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I've installed ridge vents (ridgevent II) and am preparing to cap them with asphalt shingles.

As we all know, Phoenix AZ is hot...

These vents were installed hot, with no space between them. In the am, at about 60 degrees, they are about 3/8 to 1/2 inch apart.

I am not a physics major, nor a son of a physics major, but that movement over time seems as though it would take a toll on the ridge cap shingles. All that movement will increase the hole size around the nail. At the same time all nails are covered. Should be fine? thanks
 

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I instaled ShingleVent IIs last weekend, and have also noticed a surprising amount of movement. Shinglevent II instructions call for a 1/8" gap when installed in "cold weather" (no temperature spec for "cold" given in the instructions). Since it was in the mid-80's here in the San Antonio area at installaltion time, I left a 1/16" gap. I went back up the next morning to install on another ridge (I have 3), and was surprised at the gaps between the vents I installed the previous day. I would expect some thermal expansion/contraction, but not nearly as much as what I saw.

Like HappyArizonian, I'm wondering about this. Why did they move so much, and are they going to move more? What are the implications for the cap shingles and sealant (architectural shingles, so sealing is recommended in instructions)? They've already pulled away from the sealant on the ends - should I use something other than Geocell 2300?

Since they are in similar conditions, I'd really like to hear from any pros where summer daytime temps frequently get to 100 - but all insight is welcome, of course!
 

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Jus my own observations, but we have not had any issues where the shingle ridge caps have come loose due to any expansion and contraction.

But, mind you that we always use 2 1/2" to 3" hand roofing nails with all of our Shingle Vent II Ridge Vent and Ridge Caps over the Ridge Vents, which holds down significantly better than any shorter nails used.

FYI: Chicago Area, where temperatures change from extreme cold to extreme hot, but not as hot as Arizona obviously.

Ed
 

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How much contraction/expansion do you see? When I installed last weekend, I left 1/16" or less between sections. Now there's a 1/4" gap. That seems very odd. (I need to measure the overall length of the sections and see if anything changed there).

(I am using 3" nails, by hand, for my ridge caps.)
 
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