Does adding a ridge vent to your roof cool down your attic? Does that vented attic help cool down your house? Let us help you determine if adding a ridge vent to your roof is worth the effort.
First off, use caution when working on a roof. Some newer construction houses have eyelets installed on the ridge so you can clip a safety harness into the structure. With that said, the whole point of this project is to ventilate the attic space above my kid’s upstairs room. The problem we are attempting to solve is the trapped (or poorly vented) hot air trapped in the attic. Most houses in the US have pitched roofs with insulation placed above the ceiling joists. The other alternative is to spray insulation or place insulation batting in the pitched roof joists.
Either way, in the summer time, the uninsulated area above the ceiling insulation can get very hot. In a lot of cases, this is the area that air conditioning systems are housed or at least ducting is ran. If this hot area is vented better, it would help the insulation on the ceiling joists and the protected AC lines. That’s the theory anyway, we’re going to test it.
Most pitched roofs have vented panels under the eve, or overhang, called soffits or soffit vents. These slatted vents allow fresh outside air to move through the attic space to fend off mold and moisture. The problem with our house is the soffits alone are creating a convection oven effect in the attic making the rooms below it very hot. By creating an opening along the roof’s tip ridge, the hot air can escape, hopefully cooling the space.
While on the roof, locate the top ridge and the overlapping shingles (if you have shingles) that run alone the length of the roof. Carefully pry those shingles off so you can reuse them later. Once removed, you will see the black barrier that protects the plywood sheeting. Underneath this sheeting are the roof joists you can see from inside the attic.
Using the measurement from the ridge vent kit, mark a line down from the ridge with a chalk line. Now, set your circular saw cut depth equal to the thickness of the plywood sheeting, usually 3/4″. Cut along this line, leaving about a foot from the ends of the roof line. After peeling this sheeting off, you should be able to feel the hot air escaping from the attic below.
Now that you can see the tips of the roof joists and the open spaces between them, it is time to roll out the plastic ridge vent cap. The plastic roll is designed to be nailed down to the joists while leaving an open venting space underneath. Be sure to use roofing nails when attaching this ridge vent system. It would go really fast if you were to rent an automatic roofing nailer.
Lastly, it is time to add the shingles back over the plastic vent. I attached them using the same roofing nails that I previously used. Make sure to use the guideline on the ridge vent when attaching the shingles. If you need to add any transition shingles, you can adhere them with a special roofing adhesive and more nails.
But Does It Work?
I took baseline temperature measurements before we started. The temperature outside was 93℉ (33℃), the attic was 120℉ (48℃), and the bedroom below was 81℉ (27℃). I took several temperature readings over the course of a week after we finished the vents. The 6 days following the work averaged 91℉ (32.8℃), I was surprised that the attic averaged 10 degrees cooler than the baseline reading. I was hoping that this consistent cooling would have an effect on the room.
The room may have underlying insulation issues, but I didn’t find any change in temperature from the baseline. After checking the ducting and replacing some insulated AC lines, the room has not cooled because of the ridge vent. So, here are my final thoughts: If you are getting your roof replaced, have the installers add a ridge vent. If you are dead set on doing it yourself, it was very manageable as a DIY project but didn’t yield noticeable results after a week of monitoring.