Need some schooling on Roof fans....

Messages
18,614
Location
Michigan
Hi all-

So my wife decided to have someone come out and take a look at our roof. (She was interested in metal singles, even though our roof is under ten years old) I knew we were not getting a new roof, but it was noticed that it was getting moist up there- it simply needs more ventilation up in the attic. He offered to put a few solar fans in to about the tune of 5k-kinda opened my eyes a bit!

Of course we didn’t jump at his offer, as I wanted to research much more to see we could do. I’ve looked online, and they have prices all over the place. This is something I would like to do-since I am allergic to mold! I know many of you have done stuff like this, and tend to be knowledgeable about it- so here I am looking for both advice and insight. Quick facts : 60 year old 1050sf ranch w/basement. Also, roof is black in color- cam with house(i know absorbes heat worse)

Thank you!
 

Strokenmerc

Site Donor 2021
Messages
209
Location
Va
If you do not have a vent-a-ridge and do have gables, a standard attic fan will work. Very economical compared to the 5k estimate.
 

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Messages
87
Location
GA
Many older homes have bathroom exhaust fans vented into the attic. Take a hot shower this time of year and the fan blows the moist air into a cold attic where the moisture condenses. The fan duct work could have come loose, or be poorly fitted.. Air leaks around light fixtures, electrical outlets and any other penetrations allow moist air to move into the attic. Get a good silicone caulk and seal up around penetrations in the sheetrock such as plumbing pipes or electrical boxes for switches, receptacles and light fixtures. Do you have sufficient venting for the attic? Owens-Corning has a calculator for determining thee net free area (the open space in the louvers) needed in the soffit vents and the ridge or gable end vents (https://www.owenscorning.com/en-us/roofing/components/vent-calculator). If you have the necessary roof vents you won't need a fan. However, if a fan is needed, one that uses a thermostat will only operate when it is hot. It won't ventilate a cold attic which is when the moisture is most likely to condense and cause problems. There are solar attic fans made to blow air out of a gable vent when the sun shines-no thermostat necessary and easy to do yourself.
 
Messages
3,159
Location
Chicago Area
I have to chime in with the 'add more vents' crowd.

Had to redo Mom's roof about 5 years ago and the guy who came out to do the estimate recommended against adding any sort of fan(s) and suggested adding more vents instead.
 
Messages
1,580
Location
UT
If you do not have a vent-a-ridge and do have gables, a standard attic fan will work. Very economical compared to the 5k estimate.

I had an attic vent fan installed in my attic several years ago. Cost me less than $300 installed. Thermostatically controlled, so it only comes on when the attic temperature reaches a preset limit. My furnace installer recommended it, claiming that it can lower air conditioning energy use. Since they only run when the thermostat turns them on, I don't know how much it would control moisture, though.

I believe the better solution to control moisture in the attic is more vents, as others have suggested. Installing several vents shouldn't cost anything near what you were quoted for the solar fans.

Whatever you do, don't waste money on the solar attic fans. They don't move enough air to make a difference.
 

daves87rs

Thread starter
Messages
18,614
Location
Michigan
Thank you for the responses! I was wondering about the venting myself. I do think I need more vents around the house..as I only have a few. Were would a good place to put more vents?
 
Messages
207
Location
WA
You can a fan that uses a humidistat instead of a thermostat, or both.

Vents are great and preferred, but sometimes they need a bit of help.
 
Messages
25,978
Location
Upstate NY
Soffit
Thank you for the responses! I was wondering about the venting myself. I do think I need more vents around the house..as I only have a few. Were would a good place to put more vents?

Soffit and ridge. But the flow from the soffit up to the ridge vent needs to be continuous. Attic insulation cannot block it? Baffles may be needed around the eves.
 
Messages
997
Location
MO
Do you have gable vents? If so, and they are open you don’t need a ridge vent. If you don’t have gable vents then a ridge vent is what you need l. A pic of your roof or house would help.
 

JC1

Messages
6,110
Location
Oshawa, Ontario Canada
I added a ridge vent to the highest part of my roof this year. Instead of 5 small vents every 4-5 feet apart i have a 2 inch gap on the top part of the roof for 30 feet of continuous length.

That change makes a big difference in removing heat in the summer months. Make sure you have as many vented soffits with baffles as well in as many bays as you can install in the attic. All of these items combined with allow the attic to breathe better and control moisture.
 
Messages
1,804
Location
San Antonio, TX
Man I had attic vents in my attic from the previous owner. I did an experiment. I have gable vents and a ridge vent but no soffit vents. Fans going I checked the temps every day at a certain time. Did this for a couple of days. Then I unplugged the fans and rechecked the temps in the attic daily. No discernible difference. The temp never got more than 16 degrees above amibent. I left the fans unplugged.
 

daves87rs

Thread starter
Messages
18,614
Location
Michigan
Do you have gable vents? If so, and they are open you don’t need a ridge vent. If you don’t have gable vents then a ridge vent is what you need l. A pic of your roof or house would help.

I have not taken pictures of my home recently...but I will try and add them here. With a broken tall ladder, the roof could take a little while.....
 
Messages
5,450
Location
Ohio
I wouldn't use a fan. I would have soffit vents cut in and a ridge vent installed. A qualified roofing specialist can calculate how much air intake in needed for the ridge vent and the area of your attic. Get rid of any box or other vents as well. You do not want them with soffit and ridge vents. You want cool intake air to enter low through the soffits, rise and exit out of the ridge vent. Anything else will disrupt the process.
 

daves87rs

Thread starter
Messages
18,614
Location
Michigan
I wouldn't use a fan. I would have soffit vents cut in and a ridge vent installed. A qualified roofing specialist can calculate how much air intake in needed for the ridge vent and the area of your attic. Get rid of any box or other vents as well. You do not want them with soffit and ridge vents. You want cool intake air to enter low through the soffits, rise and exit out of the ridge vent. Anything else will disrupt the process.

That makes good sense.....
 

daves87rs

Thread starter
Messages
18,614
Location
Michigan
These are the vents on each side of the house. They seem quite small to me. Working on a roof picture (need a new ladder)
 

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