In extreme climates like those we experience in Australia, every aspect of the design of a roof affects its behaviour and performance. Unfortunately, the local building industry is behind the pack when it comes to adopting new building trends.
Above-sheathing ventilation is a perfect example of this, as the current status quo in Australia is for roofers to use wet ridges that leave little room for ventilation. How does this create problems?
In an attic without above-sheathing ventilation, the warmth generated from solar radiation and interior heat loss have nowhere to go. As a result, they are passed through into the living quarters of the house. By adding more heat to an already blistering Aussie roof, energy costs climb, and the comfort of the tenants fall.
There is a long list of other problems that go along with those too. Trapped moisture turns to mould, which can harm the health of occupants. The materials the roof is made of are also under more stress, which causes them to deteriorate faster, and require more maintenance.
So what about roofs with above-sheathing ventilation?
In a study by ResearchGate, engineers found that the attic floor of a roof with above-sheathing ventilation was exposed to 70% less heat flow penetration. As you can imagine, this leads to a significant drop in temperature, increased energy savings, and less trapped condensation.
Beyond the natural above-sheathing ventilation created in tile roofs, products such as RapidRidge can be used to boost the thermal performance of your roof. Adding counter battens, raisers, and ventilated ridge systems will all promote additional airflow, cooling, and moisture resistance.
How Does Climate Effect Performance?
Above-Sheathing Ventilation in Hot Climates
In climates that are hot and dry most of the year, like Australia, above-sheathing ventilation is incredibly effective.
By providing a layer of ventilation, the heat that enters the attic space through the roof can quickly escape. The result is a passive cooling system that keeps the house cool and decreases energy use without the need for mechanical parts whirlybirds.
Above-Sheathing Ventilation in Cool and Humid Climates
One of the impressive things about above-sheathing ventilation is that it benefits the house and tenants in all climates.
Even in cool and humid climates, moisture-laden air can escape the attic space via the added ventilation. This is not the case when the roofing materials are fastened to the raised batten, as the air and moisture are trapped inside.
Above-Sheathing Ventilation in Cold, Snowy Climates
While most of Australia is fortunate to be ice-free, some folks in NSW will be painfully familiar with the reality of ice dams. On roofs that do not use above-sheathing ventilation, snow and ice can build up causing ice dams. For homeowners and tradies, there is no phenomenon more damaging than ice dams.
Ready To Change The Way Australia Builds?
Architects and builders are the gate-keepers of the Australian housing industry, determining which products are used, and which aren’t. Now that you’re an expert on above-sheathing ventilation, we hope that you’ll consider using RapidRidge on your next project. Trust us, Australia will thank you for it!