Premature aging of your roof material and high energy bills can be caused by improperly vented attics In the summer. It can lead to mold problems and even mildew and cause moisture to accumulate in your attic in the winter.
You will most likely get ten different answers if you ask ten different roofing contractors about roof ventilation. And chances are which ventilation seminars they have attended will not be told by one of those contractors.
Misinformed contractors are guilty of spreading some common ventilation myths that are:
The exhaust is doubled by installing low profile vents on both sides of a roof peak.
One side will actually push the warm air beneath them down against the attic floor and act as an intake for the other if you place the vents across the ridge from one another.
To the existing ventilation system you can add ridge vent.
Indefinable draft patterns can be caused by mixing different types of vents interrupting the free flow of air. Each other can be cancelled out by the different vent types. If ridge vent is going to be installed the low profile vent or existing turbines holes should be covered. You may also need the mould removal service.
Better is more ventilation. Not necessarily.
The conditioned air from the living area can be sucked by too much attic ventilation and the area may become counterproductive. 1/300 is the ratio accepted by the SBCCI, FHA, and UBC.
However, for warmer year round climates 1/150 is recommended. Between the exhaust and intake this number is then divided evenly. By this formula, thirteen square feet of ventilation is required by a 2000 square foot attic.
This number needs to be divided by two, 6.5 for exhaust and6.5 square feet for intake. Four feet of ridge vent or one wind turbine is worth one square foot of exhaust for reference.
You would need 7 turbines, 26 feet of ridge vent, and thirteen soffit vents for a 2000 square foot attic. You must prevent rising damp in Brisbane with adequate ventilation.
Power vents are the best thing out there.
With a thermostat, Power vents are heat activated and generally in the coldest months of winter allowing moisture to accumulate does not work to move air. The thermostats in the power vents usually break within the first two years and are very temperamental.
They run off of your electricity and they require an electrician to install, which makes them an ongoing cost. On the other hand, by far solar powered vents are superior products, and when installed correctly they possess none of the negative traits of the traditional power vents.
The roof vents are worthless without air intake, which is the most important thing to remember. Call a trusted local contractor for an estimate if you do not have any soffit ventilation or need rising damp treatment.
Ensure they are clear of dirt and insulation if you do have soffit vents. For a more creative solution you should ask a qualified roofing contractor if you have special circumstances such as open cornices or cathedral ceilings.