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

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Old 05-28-15, 08:06 PM
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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.

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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

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Old 05-28-15, 09:02 PM
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Please tell me that the black wire is not the overhead power line.

I have no experience with that type of vent, but word around here is not favorable.
 
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Old 05-28-15, 09:25 PM
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With no over hang and no soffit vents you may be better off with two gable vents.
 
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Old 05-28-15, 09:30 PM
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I have one. Been there since about '82. No rain intrusion that I know of.Not a lot of venting unless windy imo. Always like the sound on a windy day though. Makes you feel like it's nice to be sheltered.
 
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Old 05-28-15, 09:58 PM
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Some companies will admit that high winds of 60 mph or more may allow "some" water intrusion. They generally don't leak because of a combination of factors- the angle of the louvers, the multiple ribs that direct runoff downward, the bulbuous shape- compare the side of the ductwork with the size of the louver- (any water that might get in through any of the gaps in the louver is NOT directly over the ductwork below because of the bulbous shape- a raindrop would have to enter the louver and then take a right hand turn in order to go down the ductwork) centrifugal force forces runoff to the outside of a spinning object, and any runoff heading downward inside the louver terminates on the outside of a flange since the bearing that allows it to turn is mounted OVER the ductwork.

They are more likely to leak from improperly roofing around them than from rain entering the louvers.

Having a continuous ridge vent would be my first choice. Hot air rises, so let it out. Its not like you need soffit vents for a ridge vent to work.
 
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Old 05-29-15, 06:45 AM
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No. The black wire is TV cable. All our power lines our burried.
 
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Old 05-29-15, 06:53 AM
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Thanks all. Gable or cap vents were my first thought but I wanted to consider something that was a bit more active.

X-Sleepers explainafion seems to suggest that some care has been taken to have water direct away. And if it's just a bit of water, it's an open rafter roof inside so the bit of water will only land on the vinyl floor and my sons toys. Think I'll give this a go....with one addition. As it is now the place is bug tight so I think I'll add a screen at the base to keep the biting bugs out.

Great input - thanKshatriyas all!
 
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Old 05-29-15, 07:45 AM
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I installed one years ago in NJ and I was going to put it over the house, but being able to look right through it gave me concerns. I ended up putting it over the attached garage where any water that came in would fall harmlessly on the concrete floor. I remained at that house for several years and never saw a drop of water on the floor. I still have my doubts so I prefer other solutions.

Now, keeping that space cooler when the sun is shining will be a challenge. Even with full soffit to ridge venting the best you could hope for would be half way between outside temps and boiling hot and experience tells me that will not be enough.

Is there any insulation anywhere inside this building?
How are the temps in the lower space?
What is stored in the lower space, ie fumes you would not want to invite upstairs?
Ridge or roof vents could be difficult looking at the low slope.

Bud
 
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Old 05-29-15, 08:23 AM
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There is no insulation in the building. All stick framed, sheathing then LP Smartside siding panels. OSB and standard shingle roof.

Temperatures here in Toronto run as high as 35 degrees in summer (95 F) to this last winter as low as -25 (-15F) in winter.

Down below is garden tools, patio furniture etc. all the gas powered stuff lives elsewhere for obvious reasons.

The roof is rafter on a center ridge beam along the ridge so the ridge vent would be a bit tough. Again the second floor is laid with sheet vinyl flooring so small amounts of water aren't a big deal. It's not like it would be coming into an insulated attic that's unatrended.

I'm thinking where there would be the most chance of water is during the spring thaw where a layer of snow over the vent melts off slowly and drips in over a still turbine.

I think I'd be less inclined to install this in the house roof but for this it may be a good idea.
 
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Old 05-29-15, 10:56 AM
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You will need to provide a source of cooler air so the vent has something to exhaust. If you treat the upstairs as all one attic, then a low vent gable could go at floor level. If the back side of that building is the shaded side, that is where I would be thinking of putting the intake.

High gable vents with floor level intake vents might provide some relief without the turbine.

Another approach which is difficult to discuss would be the use of radiant barriers. They have been so exaggerated that most discussions focus on what they won't do. But, if the bottom of your roof was covered with a foil material, the heat transfer to the inside would be significantly reduced. In the deep south they make and use a foil faced sheathing for their roof(s). You can buy a 1/2" or 1" foil faced rigid foam board and cut and fit it to the bottom of your sheathing. Just a thought.

One other idea would be to shade the roof to catch a lot of the solar energy before it hits those shingles. They actually make shingles with a high reflectivity to accomplish some of that.

Bud
 
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Old 05-29-15, 11:30 AM
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Thanks Bud. I hadn't really considered the intake but it does make sense to have one near the floor since the door is often closed. It's still a play house so beyond some clean fresh air I think we're good. Thanks again. Really good info
 
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Old 05-29-15, 12:00 PM
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The roof is rafter on a center ridge beam along the ridge so the ridge vent would be a bit tough.
You've never put on ridge vent, have you. That's pretty standard.
 
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Old 05-29-15, 07:04 PM
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True - I've never installed a ridge vent before. I saw one installed once and while it didn't look too difficult on a new roof, I really didn't want to tear up the shingle ridge that I built last year.

That being said, I picked up a turbine vent at the big orange store on the way home from work today. Took me no time to pop the hole out and install. I even got some screen between the hole and the base to keep the biters out.

This thing is great! It's a pretty still night but it hasn't stopped spinning. Don't know if it moves more air but it looks really cool.

The room became instantly cooler. I'll be keeping a close eye on it when it rains, but so far this made for an easy install and the air is definitely moving....If it proves to be water free I'd look at adding one of these to the roof of my house.
 
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