Before BalcoDeck®: How Were Balustrades Installed on Finished & Waterproofed Terraces?

And What Alternative Solutions Have Existed Until Now?

For years, architects and installers have struggled with a persistent problem: how to install balustrades on terraces that are already finished and waterproofed—without compromising the membrane, drainage, or structural performance.

BalcoDeck® was designed specifically to solve these challenges. But to understand why it’s such a departure from the past, it’s useful to look at how balustrades have traditionally been installed, the categories they fall into, and the waterproofing strategies (and compromises) that have been used until now.

This article summarises the three historic approaches and highlights the limitations they introduce when used on modern roof terraces.

The Three Traditional Balustrade Categories

Based on common industry practice, balustrades installed onto finished waterproof surfaces fall into three primary categories:

Structural glass balustrades using a continuous structural channel
Post-based balustrades (with or without top/bottom rails or glass clamps)
Hybrid balustrades where structural strength is achieved through handrail continuity, allowing no vertical posts

Each category introduces unique structural and waterproofing challenges.

1. Structural Glass Balustrades (Continuous Structural Channel)

Structural glass balustrades rely on a heavy-duty aluminium base track that clamps and cantilevers the glass. To achieve the required load performance, these systems typically require fixings every 200–400 mm directly into the floor.

Waterproofing Strategy (Pre-BalcoDeck®)

Because the track must be mechanically fixed, installers have historically drilled directly through the waterproof membrane. The attempted workaround is to fill each penetration with a polyurethane, silicone, or resin-based sealant.

This method relies on three vulnerable factors:

The sealant itself – its elasticity, ability to withstand ageing, UV, and thermal expansion.
The installer’s application quality – even a small void can allow water to track under the membrane.
The number of penetrations – dozens (or hundreds) of holes inevitably increase long-term risk and usually void the roof warranty.

Drainage & Fall Issues

Roof terraces are required to have falls—typically 1:40 to 1:80. Structural channels placed directly on a sloping surface must either:

follow the slope (leading to sloped glass), or
be packed/raised (creating inconsistent bearing and drainage gaps).

Installation on Decking?

Traditional decking (timber or composite on pedestals) cannot structurally support a structural glass channel. As a result, this category is effectively incompatible with decking systems unless fixed back to the primary structure—again piercing the membrane.

2. Post-Based Balustrades

These are the most common non-structural systems, using either:

Base-plated posts fixed through the membrane, or
Through-membrane posts installed before waterproofing, with the membrane later dressed around them.

Base-Plated Post Installations

Installation requires multiple fixings per post, each penetrating the membrane. Waterproofing relies on:

resin or PU sealant injected into the fixing points; or
a post-installed “umbrella” flashing—rare, system-specific, and complex.

As with structural channels, the risks include sealant failure, incorrect application, and warranty invalidation.

Posts Installed Before the Membrane

In this case, waterproofers attempt to dress the membrane around the post and sometimes apply a pre-formed “umbrella” flashing to deflect water. This method:

is highly specialised,
must be planned early in the build, and
is rarely used in refurbishments or retrofits.

Bottom Rail Considerations

If the balustrade includes a bottom rail:

fixing it directly to the roof reintroduces the same penetration issues and slope alignment problems,
fixing it to decking is possible only once the posts themselves are structurally anchored through the roof.

3. Hybrid® Handrail-Supported Systems (No Posts Required)

Some Hybrid® systems (Such as our Orbit or Aerofoil systems) can span several metres using the structural handrail fixed only at the ends (e.g., 3m out, 4m across, 3m back), provided these end fixings connect to solid walls.

Advantages

No posts mean no roof penetrations for the balustrade itself.
The bottom rail can rest on decking without structural load requirements.

Limitations

Only works in layouts where the handrail can be structurally anchored at both ends.
Not suitable for all terrace geometries or regulatory load requirements.