From the outside, a VPM membrane is a VPM membrane is a VPM membrane right? They all look pretty much the same and the manufacturers tell you they do the same thing. Which they do… but like so many other things in life, is not the what the matters, it’s the how.
The short answer to the above question is that the Solitex range has an engineered TEEE (Thermoplastic Elastomer Ether Esther) mid layer which makes them unbeatable.
See image to the left to see what this looks like. For the longer answer, read on!
TEEE? What on earth is it.
It stands for Thermoplastic Elastomer Ether Esther and is an engineered mid layer within the Solitex membranes which (when installed with the Extora tape range and according to the guidelines) makes them:
- air tight
- water proof
- vapour permeable (class 4)
- UV resistant for 180 days (138 days longer than some other membranes); and
- Tolerant of temperatures up to 100 degrees (20-30 degrees higher than some other membranes)
This state of the art system will reliably protect your structure for decades to come.
How does TEEE work?
The TEEE film has a monolithic internal structure as opposed to microporous internal structure which means, unlike other WRBs on the market, the Solitex membranes have no pores. Microporous membranes are generally manufactured from a vapour closed material such as Polypropylene (PP) or Polyethylene (PE) which are modified via stretching, perforation or spin bonding. This opens up the material and makes it porous which enables the vapour permeability (via convection) but in the meantime, this process can compromise the air tightness and, in the case of the perforated membranes, also the water tightness.
A TEEE film has no pores – it relies on active vapour diffusion rather than convection which results in a quicker drying time and lower condensation risk. In addition to this, the TEEE film is very durable when exposed to surfactants (chemicals that encourage water absorption). Microporous membranes, on the other hand, start out waterproof, but this can easily be compromised if the membrane comes into contact with oils or other contaminants found on site, putting your structure at risk.
So why does having this membrane even matter?
Moisture within a building is created in 3 main ways:
- Moisture in the timber trapped during construction
- Off gassing from paints and new materials when a house is newly completed
- Human occupation from cooking, breathing, showering, washing etc
In older, leakier buildings, this moisture gets out through the gaps and cracks in the house around doors, windows, electrical and plumbing penetrations, behind skirting and cornice, the list goes on. There are tonnes of pathways for moisture to escape in the current Australian housing stock. Moisture in leaky houses is not generally a problem (unless there’s a concentrated humidity issue in an improperly ventilated wet area for example, or an unaddressed water leak) however, as regulations increase over the 2022 and 2025 NCC updates (and beyond) and awareness of energy efficiency and air tightness increases, the internal and external conditions will become more at odds with one another. There will be increased indoor humidity due to less air leakage and larger indoor / outdoor temperature differences due to increased insulation. These two factors combined mean that there is an increased condensation and mould risk that needs mitigating.
The vapour that builds up inside a building has to get out somewhere and if it can’t get out easily through the gaps and cracks, it will continue to move through the vapour permeable layers of the wall until it either
- safely condenses on the external surface of a Weather Resistive Membrane / Vapour Permeable Membrane and dries or drains away within a ventilated cavity; or
- gets stuck behind a vapour impermeable surface and creates a mould problem inside your wall.
So which kind of membrane is best for your project. The one with the magic TEEE mid layer, or one of the other, far less durable products…?
Visit our website to download our takeoffs guide so you can calculate how much product you need on your next project and then drop me a line to make your order! 0409 404 924. Talk soon!