Airtightness Membranes | INTELLO PLUS | Scholten Group
Airtightness Membranes and Intelligent Air Barriers
Why Airtightness Matters
An air barrier stops conditioned air leaking out of a building and unconditioned air leaking in. Three things follow from that.
Insulation works properly. Bulk insulation only performs if air is not moving through it. Air leakage through a wall can reduce the effective R-value of the insulation in it by a substantial margin, which means the insulation you specified is not the insulation you got.
Moisture stops moving into the structure. Air carries far more water vapour into a wall cavity than diffusion does. Sealing the air barrier is a more effective condensation control measure than any amount of vapour barrier on its own.
The building is more comfortable. Draughts, temperature stratification and dust ingress all reduce.
Airtightness is measured by blower door test in air changes per hour at 50 pascals. A typical Australian home tests somewhere between 10 and 20. The Passive House standard requires 0.6 or better.
How an Intelligent Air Barrier Works
A conventional vapour barrier has a fixed permeance. It blocks moisture moving into the structure, which is what you want in winter, but it also blocks the structure drying inward, which is a problem if moisture ever gets in.
An intelligent air barrier changes its permeance depending on the humidity around it. In dry conditions it stays closed and blocks vapour moving into the assembly. In damp conditions it opens up and lets the assembly dry back into the building.
The practical benefit is a margin for error. Buildings get wet during construction, roofs leak, plumbing fails. An assembly that can dry in both directions survives things that a sealed assembly does not.
The INTELLO Range
INTELLO PLUS is Pro Clima’s intelligent air barrier, reinforced for strength and using Hydrosafe technology to deliver the humidity-variable behaviour. It is suitable for walls, ceilings and roofs across all common construction types.
Available in 1.5m and 3m widths. Since 2024 the nonwoven layers contain 50 percent recycled content.
An air barrier is only as good as its seals. INTELLO is designed to be used with the TESCON and CONTEGA connection products, which handle laps, junctions, penetrations and window connections.
Airtightness and NCC 2022
The NCC does not currently set a numerical airtightness target for Class 1 dwellings the way the Passive House standard does. What it does require is condensation management, and the vapour control provisions in Part F8 apply to sarking-type materials and pliable building membranes on both sides of the assembly.
Beyond compliance, airtightness is where the energy performance actually comes from. A building can meet its NatHERS rating on paper and leak enough air to undo a meaningful share of it. Builders who are being asked for better performing homes usually find air sealing is the cheapest improvement available.
Questions About Airtightness
Is an air barrier the same as a vapour barrier?
Not quite. An air barrier stops air movement. A vapour barrier stops vapour diffusion. Many products do both, and an intelligent air barrier does the first consistently and the second variably.
Do I need an air barrier if I already have a wall wrap?
They do different jobs on different sides of the insulation. The external membrane handles weather and outward drying. The internal air barrier handles air leakage and inward vapour control.
Where does the air barrier go?
On the warm side of the insulation in cooler climates. In hot humid climates the answer is more complicated and depends on how the building is conditioned. Ask before you specify.
Can you retrofit an air barrier?
Yes, though it is more work. Retrofit airtightness usually focuses on the ceiling plane and service penetrations, where the biggest leaks are.
What airtightness result should I be aiming for?
Without a target you will not hit one. Passive House requires 0.6 ACH. A well built conventional home can reach 3 to 5 with reasonable care. Anything under 10 is an improvement on standard practice.
Find a Stockist
INTELLO PLUS and the Pro Clima airtightness range are available through stockists across New South Wales and South East Queensland.