Penetrative vs Non-Penetrative Balcony Detailing

GB2636232

UK patent for the non-penetrative anchorage method

Zero

penetrations through the waterproofing membrane

A1 / A2

fire-rated build-up, suitable above 11 m

10-year

guarantee, from a single UK manufacturer

The real failure point

Terrace leaks start at the fixings, not the membrane

In conventional construction, balustrade posts, deck supports and guardrails are fixed straight into the structural slab. That means drilling through the waterproofing and relying on collars, sealants and flashings to keep water out.

Membranes outlast their sealsMany membranes are designed for 25 to 30 years. The sealants protecting each penetration work on a much shorter lifecycle.
Movement works the interface looseThermal movement, UV degradation and the lateral force of wind on the balustrade gradually work away at every sealed joint.
Failures stay hiddenWhen a joint fails, it is often concealed beneath the decking. Water can be entering the structure below long before anyone sees it.
The terrace sits over habitable spaceMost modern roof terraces are built directly above rooms. The membrane is now part of the roof, so its integrity is critical to the whole building.

How BalcoDeck works

Loads carried across the roof, not through it

BalcoDeck was developed to solve one dilemma: balustrades need to be held structurally, but drilling for them compromises the waterproofing. The system resolves both at once.

An engineered substructure spreads the loadStructural forces from the guarding are distributed across the roof, so the balustrade meets its guarding requirement without an anchor through the slab.
The membrane is never brokenNo collars, no sealant rings, no flashing details to maintain. The layer that keeps the building dry is left exactly as the waterproofer installed it.
It adjusts to the roof you haveThe support feet accommodate roof falls, so the deck sits level over a drainage gradient without packing or shimming on site.

Compare the two details

Not sure your roof detail suits a non-penetrative system?

Send us the roof type, size and project stage. Our technical team will tell you honestly whether it is worth surveying.

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Penetrative vs non-penetrative

The same terrace, two very different lifecycles

Detailing question	Penetrative fixing	BalcoDeck non-penetrative
Waterproofing membrane	Drilled through at every post	Left fully intact
Long-term watertightness	Relies on collars and sealants ageing faster than the membrane	No sealed penetrations to fail
Where a failure shows	Concealed beneath the deck, often unseen for years	No penetration to leak
Roof falls and drainage	Packed or shimmed on site	Support feet adjust to the gradient
Membrane warranty exposure	Membrane modified after installation	Membrane unmodified

Real terraces, membranes untouched

BalcoDeck is manufactured in Surrey by Balconette, a long-established UK maker of glass balconies and balustrades.

“Instead of drilling through the membrane, the system transfers structural loads through an engineered substructure that distributes those forces across the roof. This lets the membrane stay intact while still achieving the structural performance required for guarding.”

Effi Wolff, founder of Balconette and creator of the BalcoDeck system

Designing for the long term

Compliance at completion is no longer the whole question

Clients, investors and regulators increasingly ask how a building will perform over decades, not just at handover. For balconies and terraces, that means questioning whether a traditional penetrative detail is right for a long-life building. A detail that leaves the waterproofing whole is easier to stand behind for the lifetime of the roof.

BalcoDeck pairs the installed system with a single point of responsibility for the guarding and the roof interface, so the structural performance and the membrane integrity are covered together rather than split across trades.

Common questions

What specifiers ask us first

Yes. The structural loads from the guarding are transferred through an engineered substructure that distributes them across the roof, so the guarding requirement is met without an anchor fixing through the slab.

Because nothing is drilled through the membrane, the waterproofing is left exactly as installed. There is no post-installation penetration for a membrane manufacturer to exclude or query.

Yes. Because it sits on top of the finished membrane rather than fixing into the structure, BalcoDeck suits terraces where the waterproofing is already complete.

The support feet adjust to the drainage gradient, so the deck finishes level over a roof that is laid to fall.

Free suitability check

Find out if your roof can carry a BalcoDeck terrace

Not every flat roof is a candidate, and we would rather tell you that early than sell you a survey you do not need.

1. We read your detailsRoof type, size, access, project stage and postcode tell us most of what we need.
2. A quick technical callOne of our team confirms the roof is a sensible candidate and answers your questions.
3. Survey and fixed quoteIf it stacks up, we survey the roof and turn it into one fixed price, with no obligation to proceed.

Technical points on this page are drawn from Balconette's own article, Penetrative vs Non-Penetrative Balcony Detailing: A Lifecycle Design Question. BalcoDeck® is a non-penetrative roof terrace and glass balustrade system manufactured in Surrey by Balconette. UK Patent GB2636232.

A terrace worth building is a membrane worth protecting

Send us your roof details and find out, honestly, whether BalcoDeck is the right detail for your project.

Check your roof's suitability Call 01342 437411

Keep the membrane intact for its full life. Fix the balustrade without drilling through it.