots, that project from the top surface of a concrete slab. Each spigot carries a base shoe or clamp that holds the bottom edge of a toughened glass panel. The glass itself is usually a laminated panel, and the spigots keep the railing low and visually light.

Because the posts are set into the slab rather than fixed to the edge, the system is well suited to balconies, roof terraces and open stair landings where a clean line matters.

When to choose spigots on a poured slab

Spigot railings work best when the slab is poured to its final shape and the edge is accessible. They are a good choice when the client wants minimal framing, an unobstructed view, and a railing that can follow a straight or gently curved edge.

New poured concrete balconies and terraces
Slabs with enough depth to anchor the spigots properly
Projects where the edge detail is confirmed early

Planning spigot positions before the pour

The most reliable way to fit a spigot system is to plan it during design. The positions, spacing and depth of the spigots must match the glass panel layout and the slab edge. Once concrete has cured, moving a spigot means drilling and chemical fixing, which adds time and reduces the margin of safety.

Share the edge drawing and glass layout with the railing supplier early, so the formwork and any reinforcement can be coordinated with the spigot locations.

Fixing and load transfer into the slab

The spigots must be fixed so they can resist the horizontal loads that the railing is designed for. The method depends on whether the spigots are cast in during the pour or installed afterwards in drilled holes with an approved anchoring system. Each method has its own requirements for embedment depth, concrete strength and edge distance.

Exact design loads and fixing values should be checked with the structural engineer for the specific project and building standard, not taken from general guidance.

Glass, finishes and maintenance

Laminated toughened glass is normally used with spigot systems so that a panel can remain in place if it is damaged. The steel spigots and base shoes are finished for outdoor exposure, typically with hot-dip galvanizing followed by powder coating, or with a stainless steel finish where the look is preferred.

Maintenance is simple: check the base shoe fixings and the glass seals periodically, and clean the glass edges where water and dirt collect.

Installation sequence on site

A clean installation starts with checking the spigot alignment and levels on the finished slab. The base shoes are then fitted, the glass panels are set into them and the connections are tightened and sealed. Working in this order lets the installer correct any small deviation before the glass is in place.

Confirm spigot position, height and alignment
Fit base shoes and check levels
Set and fix the glass panels
Tighten, seal and do a final inspection

Frequently asked questions

Can spigots be added to a slab that is already poured?

Yes, in many cases spigots can be fixed into an existing slab with drilled holes and an approved anchoring system. The slab condition, edge distance and concrete strength must be checked first.

Is laminated glass required for a spigot railing?

Laminated toughened glass is the normal choice because it stays in place if a panel is damaged. Final glass specification should follow the project requirements and the engineer's guidance.

Do spigot railings need to be galvanized?

For outdoor balconies and terraces, a corrosion-resistant finish such as hot-dip galvanizing with powder coating, or stainless steel, is strongly recommended. This protects the spigots and fixings from weather.

How do I know the railing meets the Israeli standard?

The Israeli railing standard SI 1142 sets the general requirements. The exact values for height, loads and fixings should be confirmed with the structural engineer for each project.

Common mistakes to avoid

The most common mistake is leaving spigot positions to the end of the job, which forces drilling into cured concrete. Another is ignoring the edge distance and concrete strength when fixing the spigots.

Our recommendation

Send the edge drawing and glass layout to the railing supplier before the formwork is set, and have the structural engineer confirm the spigot fixing method. Planning this early avoids most site problems.

Summary

Spigot glass railings give a clean, low-profile edge on poured concrete slabs, but they work best when the spigot positions are planned before the pour and the fixing is confirmed by the engineer.

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