|Cavity wall insulation solutions are coming under greater scrutiny as they gain popularity with the transition to 6-Star energy efficiency requirements.
Leading insulation innovator, Kingspan Insulation, urges consumers, regulators and the building industry itself to be mindful of the insulation products being installed in cavity walls.
According to Kingspan Insulation Technical Manager, Mr. Keith Anderson, some products currently being used may not be compliant with the Building Code of Australia (BCA).
“Products that fill the cavity in a double brick wall, such as "full-fill" insulation systems, potentially contravene the building code deemed-to-satisfy provisions for weatherproofing which requires the wall to comply with AS 3700 Section 4.7 Prevention of water penetration,” he says.
“The reason for this reference is to prevent moisture ingress migrating across the cavity to the inner wall.”
Clause 4.7.1 of this standard states that ‘In cavity walls and masonry veneer walls, cavities with a minimum width of 40 mm, which are properly detailed and constructed, shall be regarded as being resistant to the passage of moisture from the exposed face through to the inner, unexposed face of the wall’.
This poses a potential problem for insulation systems that fill the cavity, according to Mr. Anderson.
“Clearly, a ‘full fill’ insulation system, where the insulation fills the full width of the cavity and is generally ‘blown’ into the cavity, potentially provides a possible channel for moisture to bridge across the cavity, particularly if any variability of density or inadequacy of coverage is present”.
Mr. Anderson says excessive moisture can have serious health-related side effects for a building.
“Moisture problems and undue dampness can lead to mould growth, which can ultimately impact the indoor environment quality of a home and can even cause structural damage.”
Kingspan Insulation has released an innovative insulation product designed specifically for cavity walls.
“We’ve developed Kingspan Air-Cell Permicav® as an all-in-one insulation and vapour-permeable membrane designed to allow water vapour transfer, at the same time providing a water barrier and cavity while thermally helping to achieve 6-Star energy ratings,” says Mr. Anderson.
At an ultra-thin 5.5mm profile, Kingspan Air-Cell Permicav® is an ideal solution to fit into the cavity of double brick walls without filling the cavity space, according to Mr. Anderson.
“Depending on a few variables, Kingspan Air-Cell Permicav® cavity insulation could deliver up to a full star rating in your house energy efficiency ratings, possibly taking you from a 5 Star house to a 6 Star house,” he adds.
Mr. Anderson says that the vapour-permeability of the product is a unique feature.
“The perforations in Kingspan Air-Cell Permicav® allow water vapour to permeate, thereby preventing a build-up of moisture in the cavity by allowing it to escape.”
Cathy Inglis, Group Technical, Research and Engineering Manager of Austral Bricks, Australia’s largest brick manufacturer, says Permicav® is perfect for cavity walls.
“We’ve tested a lot of insulation products for cavity walls and have found Kingspan Air-Cell Permicav® to be ideal for this construction. Its thin profile means the wall cavity isn’t filled, which is really important for BCA compliance. And what’s particularly unique about Permicav are its perforations. It’s designed to be vapour permeable, helping to reduce the risk of condensation occurring within the cavity.”
Kingspan Air-Cell Permicav® is manufactured with a patented cross-linked, closed-cell structure sandwiched by highly reflective perforated foil.