Ventilation Louvres

How do I achieve the correct attic ventilation?

The roof needs replacing. I’ve been told the gable vents (one at each end of the side walls) need to be blocked up. Is this correct? There are ridge vents along the top, soffits under the bottom edge of the roof, and another vent (like a flattened mushroom) extending out of the roof. Also, is there anything else I should watch out for or ask when I talk to the roofers? As you can tell, I don’t know much about this and I don’t want to get scammed. The main part I'm unclear about is if the existing gable vents (one at each end of the side walls) need to be blocked up (as I've been advised), taking into account the other vents that are there. I'd have thought the more vents the better, so would it be better to leave them open?

Public Comments

1. most houses with a ridge of 40-50 linear feet only need 4-5 vents. Put you have plenty of adequate venting for code. And if you have the ridge vent that is under your ridge cap your sittin perfect
2. Ask your circle of friends, somebody will know some body to help you thru this!!
3. I'm not aware of anything that prevents you from having gable vents - but balanced eave and ridge vents provide better ventilation; it may be that your local building authority requires this configuration. Depending on the pitch of the roof, the ratio of vent area to attic square footage is between 1-150 an 1-300. The higher the roof pitch, the more venting need per square foot (because the *volume* (cubic footage) of the attic increases with the pitch of the roof). Better to over-vent than under-vent. Insufficient venting can lead to a hotter house in the summer, and (if you're in snow country) ice dams in the winter.
4. You need the gable vents open or the (mushroom vent) which is actually an electic fan will create a vacuum in the attic. The heat is pulled out through the fan while the vents suck in fresh air. Make sure your fan is working. In North Carolina we set them at 90 degrees. The best way to tell if fan is working is to turn the thermostat all the way down, fan should come on. If it doesnt replace it. I charge 175.00 to replace fan or 225.00 to install a new one. Fans are sold at different speeds for different attics. Make sure the new fan is powerful enough for your attic. This info is generally printed on the box. The only thing that you should have to do to gable vents is Bat proof them with wire mesh.
5. where is your country? Tropical or western? You know, hot air goes up, cool air goes down. Im an arcitect in Iloilo City, Philippines. Send me actual pictures so our suggestions would also be accurate. My email add is arkitekgil@yahoo.com ,