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On your roof jobs do you recommend roof vents and / or exhaust fan. Which is better - I would like to use both. 
Re: Roof vents and/or exhaust fan.
With a new roof job on a house do you recommend roof vents and a new exhaust fan to replace the one that is there? I don't want to give up the fan but one contractor recommended this. One estimate included a new fan. Another listed roof vents as an optional cost and will remove the existing fan. There are side vents. I am confused as to which way to go. I would like to have both - what do you think of a solar fan.Show me another question! | Report Abuse
Asked by SusieGrace from Charleston, SCAnswered 16 years ago.
58 Answers
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There are many ways to ventilate your attic space but if done incorrectly or in excess will defeat the purpose all together. The principle of roof ventilation is simple, hot air rises and exits through the roof ventilation whatever that may be and draws excess moisture with it. The roof ventilation is simply half the battle, when hot air escapes through the vents it needs to be replaced, this is accomplished with under eave vents, or vents located in the soffit at the gutter lines. If those are not present then the air is more than likely replaced with air from within the residence. With this setup there is a vacuum that is created as the hot air escapes through the vents on the roof, new air is pulled into the attic through the soffit vents and allows the roof system to breathe. It also pulls the moisture out of the attic that may not rise with the heated air. No two different types of roof exhaust vents should be used together on any given roof. Instead of air being drawn from the soffit where it is supposed to, it will be drawn from one or the other different roof vents. For instance, you have a power ventilator that is running but also have box vents in the roof. The air is then drawn in from the box vents as opposed to the soffit and the only portion of the attic that is getting vented is the portion between where the box vents lie and the power vent sit. This eliminates the entire attic ventilation that was the goal. There are up sides and down sides to each ventilation system available to homeowners and below I will list them.
Powered roof ventilation (Solar or 120V): Although they move a lot of air and the more modern units have a hemostat which ventilates moisture in the winter when the heat is not high enough to activate the fan, they are still mechanical units and prone to mechanical failure. The motors tend to burn out prematurely. They have steel bearings that tend to rust (due to moist air) causing them to seize or the very least create a squealing sound when it runs. Most 120V units need to be disconnected by an electrician (existing unit) and re-connected by the same. We used to do this but in the liable world we live in there is too much risk to the contractor. Also, these are usually not as successful in distributing ventilation over the entire attic.
Box Vents (static vents): Great units and are not mechanical, so mechanical failure is not an option. They are economical and vent very well when used with good soffit ventilation and work very well in an open attic situation. They do need to be placed very close to the ridge of the roof. Ridge Vent: This is the best ventilation you can buy. It has several advantages the others do not. It works very well with good soffit ventilation in creating a vacuum or air flow in an attic. It is also non mechanical so it cannot break down. Its sits at the very peak of the roof so all of the attic, from the soffit to the ridge is in the flow of air. It is the only ventilation to be used in a vaulted ceiling situation where the interior ceiling is attached to the main rafter that the roof sheeting is attached to, creating flues between each rafter. During a breezy day as the wind sweeps over the ridge it also creates suction, almost like the wing of an airplane. One other advantage to ridge vent is not very visible and therefore appealing to those whom don’t want a lot of box vents on the back of their home. There are a couple disadvantages to it though; it will not work well on a hipped roof with very small ridges at the top. Also, if it is not installed properly (i.e roof deck is cut back from ridge rafter 1.5” on either side) it will not function properly. Whirly Birds: Once again these move quite a bit of air but are also mechanical based units and are prone to eventually seizing. If they stop rotating then they are not ventilating and water entry is possible. They are also the most visible roof vent you can use. Gable Vents: “Side Vents” have been deemed to not function effectively as roof ventilation. As a matter of fact with a good ventilation setup the gable vents should be covered from within the attic with poly to eliminate any air entry from this high point in the attic. It once again falls into the problem I described above, only ventilating the space between the gable vent and what ever roof ventilation you may be using. We would recommend picking one system and sticking with it. I would also have my soffits looked at and evaluated to make sure they are present and in good working order. Otherwise roof ventilation is a mute point and may actually create energy inefficiency by pulling replacement air from within the home. For more information visit Lomanco’s site below, they are the leader in ventilation products for your attic. http://www.lomanco.com/ventilation.html Most qualified professional roofing contractors are knowledgeable about effective ventilation, and roof replacement time is usually the best time to consider upgrades. If you have any further questions please feel free to ask.
Answered by Commonwealth Roofing Corporation
1449 Hugh Ave,
Louisville,
KY, 40213,
502-459-2216
(Novice with 7 pts.)
Answered 16 years ago. -
Moving air in an attic is a good thing since the temps in there, depending on where you live can get up 150 degrees or more. Having a ridge vent gets rid of all the hot air trapped at the top of your attic and the eve vents help to move it along. An attic fan is just a better way to cool down the attic and move the air. Solar is good since you don't have any wiring to do. Just don't buy the cheapest one out there and make sure the solar panels are facing south.
Answered by Blue Ridge Roof Cleaning of Virginia
220 Rosser Ave #7,
Waynesboro,
VA, 22980,
540-949-6277
(Novice with 159 pts.)
Answered 15 years ago. -
Roof Ridge Vents are specified by the Mfg in their warranties.
Power vents work fine as long as their are working, motors fail from time to time.
Two systems on your roof could work against each other, if they are not installed correctly.
General Rule: use Ridge Vents, make sure they are installed by a Certified Installer connected to a manufacturer of the Shingles you are going to use.
Answered by Advanced Commercial Roofing, Corporation
2600 Louisville Rd, savannah, GA 31415,
Hardeeville,
SC, 29927,
843-295-5245
(Novice with 4 pts.)
Answered 16 years ago. -
if you have the exhaust fan and roof vents they will work against each other. the exhaust fan will suck right from the roof vents. For instance in a test done the attic was filled with smoke and the exhaust fan was sucking right from the roof vents and not removing the smoke. A exhust fan will remove the heat faster but only in the designated area. A continuous roof ridgevent will remove the heat and moisture evenly and more effectivley.
Answered by Ideal Roofing & Construction
310 Tompkins St,
fond du lac,
WI, 54935,
920-251-2725
(Novice with 3 pts.)
Answered 16 years ago. -
Shingle-vent combined with soffit vents at a 2 to 1 ratio is recommended by the top manufacturer CertainTeed Corp. If you don't have soffit vents you can use the edge-vent system made by air-vent. I would replace the fan with one including a humistat. This will act as a back up in the summer on hot days,and will remove moisture the rest of the time. I wasted my money on solar fans. They don't move air as I had expected.You can light a match next to them.
Answered by Marty's Custom Roofing
117 Shady Creek Ln,
Fredericksburg,
VA, 22406,
540-286-3017
(Novice with 18 pts.)
Answered 16 years ago. -
Attic ventilation ultimately comes down to personal choice. Some people like turbines, some like louvered static vents and some prefer electric or solar vents. These will always eventually break down and you will be left with a static vent anyway, so I suggest going static to begin with. My company always prefers to go with ridge ventilation. It looks very sleek and works with convection to vent hot air out the very top of your roofing system. Providing more actual area of ventilation than static or power vents I feel its the best system. Hope this helps!
~Kelley McBride - Owner - McBride Roofing_thumb.jpeg)
Answered by McBride Roofing & Repair
4616 E. Cesar Chavez,
Austin,
TX, 78702,
512-363-6092
(Novice with 1 pts.)
Answered 16 years ago. -
It's hard to answer the exhaust fan question without seeing it first hand, however if it is in good working and good physical condition I don't see the point of replacing it. As far as the roof vents these are very important for ventilation in your attic/crawl space areas. It would not hurt at all to have the side vents and the roof vents. If you are having a new roof installed I would for sure have the new roof vents installed. A solar fan would work good if you have the proper sunlight for it, if you go this way I would have the fan installed on the side of the roof that gets the most sun(afternoon sun).
Answered by AZ Roof Restoration LLC
11053 N. Flycatcher Dr,
Marana,
AZ, 85653,
520-403-6565
(Novice with 29 pts.)
Answered 16 years ago. -
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Answered by Loan Des Plaines, IL, 60019, 312-768-5569 (Guru with 1856 pts.)
Answered 10 years ago. -
You can use both power vents and ridge vents. I recommend the ridge vents to all my customers as they allow more air flow through the attic. Even if the power is off your attic will still continue to cool. The price on the ridge vent is more affordable than the powered vents.
Answered by Pasadena Builders Surplus Outlet
2125 Richey St.,
Pasadena,
TX, 77502,
281-815-2109
(Novice with 4 pts.)
Answered 14 years ago. -
You can use both power vents and ridge vents. I recommend the ridge vents to all my customers as they allow more air flow through the attic. Even if the power is off your attic will still continue to cool. The price on the ridge vent is more affordable than the powered vents.
Answered by Pasadena Builders Surplus Outlet
2125 Richey St.,
Pasadena,
TX, 77502,
281-815-2109
(Novice with 4 pts.)
Answered 14 years ago.
