Home Improvement Expert Danny Lipford

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Attic Venting for Metal Roof

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Metal roof.

Attic Venting and Installing Exhaust Fans

I have a new house with a metal roof and without a ridge vent. Please recommend a vent system without cutting holes in the metal roof.-Bjorn

Hi Bjorn,

That would depend on the style of roof you have. If your house has a gable roof, you can install a vent in each gable then mount an exhaust fan in the attic behind one of them that is controlled by a thermostat. If you have a hip roof, you would either have to replace the existing ridge with a vented one—making sure the roofing and sheathing at the peak are cut back so air from the attic can escape through it—or mount a power vent fan on the roof itself, which would require cutting a hole in the roofing.

If you decide on a roof mounted fan, position it high up on the back of your roof, but not so high that it is visible from the front. Solar powered models are available that don’t require wiring, though they are more expensive than hard wired ones. Be sure the soffit under the eaves is vented so outside air can enter the attic.



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36 Comments on “Attic Venting for Metal Roof”

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  1. Noe Saavedra Says:
    January 20th, 2008 at 12:23 pm

    What I can do toinstall exhaust similar to the pictur mi roof is like that. Thank for u help.

  2. Vince Says:
    May 16th, 2008 at 4:24 pm

    Hi,

    I would like to install a roof mounted, solar powered attic exhaust fan (although the incline is fairly steep and maybe I should hire a roofer) and was looking for a step-by-step procedure describing the removal of/and replacement of the asphalt shingles. I’m just a bit unsure of proper measurment, cutting and reinstallation of the shingles (ie. overlap, etc). Thanks!

    Vince

  3. Sarah Says:
    August 30th, 2008 at 6:29 am

    I have an older room in my home. I live in the trailer that is attached to the “bowling alley” ( this added room, which is fairly large; in which we have had to seal the fireplace (Rock); because the dampener is broken, put a plastic box over the top of the chimney and use black solid duct insulation to completely close off the fireplace.
    The windows in the “Bowling alley don’t open, are the “argon” double thickness.. this room is freezing in the winter & you could bake bread in it in the summer.
    The kitchen in the trailer is rather a Maze with an old built-in stove with oven over ( that the thermostat doesn’t work.) in back of this ancient stove there is this “Kitchen island” that is useless other than holding up the microwave.
    I Know this sounds like something I should just move out of; but with todays’ economy We Just can’t afford it.
    ( we are both disabled and don’t have the $$$ to spare to move, put down new deposits on the new house, Utility s etc.
    We could really use some help, Danny
    Thanks.. Sarah

  4. M. Yacovino Says:
    April 2nd, 2009 at 7:27 pm

    Can you effectively use both gable vents with ridge and soffet vents. I was told that you should not use all three. Any answer?

  5. David Says:
    April 22nd, 2009 at 8:36 am

    because the dryer vent goes up into the attic and travels over twenty feet, I am considering venting into the garage which is on the other side of the laundry room. Any siggestions on what to consider? Should I put the vent up a few feet to prevent rodents getting into the house?

  6. David Says:
    September 21st, 2009 at 9:59 am

    Danny,

    I want to install a air vent fan in my toolshed which measures about 17′ long x 9′ wide x 12′ high. It has a rollup door and two windows above on either side. Will your installation guidelines for installing one on a house apply to this kind of structure? Thanks.

  7. Official Comment:

    Ben Erickson Says:
    September 22nd, 2009 at 9:28 am

    Hi David,
    A standard house power vent fan should work fine to draw the hot air out of your shop.

  8. Werner Heigl Says:
    April 5th, 2010 at 11:38 am

    Hi Danny, due to the heat that builds up in summer (and the corresponding skyhigh electricity bills) I’d like to install a power mounted roof vent. I am fairly skilled and do not mind working on the roof. I was just up there and noticed that the roof has ridge vents. I’m wondering whether a powered roof vent would just suck the hot air back in that it blows out of the attic. The ridge vents are small in cross-section and the attic does get pretty hot in summer, so I think that even if the vent sucks air back there is still a benefit. Any advice on this issue?
    Thanks

  9. Frank Says:
    April 10th, 2010 at 6:33 am

    Currently I have ridge vents and soffet vents but in the warm weather my second floor gets unbelieveable hot. This is also were the thermostat is for the central ac system that I have.I’m thinking of installing a power roof ran to help get the hot air out of the attic and the second floor. What would you recommend I do??

  10. Official Comment:

    Ben Erickson Says:
    April 12th, 2010 at 10:12 am

    Hi Frank,
    While a power vent fan can help lower the temperature in your attic, it may actually work against the natural air flow generated by your soffit and ridge vents. Read our article on Combining an Attic Vent Fan with a Ridge Vent to find out more. Other options would include checking to see if you have enough insulation in your attic and installing separate heating and cooling systems and thermostats for each level of your home.
    Good luck with your project!

  11. Diane Says:
    April 12th, 2010 at 12:36 pm

    I am about to reroof my house and want to make sure the venting is correct. Right now, there is no ridge venting, but there is a powered fan in one gable. Do both gables need a fan or will one pull enough air from the eave vents? It is a pretty large attic with a steep roof. Thank you.

  12. Official Comment:

    Ben Erickson Says:
    April 13th, 2010 at 8:46 am

    Hi Diane,
    If you have soffit vents under your eaves, or some other way for air to enter your attic in addition to the two gable vents, you could put a gable vent fan in the gables at each end. If you don’t have another intake source for outside air other than the two gable vents, you should only have a fan in one gable vent (blowing out), since the other gable vent is used to draw air into the attic.
    Good luck with your project!

  13. Selina Says:
    April 15th, 2010 at 10:26 am

    We recently reshingled our roof, removed the attic fans and installed ridge vents. There are gable vents on each end of the house and soffit vents. Will this setup work the way it is supposed to? If not, what do we need to do? Thanks!

  14. Dave Says:
    June 3rd, 2010 at 8:03 am

    Hi Ben,
    I have a hip roof without any type of intake vents. There are two static, low profile vents on the roof and a single turbine vent. I was thinking of adding a fan to help remove the very hot air from the attic, but without any type of intake, would that work? Can a fan be added to or replace one of my existing vents?

  15. Official Comment:

    Ben Erickson Says:
    June 3rd, 2010 at 12:48 pm

    Hi Dave,
    You need to be sure you have way to take enough air into your attic before putting in a power vent. The intake should preferably be near the bottom of the attic, but doesn’t have to be. For example if you had a triangular gable vent on each end of your house, you could put a fan blowing out in front of one and use the other as the intake. Depending on where your vents are located, you could take out the one high up on your roof (turbine?) and use the others as intakes (if they provide enough intake area). Since they will be drawing air in, be sure rain will not be a problem.

  16. Debra Wilson Says:
    June 14th, 2010 at 2:09 pm

    recently installed a power vent (heat and humdity controlled). Our last 2 electric bills have tripled. Is this the vent? Are they that energy hungary? The settings are 105 degrees and 50 humidity.

  17. Official Comment:

    Ben Erickson Says:
    June 16th, 2010 at 12:28 pm

    Hi Debra,
    A typical attic power vent fan only draws about 2 amps of electricity, which equals 240 watts per hour (2 amps x 120 volts) or about a 1/4 kilowatt an hour (240 watts/hr ÷ 1000 kilowatts/hr). At an average price for power of $0.10 a kilowatt, your fan uses about 2.5 cents of electricity an hour ($0.10 x 1/4). If it ran around the clock, your attic vent fan would use about $18 of power a month (730 hours/month x 0.025). If it only ran during the day when it’s hot, it would use about half that much. Hope that helps!

  18. Debra Wilson Says:
    June 16th, 2010 at 9:27 pm

    Thanks this helps alot-I need to look into why my is costing so much–or if there is somethng else drawing all electicity

  19. Bruce C Says:
    July 28th, 2010 at 11:40 am

    Hi, looking to install a power gable vent in the attic , already have vents there but living here in hot and sunny Florida it gets really hot up there , have checked them out, but wondering what size electrical wire I should use to wire up the fan. 14/2 or 12/2? Thanks

  20. Official Comment:

    Ben Erickson Says:
    July 29th, 2010 at 9:48 am

    Hi Bruce,
    Most power vent fans draw around 2 amps, and 14 gauge wire is rated for 15, so it should be fine, but I would check the info or manual that comes with the fan as to wiring size and the number of amps the fan draws to be sure. Also, you should use grounded wire (14/3), and properly ground it at the fan and circuit breaker box. Good luck with your project!

  21. Mrs.Allen Says:
    August 14th, 2010 at 9:48 am

    My husband is thinking about installing a window ac unit,in our finished attic office, by cutting a hole in the wall, to the unfinished portion of the attic, to vent… Since the attic gets so hot, would the AC unit even be able to cool the room that its installed in? Also, would condinsation be an issue in the attic? He thinks he can put a catch basin beneath the AC unit and plumb that to the outside for drainage… Thoughts? My husband is handy, but this all sounds a little odd to me…

  22. Andi Parkinson Says:
    August 21st, 2010 at 12:21 pm

    Hi Bruce,
    My husband and I are trying to replace our 100 year old slate roof with gaf shingle. When getting quotes, we started to discuss venting. We have a Cape Cod with multiple roof lines and the attic portion is converted living space, except for the very top roofline, which is an approximately 4 foot space with gable vents on either end.
    The concern is there is no way to vent the roof through soffit vents or even smart vents, they won’t communicate to the roofline (if we put in a ridgevent for example). So, do conditioned air spaces, ie converted attic space, need to be vented? If they don’t need venting, then just the gables should suffice with a fan at one end, or just the gables with a ridge vent will work, correct?

    We really appreciate your advice, thank you

  23. Andi Parkinson Says:
    August 21st, 2010 at 12:23 pm

    added on to previous question:
    we have not had any issues with moisture build-up or ice damming (except for back to back blizzards this winter!), so does a slate roof naturally breathe and we will face these problems with no venting and a gaf roof? thanks!

  24. Ramon Says:
    December 24th, 2010 at 7:57 am

    Danny, I have a row house, mine is a middle unit, here in D.C.the roof has a power vent fan and not much of any kind of soffit(less then 9″). This winter is very windy and could feel cold air radiating from the walls. The rafter insulation is loose fiberglass and stops about a foot from going all the way out to the soffit edge. What should/how do I get proper air flow up there and still cut that air from seeping between the walls?

  25. Roger Vandiver Ph 706-833-9877 Says:
    March 19th, 2011 at 8:59 am

    I need to have my Attic Power Vent replaced. Do replace them? My house is about 18 years old and has 2000 sqft. w/double garage. I live in Athens Ga.

  26. Brett Says:
    April 4th, 2011 at 6:45 pm

    Danny,
    We have a 1914 home with a slate roof. The partially finished third floor gets so hot in the summer time that you cannot stay up there for more than 5 minutes at a time. Also, the attic space above the third floor is not insulated. We are considering having a powered roof vent installed as well as soffit vents and insulating the attic floor. Would insulating solve our problem alone or should we still have the powered ventilation fan installed?

  27. Official Comment:

    Ben Erickson Says:
    April 5th, 2011 at 9:48 am

    Hi Brett,
    If you don’t have any ventilation or insulation in your attic, I would start by tackling those two projects first, and see if that solves your problem. If not, you may need to add a power vent fan to the attic. Good luck with your project!

  28. Frank Says:
    May 13th, 2011 at 10:50 am

    Hi Danny,
    I’m looking to install a gable exhaust fan in my attic within the next few days (to beat the summer heat). Because the attic isn’t a frequently visited place in my home, I would like to purchase a top quality gable fan that is “maintenance free”(i.e. permanently lubricated motor) and will last many years. What is a top/highly recommended gable fan company(s) that you’d recommend?
    (Note: Doesn’t need to be limited to brands found only in the major home improvement stores) I’ve been told by numerous electricians that Lomanco makes a top product.

    Thank you.

  29. Leo Nicholson Says:
    August 8th, 2011 at 8:27 am

    We have a home in Hattiesburg, Mississippi. It is a 1 1/2 story with sprayed in cellulose insulated walls and 14″ blown in cellulose ceiling. The downstairs is 2100 sqft and the upstairs is 1300 sqft. The roof has a 10/12 pitch. It has Georgia Pacific Radiant Barrier Sheeting and vinyl air channels between the rafters from soffit and 2 large porches to attic. (90 7×10.5” channels). The porch ceilings and soffit are 100% perforated vinyl.

    I’ve just discovered that the builder failed to cut the sheeting for the installed continuous ridge vents. There is no ventilation at present. I need to find out what I should do to correct this and found your web page. My attic temperatures are not excessive, but could be improved. It appears the radiant barrier works well. Also, I am concerned about mold/mildew possibly forming due to possible excessive moisture. It is dry at present and has no problems.

    I recorded these temperatures yesterday with a remote thermometer:

    Outside Attic Var

    07:00:00 AM 78.6 75.2 -3.4 Overcast
    08:12:00 AM 80.2 76.1 -4.1 Overcast
    09:12:00 AM 82.2 75.9 -6.3 Overcast
    10:18:00 AM 84.0 82.6 -1.4 Overcast
    11:21:00 AM 85.1 87.3 2.2 Overcast
    01:30:00 PM 88.2 96.1 7.9 Sunny
    02:36:00 PM 90.1 102.9 12.8 Sunny
    03:37:00 PM 90.5 105.6 15.1 Sunny
    04:32:00 PM 91.2 106.3 15.1 Sunny
    05:35:00 PM 90.5 106.2 15.7 Sunny
    06:30:00 PM 89.2 101.8 12.6 Sunny
    07:30:00 PM 87.8 94.1 6.3 Sundown
    08:20:00 PM 86.0 86.9 .9

    Should I use power gable exhaust fan or roof mounted power exhaust fan? I assume I do not need intake vent in the attic due to adequate soffit vents.

  30. Leo Nicholson Says:
    August 8th, 2011 at 9:06 am

    Should have been: 90 7×1.5” channels:

  31. Doug Hess Says:
    September 6th, 2011 at 11:11 am

    Danny,
    We are researching proper venting for a 100+ year old church. The church has only gable vents (approx. 24 sq.ft total)and a history of pealing paint on interior walls. The approx. 60′x80′ attic with an 11/12 roof pitch looks like it needs around 4500 CFM of fan venting. The existing heavy duty well built 48″ belt driven fan (30 years old) is not operational (missing fan blade) but looks to have been too large depending on the blade pitch. With the motor rpm and pulley ratio, it rotated at about 160 RPM. Do you suggest we look for a replacement blade or replace entire fan assembly for 4500 CFM venting if this is the correct amount. At this time we don’t know how well sealed the air conditioned and heated sanctuary is from the attic but there is some attic insulation. Since we are limited to the structural changes that can be made due to historical preservation we are looking at our options to reduce attic heat and moisture. Any suggestions you have would be welcomed or if you can suggest any local contractor with this expertise in the Charleston, SC area we would appreciate it.
    Thanks You for any help you can provide.

  32. Ulysses Freeney Says:
    February 12th, 2012 at 5:59 am

    Hello My name is ulysses and I have a question Or two, about a Baptistry We have,We notice that , after We put installed,a heater in the baptistry,that a lot of moisture build up was evident, an mold began to grow on the walls Question is can We do to Be rid of this, situation,I believe that a exhaust fan is needed ,or maybe some type of ventilation, system, can you help.

  33. Geard Romano Says:
    May 3rd, 2012 at 10:12 am

    When calculating the NFA of a soffit or fixed screened gable vent shouldent I reduce the actual size by 50%?

  34. Joe Says:
    June 27th, 2012 at 10:24 am

    Hello,
    My home was built in 1984 and is 1320 sf. I only have gable vents, and a small 8 foot section of ridge vent. No vented soffits. What should I do? I am thinking of just adding a attic fan at one gable end?

    Thank you for your help.

  35. elaine Says:
    July 17th, 2012 at 7:25 am

    Help! I have a split level house. A new roof was put on about 6 years ago with an attic fan, that is vented. I just found out that the roofer never installed any venting( a ridge vent was on his proposal). There are no soffit or gable vents. I got some leaks and called for estimates and then found out about the venting. The roofers giving those estimates disagree on what venting I should now install. One wants to install 4 louvre type vents and the other just a ridge vent on the lower peak of the split. What should I do?

  36. Michel (Mike) J. Gauthier Says:
    July 21st, 2012 at 2:09 pm

    Can you install an exhaust fan part way down a roof slope? I have two rooms that are not service by the current exhaust fans, and are always very hot in summer. Air conditioners are running all the time.

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