Attic

Attic:

• Vents: Your choices are gable, turbine, powered, or ridge. Most homes now are built with an ridge vent at the top of the roof, but the other vents are still in use. All that matters is that there is sufficient airflow to keep your attic within 20 degrees of the outside air. If it is 70 outside and 90 in your attic, you probably have enough airflow, but if its higher than that, you need to firstly check the intake vents along the underside of your eaves. Blow compressed air in them from the outside to clear any obstructions(usually blow-in insulation). If the vents are clear, you want to add a powered attic fan. You can use the wired kind or the more expensive solar powered versions, either way, 20 degrees is the target. Most powered fans come with a thermostat set to turn on at 90 degrees F. Here's an expert from an HVAC forum.

  The rule with attic ventilation is 1 : 300 with a vapor barrier and 1 : 150 without a vapor barrier. So if you had insulation in the attic with a vapor barrier and the attic was 900 sq. ft., you would need 3 sq. ft. of free venting. If it was blown in insulation without a vapor barrier, you would need 6 sq. ft. of free venting. This is when you have an equal amount of square footage of high and low vents ( gable and soffit). Your concern about attic fans is correct. The problem is not the fan but the over sizing of attic fans. Most attics can only handle about 1500 cfm of ventilation because of the vents. Your fan that you have probably moves about 2000 to 5000 cfm. In which case it could cause a problem with drawing air from the home and causing the problems you mentioned. Properly sizing the fans is important because of this. You could increase the size of the vents but you're looking at more than doubling the amount. You're much better off putting in the proper size fan. The volume of air in the attic remains constant. So if the vents only allow 1500 cfm and the fan moves 2500 cfm, it will seek to get the air from somewhere, like the home. If the fan couldn't get the air from anywhere else, you would just burn out the fan.

  So do the math, and either install more venting or get an appropriate sized fan. 


• Radiant Barrier: EVERY ATTIC NEEDS RADIANT BARRIER!!!!!
  Radiant Barrier (attic foil) blocks radiant heat from the sun from infiltrating the interior of the attic space. Radiant Barrier is usually stapled to the underside of the rafters. Radiant heat is bounced off the foil and back through your roof to the outside where you want it. This is the cheapest and most rewarding insulation job you can do if you have a hot house and don't already have radiant barrier insulation. Attic Foil Radiant Barrier provides a great product and is easy on your wallet.Best of all, it doesn't make you itch! 


• Insulation: FiberGlass or organic insulation either laid out or blown in is the next layer of defense. Fill or lay in insulation to the level or even higher than the ceiling joists. Buy as much (R-Value) as you can afford. Its a proven investment. But only marginally effective if not combined with radiant barrier. 


• Bathroom & Kitchen Fans: Make sure the baffles are working properly so that those vents are not leaking air to and from the attic when they are not in use. Look into replacing with better units.


• Attic Access: If you have an attic door in the interior of your house(not in the garage), Make sure it is insulated. If when closed, it is a different temperature than the rest of the ceiling, you need to insulate it. You can use a commercial product or simply aluminum foil, styrofoam sheets, and duct tape to get the job done.