Renovating a pre-1980s weatherboard home: what about condensation?

A significant portion of Australia’s housing stock comprises weatherboard clad lightweight framed buildings, which have nil or limited envelope insulation. With the reported appearance of condensation and mould in new and old housing, this project sought to explore the condensation risk that may arise from retrofitting insulation into existing uninsulated housing. A typical house from Victoria was selected and many variations of floor, wall and ceiling insulation, glazing and building sealing were explored. A cost benefit analysis was used to establish three built fabric typologies, namely; as-is, current code-compliant with some improved glazing, and better than code insulation and improved glazing. Each of these typologies was simulated using NatHERS software to produce calculated temperatures for each room. The simulation data were used to complete a software based condensation risk analyses. The simulations results show that some walls present no condensation risk, whilst others showed a significant risk.