How to install a roof vent

How to install a roof vent

Roof ventilation is a great way of relieving the build up of heat within the roof space of your home. Heat build up increases the inside temperature of the home as very hot air is trapped and the heat transfers through the ceiling to inside the home. Insulation plays a major role in stopping heat from the roof space radiating through to the inside of the home. However a roof vent lowers the heat build up by extracting the hot air and pulling in cooler air. This makes the insulation more efficient and able to block the heat more efficiently thus resulting in lower inside temperatures.

Types of Roof vents

  • Wind powered: Rota vents or Whirlybirds rotate as the wind blows and extracts air with an internal fan.
  • Electric powered roof vents: these are powered by mains power and have a thermal switch that turns the fan on if the roof cavity gets above a set temperature.
  • Solar powered vent: These are similar to electric powered vents but have a small solar panel on them or with them that powers the fan. Result: cost nothing to run and has much more air flow rate than wind powered vents.
  • Static Vents: These types of vents are not powered and are installed to the top of the roof and let out hot air. They work on the principle that hot air rises and the eve vents let in cooler air. These are better than no vents but are inefficient and do not exchange a lot of air.


Installation instructions come with these vents which will tell you the size hole that is needed. It is also important to install the vent near as possible to the top or apex of the roof. As hot air rises the hottest air moves to the top of roof and then is exhausted out and cooler air comes in under the eaves.

How to install a roof vent

Step one:

Make the hole at the correct size as per the instructions, near the top of the roof. For metal roofs you will need to cut a hole through the roofing using a cutting tool (jigsaw, tin snips, and non sparking metal cutter). A grinder is not recommended because sparks may enter the roof cavity which is a fire danger. Also the danger of using a grinder while trying to stay on the roof. Then cut away any insulation so you have a clean hole through to the roof cavity.

For tile roofs carefully remove as many tiles as needed to get the correct hole size and position so the flashing can side up under the tile above the vent. You may need to cut your tiles to get the right sized hole. This is best done on the ground with a small grinder with a stone cutting disk. Cut away any insulation between the tiles and the roof cavity.

Step two: Fix the vent in place:

for metal roofs the vent is screwed down and sealed at the same time. So make sure the vent fits and then run a bead of silicon sealant around the hole and around the base of vent. Then screw into place and check that the vent is secure and sealed. If you have a wind powered vent you will need to adjust the vent level because of the slope of your roof and secure the adjuster on the side of the vent when this is complete.

For tile roofs:

if you are able, screw into the roof trusses and then fit the tiles around the vent and seal with silicon. Then carefully bend down the lead flashing the make sure it is fully sealed and under the tile above the vent to prevent water entering the roof cavity.

If you have an electric powered roof vent have your electrician supply power to the vent and connect it. For wind powered and solar, your vent is finished and you are ready to install your eave vents.

Step three: Install your eave or soffit vents:

Install two to three snap in vents under the eaves or the soffit per roof vent. There are many different sizes of snap in vent available at your local hardware store. Just cut a hole to the size of the template and snap the vent in (no screws needed). Be sure that hole is clear of insulation and can supply air straight into the roof cavity. Drill a 12mm hole after the template has been marked and then jigsaw the hole out and install your vent. Be careful to use a dust respirator and do not grind the soffit lining as this will create harmful dust.

You roof ventilation is complete and now you have lowered the temperature of your home and this means better comfort and saving money. Your air conditioner does not have to work as hard and there is no trapped heat in your ceiling space.

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