In other words the entire vent opening doesn t count as vented space.
How to ventilate your attic.
Begin by making sure your existing system works photos 1 and 3 plugging major air leaks into the attic photo 2 and correcting any other of the common causes of poor attic venting.
Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.
If there are asphalt shingles on your roof the attic must be ventilated to comply with the terms of the.
Your actual living space is sealed.
Most come with a window kit for this purpose that attaches to a hose on the back of the unit.
Calculate net free vent space building codes typically require 1 square foot of venting space for every 150 square feet of attic space.
It s a standalone unit that s about two feet tall and 18 inches wide and has wheels for mobility.
A sign of roof leaks from ice damming or other causes.
Hot air exhaust vents located at the peak of the roof allow hot air to escape.
That said air resistance and interference such as vent grates reduces the area of true ventilation.
To properly ventilate an attic two types of vents are needed.
Once they are in place you can then place the batts or blankets or blow insulation right out to the very edge of the attic floor.
Look at your eaves and roof.
Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed.
Here are four signs of an unventilated or under ventilated attic.
If you have either ice dams or moisture buildup improve your attic ventilation.
If you don t see any attic vents on the roof or in the eaves you need to add some.
The venting space should be equally divided between intake.
A hot ceiling tells you that the attic is acting like a solar oven.
Intake vents which are located at the down slope edge of the roof aka eave s and allow fresh air into the attic.
Portable air conditioners do need to be vented to pump the hot air outside.
Don t avoid ventilating your attic for fear you re letting cold air into the house.
Obviously more research is needed but here s what we do know.
Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation.
Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.
Rafter vents should be placed in your attic ceiling in between the rafters at the point where your attic ceiling meets your attic floor.
You can also contact your local municipality to check on building code in your area.
