Waterproofing Warranties and Roof Terrace Balustrades: What You Need to Check

A waterproofed flat roof is designed to provide a continuous barrier protecting the building beneath. When that roof becomes a terrace, however, another requirement is introduced: the balustrade must be structurally secure.

Traditionally, this has often meant fixing balustrade posts or channels through the waterproofing layer into the structure below.

That detail deserves careful consideration — particularly where a waterproofing warranty is already in place.

Can balustrade fixings affect a waterproofing warranty?

They can.

Waterproofing warranties relate to a particular roof system, installation and set of conditions. Introducing a penetration after the membrane has been installed can alter those conditions.

That does not mean every penetration automatically invalidates every warranty. Different manufacturers and warranty providers have different requirements.

However, penetrations may need to be approved by the waterproofing manufacturer, designed using an accepted detail and completed in accordance with its installation requirements.

The important point is simple:

Do not assume that a waterproofing warranty automatically covers subsequent penetrations made to install a balustrade.

Check before the detail is specified or installed.

Five questions to ask before penetrating a waterproof membrane

Before approving a penetrative balustrade detail on a roof terrace, establish:

1. Who issued the waterproofing warranty?

Identify the membrane manufacturer, roofing contractor and warranty provider, where applicable.

2. Does the warranty permit penetrations?

Check the actual warranty terms rather than relying on assumptions about what is normally accepted.

3. Does the proposed penetration require prior approval?

Some systems may require penetrations and associated detailing to be agreed with the manufacturer or warranty provider.

4. Who is responsible for the waterproofing around the fixing?

Establish who designs, installs, inspects and warrants the interface between the balustrade fixing and waterproofing system.

5. What happens if water ingress occurs later?

Make sure responsibility is documented. If the membrane was installed by one contractor and subsequently penetrated by another, establishing responsibility for a future leak may become more complicated.

Why the interface matters

A waterproof membrane performs as a continuous system.

Once a penetration is introduced, waterproofing at that point depends upon the detailing used around the fixing. Depending on the system, that may involve proprietary collars, flashings, seals or other manufacturer-approved components.

Those details can perform successfully when correctly designed and installed.

But they introduce an additional interface into a roof build-up that may subsequently be covered by decking, tiles or other terrace finishes.

That matters because the waterproofing layer can become difficult to inspect once the terrace is complete.

Think beyond practical completion

A roof terrace can appear completely successful at handover.

Waterproofing issues may not become visible until much later, after the membrane and fixing interfaces have experienced weather, thermal movement and normal building movement over time.

If water ingress does subsequently occur, determining whether the cause lies with the original membrane, a later penetration or the detailing around it may require investigation and potentially removal of terrace finishes.

For architects, developers, contractors and property owners, the question therefore should not simply be:

“Can this detail be made watertight today?”

It should also be:

“What does this detail mean for the waterproofing system, warranty and responsibility over the life of the terrace?”

Can the penetration be avoided?

Yes.

A roof terrace balustrade does not inherently have to be mechanically fixed through the waterproof membrane.

BalcoDeck® was developed to provide an alternative approach.

The patented system uses an engineered substructure positioned above the waterproofed roof to support the deck and balustrade without requiring penetrative balustrade fixings through the membrane.

The roof membrane can therefore remain continuous beneath the terrace system.

This removes the need to introduce balustrade fixing penetrations into the waterproofing layer and avoids creating that additional interface between the balustrade installation and membrane.

Protect the membrane. Protect the warranty position.

For an existing waterproofed roof, the safest starting point is always to establish exactly what the warranty permits before any work takes place.

Obtain the warranty documentation, identify the waterproofing system and speak to the relevant manufacturer or warranty provider where necessary.

Where penetrations are proposed, obtain approval for the specific detail and document responsibility for the work.

And where a non-penetrative solution is technically appropriate, consider whether the penetration needs to be introduced at all.

Planning a roof terrace?

BalcoDeck® provides an integrated non-penetrative deck and balustrade system designed for waterproofed flat roofs and roof terraces.

Talk to the BalcoDeck® technical team about your project.

 

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