Don't want to get soaked....by roof vent

Hi All -

So last year I built a shed that incorporated a second story playhouse for my son. I'm rather proud of it.

It's a solid, water-tight build all around. Power and lighting on both levels with finished flooring.

Here's the thing. In summer this thing gets cooking hot. Even with the front and side windows it just seems to trap hot air. I want to give it better ventilation both for comfort and to mitigate any mold growth.

I was going to pick up one of those whirlybird turbine roof vents, thinking it wold move a lot of air.



Now, I've built a number of roofs in my time but never used one of these vents. I'm puzzled by one thing...What keeps the rain out? I mean it's a stack jut sitting on a base...topped with the vent that may or may not be spinning depending on the wind.....So what's to stop all kinds of water from entering?

I'm very interested to hear from those who have had experience with these...

Here's the shed [slash] backyard condo

Attached Images