Epoxy terrazzo is becoming increasingly popular in commercial environments because it is incredibly durable and long lasting, as well as being available in a wide variety of colours and aggregate blends, allowing for creative and totally unique designs. 

Its impact and wear-resistant qualities, as well as its easy of cleaning and maintenance and tailored slip-resistance properties, make it ideal for high traffic areas in commercial areas such as shopping malls, schools & universities, offices & hotel receptions, along with museums, hospitals, offices and airports.  

A polyurea membrane such as vebro UR Membrane can be specified under epoxy terrazzo systems, such as vebro Classic Terrazzo.  

What is a polyurea membrane?  

A polyurea membrane is a specially formulated liquid applied coating system that is applied beneath the epoxy terrazzo in order to create a flexible barrier between the terrazzo materials and the subfloor.   

A polyurea membrane is typically installed over two coats, with the first acting as the flexible layer and the second with a blind of aggregates that provide a mechanical key for the terrazzo. 

Why choose a polyurea membrane? 

In short, the primary reason for specifying a polyurea membrane below an epoxy terrazzo that is designed to last the lifetime of the building, is to reduce the risk of cracking mirroring through from below.  

Why is there a risk of cracking from below? 

With an unbonded or floating screed, there is a greater risk of movement leading to shrinkage cracking as the screed goes through its natural drying process. 

Where a screed is floating on insulation or a void former, either with or without underfloor heating (UFH), there is a risk of the screed cracking due to the floor being exposed to imposed loads greater than the compressive strength or density of the insulation that is acting as the vehicle to carry the screed and epoxy terrazzo system.  

Should the insulation compress more than 1.5 mm, there is a risk the screed will crack and mirror through to the terrazzo.  

The inclusion of UFH poses a greater risk from thermal expansion and contraction of the screed below as it goes through its daily heating cycles. 

How does a polyurea membrane help to reduce this risk? 

Installing a polyurea membrane creates a separating layer between the screed and the terrazzo. Typically exhibiting elongation of 800%, this greatly reduces the risk of any cracks from below reaching the terrazzo floor finish. 

While it is technically a separating layer, the polyurea membrane is still bonded to the top of the screed but separated from the terrazzo above. A thinner layer of polyurea is used to chemically adhere the flexible layer, with the top layer being blinded out with aggregate to provide a mechanical key for the terrazzo.  

It is important that the aggregate is not broadcast into the initial membrane as this will form a biscuit type layer and drastically reduce the flexibility of the membrane. 

While we’re focusing here on polyurea membranes under epoxy terrazzo, the waterproofing capabilities of this technology – combined with its flexibility and crack bridging properties – also make it ideally suited to multi-storey car parking structures and industrial environments alike. 

Vebro Polymers’ epoxy terrazzo system, vebro Classic Terrazzo, has been installed in a number of prestigious projects including the stunning Sunderland City Hall. Read more about the impressive installation here. 

Looking for specification advice on your next epoxy terrazzo project? Contact your local team today.