Different Types of Roof Ventilation

There are different types of roof ventilation to choose between and it is their location on the roof that sometimes decides what type is best used. When it comes to attic vents and fans, you normally locate them in the highest corner of a gable, on the roof place or ridge or alternatively, underneath the eaves or soffit. In this article I will tell you a bit more about gable ventilators, ridge ventilators, roof plane turbines and fans and last but not least – the soffit ventilators.

Gable Ventilators

Gable ventilators are made of galvanised metal and are triangular in shape. They can be purchased at either a home improvement centre or at a sheet metal shop. Gable ventilators should be installed at the top of the gable and their purpose is to eliminate any heat that collects up by the house ridge.

Gable Ventilator

Ridge Ventilators

Everyone knows that heat rises and it is therefore not a surprise to learn that the hottest air collects at the highest point of the house – the ridge of the roof. Therefore, this is the most efficient location to place a vent. Ridge vent systems basically consist of long and inverted metal trough which allows air to leave the house easily and without taking in any rain. Remember to install ridge vents before you lay any roofing materials. I have mentioned this before but if you are doing any major work to your roof, try to deal with other roof related jobs at the same time. This could be work to with the gutters, chimneys, skylights and so on.

Ridge Ventilator

Roof Plane Turbines and Fans

The turbine vent is a clever invention. Once placed on the roof it acts in two different ways depending on weather. In calm weather they act as a free ventilation space whilst they generate an air flow when it is windy. When it is hot outside, you can avoid the need to use air conditioners by placing powered attic exhaust fans over ceiling vents. They work by increasing the natural air convection. If you are looking to purchase a normal exhaust fan, take into account its noise level and air flow. The airflow is calculated in cubic feet per minute or CFM for short. Noise levels on the other hand are measured in ‘sones’ where the lower the number, the quieter the fan is.

Roof Turbine

Soffit Ventilators

These ventilators are rectangular in shape and placed, as the name advises, at the soffit or by the eaves of the roof.  They provide an in-flow of cooled air whilst warm air convection draws the air upwards and through the gable and/or ridge ventilators. Another great thing with soffit ventilators is that they will assist in drying out the roof decks if they have leaked – especially by the eaves.

Soffit Ventilator

The Importance of Roof Ventilation

Roof Ventilation

Roof Ventilation

Did you know that breathing, cooking, showering and washing all add water into the air? It is believed to add between 5-10 pounds of water into the air in your home – every day! If you are washing and drying your clothes, you can add another 30 pounds of water on top of that. This moisture will condense once it reaches the attic and will cause damage to insulation, sheathing, rafters and if the moisture problem is really severe – it can even damage roofing materials made out of asphalt and wood. It is therefore very important that your house has adequate ventilation. Thanks to modern ventilation products such as attic fans and roof vents, you can allow the house to breathe, ridding the house of unwanted moisture. Good ventilation will also get rid of accumulated heat, fumes, smoke and vapours. If you are looking to improve the ventilation of your house, make sure to implement this when you are preparing the roof deck. Always try to deal with roof related work such as cleaning and repairing gutters when you are already doing work up on the roof.

Roof Ventilation System

Ventilation Needed

There are certain factors that decide how much ventilation a house needs. Things like sun, shade and wind direction has to be taken into account and the roof lines themselves can either encourage or interrupt the flow or air. A building inspector or a ventilation contractor can tell you what the ventilation needs of your house are and if need be, what size vents you need and where they are best placed. There are some rough guides about the amount of ventilation needed.

Roof Vent

Generally, 1 square foot of a free vent opening should be enough for 150 square feet of an attic floor. A free vent opening is an opening with no wire or grill-work taken into consideration. Remember that any wire or grill-work area will have to be subtracted. If your vent is covered by a wire mesh of 1/8 of an inch to ¼ of an inch, it will have to be about 1 ¼ times larger than a free vent opening. If your vent is covered by either 1/16 of an inch of insect screening or ¼ of an inch of mesh and a louver – make sure that the vent opening is twice as large. When it comes to the attic floor space, you can possibly get away with 1 square foot of free vent opening for about 300 square feet, providing you have vapour barrier installed. The vapour barrier has to be on the ‘room side’ of the insulation. Also, half of the vent space should be close to the gables tops or alternatively, along the ridges. An attic fan is a good idea if the natural venting is not enough to push hot air through the vents.