Traveling_Carpenter t1_j9wehru wrote on February 25, 2023 at 1:08 AM

Venting roofs doesn’t really make them cooler. The shingles and sheathing are going to be roughly the same temperature vented or not, and that heat is going to radiate into the space. You might experience a sensation of coolness from the air movement on your sweaty skin, which will bring some relief. A radiant barrier below your rafters would likely do more than venting will to make it feel cooler. If you have a window, open that along with the garage door to get a cross breeze when you’re in there.

DoItYourSelf2 t1_j9whgl7 wrote on February 25, 2023 at 1:31 AM

I put in a radiant barrier in my attic and I verified attic temp reduction of 20F at the insulation. Best $100 I ever spent.

True that it only reduces upstairs living space about 5 deg but that's misleading. It basically eliminates evening heat soak. Before house actually got hotter from about 5pm onward. The other advantage is that before if I turned on AC at 3pm, it would basically never make any headway. Now I turn it on at 3pm and 30 mins its almost at the thermostat setting because my evaporator and ducting is in attic.

When temps are above 85f my neighbors turn on AC at 1pm and they run pretty much constant whereas I almost never use AC anymore unless there is a string of 100 deg days which is rare.

I considered attic fan (I have a big gable vent) and came to same conclusion that they don't really work. Ridge vent is better but also has issues.