Jackson Digney explains why flat-roofed homes in the Adelaide Hills trap moisture in roof cavities, leading to mould and rot. Moist air rises, condenses on cold surfaces, and without ventilation causes structural damage. Adding building membranes costs $4,000–$6,000 but prevents far costlier repairs.
How to avoid condensation and mould in architectural flat roof homes. Sometimes, like when the area has strict height restrictions, flat roofs are unavoidable. But more often than not, they are an intentional design feature. For example, a home can be designed with a flat roof to achieve a particular architectural appearance inside and outside. Maybe the homeowner wants to utilise the roof space for an entertaining or garden area, or perhaps it's a case of economics. Flat roofs use less material and can therefore be cheaper to construct sometimes. With the growing popularity of flat roof homes, many Adelaide Hills homeowners are suffering issues with condensation and mould. Why so many flat roof homes have moisture and mould problems. All homes emit hot, moist air into the roof cavity through bathroom exhaust and through general living. This air rises through the cavity, then collides with the inside of the roof above. When the temperature of the roof is colder than the air, condensation can form. Without proper ventilation, this condensation can cause mold to grow throughout the roof cavity and even penetrate the gyprock in your ceiling. Excess moisture can also cause timber rot or steel rust in the structure of your home. The result is an unhealthy home that can become structurally unsound. Traditional high-pitched gable roofs have large roof cavities, space above the ceiling. This offers more drying potential as a result of either the ventilation of the space or management of moisture via high-performing building materials. Flat roof homes have much smaller roof cavities with less air movement and less chance to dry the air before it condenses on the inside of the roof. This greatly increases the chance of moisture, mould, and over time, structural damage. How to avoid moisture and mould In flat roof homes, the easiest way to avoid moisture issues is design your home with a steep pitch and a large roof cavity. Most homes that are 100 or more years old have high roofs. They last a long time because the air in the roof cavity has time to dry out without condensing, and therefore there is no mold and the timber structure remains dry. If a flat roof is unavoidable, because of height restrictions or architectural preferences, there are things you can do to minimise moisture issues. The addition of extra building membranes inside the roof cavity, on top of the ceiling, and underneath the roof reduce the transfer of moisture. Installed properly, this can greatly reduce and even eliminate moisture issues in flat roof homes. The cost to avoid moisture issues in flat roof homes. The cost to fix moisture issues in a home, especially a flat roof home, can be huge, and in some cases the problems simply cannot be fixed. However, precautions like extra membranes that reduce and in most cases eliminate these issues can be installed for just $4,000 to $6,000 depending on the size of your home. If only Adelaide Hills flat roof homeowners had known this, they could have avoided the moisture issues that compromised their health And the longevity of their homes. Avoiding moisture issues in a flat roof home requires specialised knowledge and experience in design, product choice, and installation. Whether you're ready to build or still looking at your options, one of the best things you can do is pick up a copy of our special report, The 5 Key Skills of an Energy Efficient Builder. We'd be glad to show you examples of homes that we've built to last. We will go through the design elements, workmanship details, and all the costs and options with you. Yeah.
