Power Roof Venting. Necessary?
 

Coming from NJ. Purchasing new in Hillsborough section. While driving around the Villages during my last trip here I note that many homed have power vents installed in the roofs. Some had as many as four vents. Could someone inform me if they are worth installing. Do they really remove heat from the home? Are the worth the money?

Thank you in advance for answers to my question. Looking forward to living here. Closing on September 19.

Our independent home inspector strongly recommended we install one. We did. It was cost effective and has lowered the attic temp.

This question has been asked before, and is a contentious issue. People are passionate about this on both sides.

I have no personal gain here one way or another, but here is an interesting article on the subject. Note that most homes here in The Villages have met the manual J specs on ventilation with the ridge, below ridge and soffit vents. Many factors must be considered here, such as amount of existing ventilation, color of roof, etc.

Don't Let Your Attic Suck | The ASHI Reporter | Inspection News & Views from the American Society of Home Inspectors

Hope this helps,

Frank

I installed a fan in the garage to suck air from the garage and force it into the attic. This provides a two fold advantage, first it cools the garage, and second it forces to hot air out of the attic. To back this work you absolutely need adequate supply air to the garage. I did this by replacing the windows in the garage doors with screened vents. I think it works really well. As stated above you will find lots of comments. BTW the fan installation was around $100, the vents in the garage doors, about $120, and the approximate CFM of air being moved about 1000. Also, I use a thermostat to control the fan, only comes on when needed.
Hope this helps.

What you may be seeing are passive vents. For example, my house has 3 round vents on the roof but there isn't a fan in them.

Power ventilators have been researched by some of the energy labs. The bottom line is they may actually increase your electric bill by sucking air-conditioned air into the attic. Also, the physics of heat transfer in the attic is not what you might think. Heat is transferred by convection, conduction, and radiation. It turns out that radiative transfer from the hot roof sheathing is the primary mechanism for heat transfer in your attic. Unless you address that, nothing else will make much of a difference. Spray foam insulation on the underside of the roof sheathing is effective. A radiant barrier is another option. I have had power ventilators in a previous home (before I researched how ineffective they are) - they didn't help.

While driving around you probably noticed many have screens on the garage, some are motorized and some are horizontal sliders. If you're like us, and want to keep your garage door open, I highly recommend putting on the screen door. I've had one neighbor find a rattlesnake in his garage under his car, and we've had gators leave the executive course and take a stroll through the neighborhood. Plus if your laundry is inside the garage like ours, it gives the heat a way to escape.

After you have the screen installed, you'll probably also have attic steps installed inside your garage, a lot of free storage space up there. Crack the attic step opening about a foot. Standing directly below the steps you should feel a nice breeze coming into the garage up toward the steps. My electric bills on our CYV were running in the $105 range and since we started doing this, our bills have been in the $80's and $90's all summer long.

If you do a search on this site, you'll see this has all been discussed many times before and some have said the garage/home firewall will be breached if you keep the attic access open. I guess everything has a trade off, with a masonry CYV I'll willing to take the risk. Anyway, times when we're asleep the garage door is going to be closed anyway, and we have 3 smoke detectors inside our home.

This is our setup, and as you can see we went with the horizontal sliders on our 12' door. It's also half the price of the motorized units. However, mainly I went with this style was because I'm often outside in the yard, or washing the car, talking with neighbors, I found the sliders are great because you open just one little 3' section and slide it back behind when you exit. Those with the motorized one piece screens will open the screen and then not lower it back until they've gone back inside. So while they're outside the garage is unprotected.

https://imagizer.imageshack.us/v2/68...90/32/3ced.jpg

We are kind of going a bit off the original topic, as the original topic was Attic ventilation.
Venting the garage is a bit different, but of course another interesting subject.

Options include just opening the garage window a bit and cracking open the attic stairway to garage fans to screen doors.

There are basically four types of garage screen doors. There are pros and cons with all three.
A) Sliding screen doors, like John posted about.
B) Motorized Roll ups
C) Non-motorized one piece retractable screen doors
D) Motorized three panel retractable screen doors, using a piggybacked top rail system

Frank

One question I have asked before and never got an answer: Does a radiant barrier on the underside of the rafters have any effect on the life and/or warranty of the asphalt shingles.

My question is....By cracking open the garage attic steps, does this create any type of potential fire hazard.

Yes Yes Yes!!!!

We have a CYV and decided to install a solar attic fan to vent the hot air. I believe that it helps cool the house some and make the Air Conditioning bills a little lower.

One thing I did to my garage was to install Styrofoam panels on my garage doors. We have west facing garage doors and the sun blasts them all afternoon which heated up the garage. With the washer/dryer in there, it was uncomfortable to wash clothes or putter around in the garage. The panels noticeably reduced the heat in there. Bought the panels from Lowe's and it was an easy 2-3 hour DIY project. It also reduced the noise when the doors open and close.

Yes, but whoever installed the stair unit probably did not use fire rated material anyway. Most don't. The garage ceiling is a fire rated assembly.

This is great information for anyone looking to install a power attic fan. These homes are engineered for Florida weather and temps. What ever you decide to do , research it, things don't have to be done ASAP .

You should be able to find out who made your shingles. Call them and ask. A radiant barrier will probably raise the roof temperature. It is not clear what impact this will have on shingle life. You can try googling it.

Regarding the styrofoam panels for your garage door, did you get the 2" thick 4'x8' pieces or the 3/4" thick 4'x8' pieces? Any words of advice on installing them? Thanks.

I purchased the 3/4" 4'x8' panels. There is approx. a 1.5 inch gap that you can double up and fit the panels in. I used a razor knife, black marker and a 4' level and cut the panels to fit. I removed the horizontal hurricane reinforcement panels and fit the Styrofoam panels in and then reinstalled the hurricane panels. Snug fit and looks great.

Take your time, measure twice and cut once :icon_wink:

Good luck, total cost under $100.

This thread is going all over the place.

A few comments....

Insulating Garage doors- A few options.
1) Some folks have a "bubble wrap" type product installed. I am not a big fan of this method.

2) Some folks go to a big box store and buy the styrofoam or Thermax type panels, cut them and install them.

3) Ro-Mac sells the insulation kits made by Clo-pay, the company who makes your garage door. The R-value here is about 6.2 It does help insulate against the radiant heat and will keep your unconditioned garage cooler.

Cracking your attic pull down stairs-

Will it be a fire hazard? Well, strictly speaking, yes. Understand though that on the homes that have a gas furnace, there is already a air grate in the ceiling, so your ceiling no longer has a fire rating at that point anyway. And those attic stairs most always are only 1/4 inch plywood, which has almost no fire rating anyway.

Understand that garage ventilation and attic ventilation are entirely different subjects.

Thank you so much for the info and advice - this is exactly what I need to do.

Good discussion. I think no fan as the house was designed not to need one. I do have the reflective material on the roof plywood. I think a vent in the garage ceiling is a good idea and would reduce the garage temp a little. Have not done this but am tracking temperatures in the garage to see if it pays to add any insulation to the door and then will test the ceiling vent.

Has anyone with a real whole house attic fan not that solar version
notice any advantages ?

What is the payback time in electric costs if you pay $500.00 plus for these attic fans. Sales people them cannot give a specific reply. If you only reduce the attic temp by 10-15 degrees for the hottest part of the day, then much will one save on electric cost for that part of the day! How do you calculate that ? How many special fans are on the 50,000 plus homes in the villages? When look at the entire State of Florida, I wonder how may have special venting other than what the home is built with!

Who is paying $500? Installed they run half of that.

Lightning
 

Last week on an internet village news site they showed the firemen on top of a roof inspecting the spot where lightning had struck. In the picture right where they were you could see a metal roof top exhaust fan.
IMO living in the lightning capital I am not going to install metal objects on my roof

If you decide to use the insulation kit from Ro-Mac and you have a two car garage , you may have to have the springs in the door reset for that bit of extra weight. I got this information from Ro-Mac the other day. I think they quoted me a price for an 18 x7 door ,insulation kit installed and door adjusted for around $370.

Solar fan in roof.

Where? Who? How Much? I have never found one quote under $500!

Care to respond to my other questions or only the cost of fan. Please read entire post!

Styrofoam
 

I thought styrofoam was highly flammable?

Cool Breeze Garage and Lanai Screens
 

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Attic fire?? From what??

My mother has an AC roof vent and I have replaced the motor numerous times as they wear out fairly quickly, this would be the source of a fire if it binds up and overheats... Motor has to be ordered and then installed each time it goes.


Did you read this link in a previous post?

Don't Let Your Attic Suck | The ASHI Reporter | Inspection News & Views from the American Society of Home Inspectors

In other words, don't install that power attic ventilator. If you have some installed already, disable them so they never run.
Power attic ventilators can cause problems even without air conditioning. One potential problem would be sucking moist, moldy air up from the crawl space into the house. Another would be backdrafting a water heater and putting carbon monoxide in the house. These are real problems from real houses that have really happened.

If you're tempted to buy one because it's solar-powered and won't increase your electricity bill, go back and read what I just said. These things probably won't save you any money. Even if they're solar, they'll still suck the conditioned air out of your house and make your bill higher, not lower.

It will help the fire spread much quicker!! But it also helps cool garage and attic, if fan on.