Turret or Gazebo Roof Venting:
Sadly turret and gazebo roofs are rarely vented. An open gazebo roof may not need venting as badly, but there is a huge misnomer about this issue concerning turret roofs; these roofs still need proper venting if you want them to last and be more comfortable inside.

The real reason they are not vented is only because of shear laziness of working that into the construction with all those rafter beams conjoining in the center. For a roof vent it requires a solution that will not leak even in stormy weather. Carpenters and roofers are not sheet-metal workers. They know nail-guns and saws. For some construction workers it is all they can do to read a tape measure correctly. Problem solving this issue is a foreign subject to them. It is a lot easier to just pretend venting is not needed, knowing that the homeowner a decade later cannot legally come back on them for their negligence.

The Best Solution (if it is not already built):
Few carpenters realize how much easier it would be to join the stringers over this strong octagonal channel made with 1' to 1.5' long 2x6 boards angle cut at 22.5 degrees on both sides and assembled into a hollow core to allow for around 100 square inches of vent through the center.

If at the time that you are reading this it is not already too late we can make you one of these in a kit or pre-assembles: glued and screwed together, then shipped to you for $75 to $150:

Shown here with a hammer to show size, and an 18V drill to show how easy
it would be to attach the roof joists from inside the center with deck screws.

Size Needed For This:
As long as the roof cap is large enough to cover the vent holes by a good 4" to 6" margin (depending on the roof angle), this is a good time to rectify this oversight and add roof venting at the top of the roof. You may also need to see what can be done about fresh air entering that attic space at the bottom, so that fresh air can heat up and rise out the top to draw in more fresh air from the bottom. It is easy to just mount a set of spacer blocks under any of our new copper roof cap designs (I wrote this out in detail on our Installation Instruction web page).

Appearances:
I feel it also makes the roof caps look better. Especially if they have a fancy tail design to them, but that is certainly a matter of opinion. When the copper tarnishes to a brown this graduation up off the roofing shingles gives the bottom edges a 3 dimensional distinction that is more easily seen from a distance. Some people might be concerned that bees will build a small hive up under this gap below where the screen is. That may be true, but bees with always find some place to build their hive on your property. At least this is way up high out of harm from children or guests.