Adding Soffit Vents
Attics and Basements, Interior, Repairs and Installation by Ben Erickson
Keeping your attic cooler in the summer can increase the life of the roof as well as saving money on your air conditioning bill. To effectively cool the attic, outside air needs to circulate through it. One solution is to bring fresh air into the attic through soffit vents under the eaves.
The general rule of thumb on the amount of total attic vent space needed is to have at least one square foot of vent space for every 150 square feet of attic area. Ideally, half the vents should be located in the soffit at the bottom of the roof and half in gable or ridge vents near the top to allow for natural circulation of air through the attic.
To find out how many soffit vents you need to install:
- Calculate the total vent area needed: Multiply the length of the attic times the width in feet to find the attic area, then divide by 150 to find the total square feet of vent space needed. [(length x width of attic in feet) ÷ 150 = total sq. ft. vent area]
Example: a 50′ x 30′ attic would have a total area of 1,500 sq. ft., divided by 150 equals 10 sq. ft. of total vent space needed. - Calculate the soffit vent area needed: Divide the total vent area by two to determine the soffit vent area. [Vent space ÷ 2 = sq. ft. soffit vent area]
Example: 10 sq. ft. vent area ÷ 2 = 5 sq. ft. soffit vent area. - Calculate the area of each vent: When known, use the “net free area” supplied by the manufacturer of the venting you will be using, which takes into account the actual open area of the vent rather than the total vent size. For square or rectangular vents, muliply the length times width of the vent space in inches, then divide by 144 to convert into sq. ft. [(l x w in inches) ÷ 144 = area of vent in sq. ft.]
Example: a 6″ x 12″ vent would equal 72 sq. in., divided by 144 equals an area of 0.5 sq. ft. per vent.
For round vents, multiply the radius of the vent (half the diameter) times itself (squared), then multiply the total by 3.14 (pi) and divide by 144 to find the number of square feet [(r² in inches x 3.14) ÷ 144 = sq. ft. area per vent].
Example: a 6″ diameter vent would have a radius of 3″, multiplied times itself would equal 9″, times pi (3.14) would give 28.26 sq. in., divided by 144 equals an area of 0.196 sq. ft. per vent. - Determine the number of soffit vents needed: Divide the total soffit vent area by the area of each vent. [soffit vent area in sq. ft. ÷ individual vent area in sq. ft. = number of vents needed].
Example: 5 sq. ft. soffit vent area divided by 0.5 sq. ft. vent area equals 10 soffit vents needed.
Space the soffit vents evenly around the bottom of the low sides of your roof.
There are several different types of soffit vents available including continuous, circular, and perforated vents made for vinyl siding. We’ll discuss the easiest to install, standard 8″ x 16″ vents.
- First mark off the space where you want the soffit vents to go, spacing them so they fit between joists or rafters.
- Cut the hole slightly smaller than the vent itself with a circular saw or a saber saw. Don’t forget to wear eye protection.
- Check to be sure that the hole vents into the attic and isn’t blocked by insulation or other obstructions.
- Screw or nail the vent into place.
The fresh air the soffit vents draw in should be expelled near the peak of the attic through vents in the gables, ridge vents in the roof, wind turbines, or power vent fans.
65 Comments on “Adding Soffit Vents”
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August 30th, 2007 at 11:59 am
Can a 8″x 16″ be install between each rafter and both side of roof.
Ben Erickson Says:August 30th, 2007 at 3:09 pm
Milt,
The rule of thumb on the amount of vent space needed is approximately 1 sq. ft. of vent space for every 150 sq. ft. of attic area. So if your attic is 1,500 sq. ft., you divide that by 150 to get 10 sq. ft. of vent area. Ideally, half the vents should be located in the soffit at the bottom of the roof and half in gable or ridge vents near the top. Divide the vent area by the opening in each vent to come up with the number of vents needed. For example a vent with a 6”x12” opening would equal 0.5 sq. ft. Space soffit vents evenly around the bottom of the low sides of your roof.
November 8th, 2007 at 1:19 pm
I am ready to do this plus add styrofoam ventilation channels. I am wondering if the ventilation channels go only where the soffit vents are or must I do all the roof rafters with the channel vents?
December 26th, 2007 at 10:14 pm
My house is 22×60 the attic is about 4ft from attic floor to the peak not a walk up attic i want to install 4in soffit round holes how many do i need. thanks
Ben Erickson Says:December 27th, 2007 at 4:52 pm
Bob,
Using the formula above, you would need 8.8 square feet (or 1,267 square inches) of vent space in your attic. Since each 4” diameter hole would have an area of 12.56 square inches (3.14 x r²), you would divide 1,267 by 12.56 to come up with 101 vents. That’s a lot of holes to cut! If half the vent space is near the top of the roof in ridge or gable vents, that would reduce the number of soffit vents at the bottom to 50.
February 10th, 2008 at 7:03 pm
Does it matter whether the vent holes face
away from the house into the wind or should they face away from the wind toward the side
of the house so they dont clog?
February 13th, 2008 at 8:27 pm
I have a 28 X 24 garage with 24″ centers of rafters.
I went with a plywood eave. The ceiling is insulated, and it is cold up here, 25 degrees f for a few months of the year.
I was going to put an 8″ x 16″ soffit vent on every second rafter in the front, starting with the outer most ’space’, between rafter 1 and 2. On the rear I was going every second one, but alternate by starting between rafter 2 and 3.
I thought that would give better ventilation that mirroring front to back.
Also, do I need them in the ends of the garage, where the peak is?
Thanks.
February 21st, 2008 at 10:42 am
Just a quick comment in regards to Ben Erikson’s response to Bob dated December 27, 2007. Apparently, Mr. Erikson did not double-check his math. According to the formula, Bob’s attic area would be 1320 sq ft not 1267 sq ft. Dividing 1320 by 150 gives a vent area of approximately 9 sq ft which would interpert into 9 4″ soffit vents or 10 if you like even numbers.
Nicholas Roussos Says:February 21st, 2008 at 6:21 pm
Chris, I think you’re confusing sq feet and sq inches. They’re not the same thing. For instance you say he needs a vent area of 9 sq ft and that 9 four inch soffit vents would do. But 9 four inch holes does not equal 9 square feet.
February 22nd, 2008 at 9:21 am
My mistake and thanks for the clarification.
February 29th, 2008 at 2:33 am
My garage floor shows a crack in it. It appears to come from the outside wall about half way in the garage. Also, lots of water comes off the trucks wheels from melted snow or just rain water. What is the best thing to do in this case?
April 6th, 2008 at 8:52 am
We live in a 50’s style ranch and over the years the soffit vents have been painted over while painting the overhang. We would like to replace or restore these, but haven’t been able to find the size we need to replace them. Any ideas would be appreciated.
April 15th, 2008 at 11:15 pm
Rick,
It doesn’t have to be exact. Just get one that is larger then your existing as they just nail or screw over the cut out opening.
May 19th, 2008 at 10:57 am
Ben,
I used your formula to do my house (38×60), and had planned on using soffit vents with three 2″ round holes on them-until I realized that I would need a crazy amount of holes. So here’s my question-if i modify the hole to make it bigger, is there any such thing as too much ventilation when it comes to attics?
Ben Erickson Says:May 19th, 2008 at 12:02 pm
Paul,
While you can have too little venting in your attic, you can’t really have too much. Keep in mind that it’s best if half the venting is in the soffit at the bottom of the roof and the other half at the top in gable or ridge vents to allow outside air to flow through the attic. Depending on local building codes, the venting may be reduced to 1 sq. ft. of vents for every 300 sq. ft. of attic area if the house has an adequate vapor barrier and the venting is balanced between the top and bottom of the attic.
May 20th, 2008 at 10:17 am
I remember hearing or reading somewhere that soffit vents should not be installed directly above windows (and doors also?), though the picture here shows one squarely above a window
I’m adding soffit vents to my home, and the ones I’ve got are currently evenly placed, except for above windows. Any truth behind this?
Thanks!
Ben Erickson Says:May 22nd, 2008 at 1:14 pm
Hi Adam,
I see no problem with locating a soffit vent above a window or door. Many houses have continuous soffit vents which go all the way across the house. The only reason I could think of not to put a vent over a window would be in the unlikely instance that a downdraft caused hot air to come out of the vent and in an open window. However, since hot air rises, under most circumstances the soffit vent would be drawing cool air in rather than letting hot air out.
June 9th, 2008 at 1:40 pm
Danny:
I have a run the numbers on my vents and I am a little short on the total vent opening space, I think. I have about 3,400′ of floor space in the attic and 26 soffit vents that are about 8″ X 16″ and maybe 60% open (the efficiency is eaten up by loovers and screens. Then on the roof I have six wind turbins that are about 12″ (when i measure the inside diameter they seem like they don’t quite measure 12″ but are more than 10″. If I did the numbers right I have enough soffit vent but need a little more venting higher up. I live in Texas and when the outside temp is 100F the attic temp is arond 135F. I had read once that if the attic were properly ventilated the attic temp should be around 105 if the outside temp is 95. What are your comments on this? Do I need more vent space and if so, where? Is it really reasonable to expect to get the attic temp down to 105 with an outside temp of 95 with natural ventilation?
July 13th, 2008 at 11:52 am
Would it be a problem to install soffit vents near or over an A/C? Also, when I install my bath vent out through the soffits, will that interfere with the attic soffit vents? Should I vent thebath out the roof? I have a roof with a ridge vent and gable vents, but no soffit vents. I can install some easily on one side, but the other side has the problems outlined above. This side also has half the soffit length because of an addition with a torch-down roof. Maybe I can get some venting through the torch-down roof soffit by cutting a hole in the roof to allow the air to flow.
Thanks for your help
Ben Erickson Says:July 14th, 2008 at 10:28 am
Gary,
Since AC units expel quite a bit of heat, putting a soffit vent directly above one wouldn’t be the best place for it. Rather than taking up one of your existing soffit vents with a bath vent, perhaps you could cut a separate hole in the soffit for it, or run it out the gable if it’s not too far away.
August 3rd, 2008 at 3:20 pm
where can i purchase that vent cover? i have 3 2″ holes inline every 2 feet all around the house – most of the screens are missing & need to cover them. thank you.
August 5th, 2008 at 2:19 pm
When installing soffit vents, do you install them with the vents facing the house or with the vents facing away from the house?
August 18th, 2008 at 8:16 pm
fyi regarding direction of vents
September 14th, 2008 at 7:22 am
ATTIC VENTILATION FOR HOMES
B. R. Stewart
Agricultural engineer-environmental control ~ Agricultural Extension Service ~ Texas A&M University
http://www.factsfacts.com/MyHomeRepair/ventilation.htm
September 19th, 2008 at 2:19 pm
per http://www.diynetwork.com/diy/he_home_insulation/article/0,,diy_13895_2275822,00.html
vents point toward the house
October 14th, 2008 at 1:23 pm
I have a house where the second floor is a loft. There are triangular crawlspaces to the sides of the room and a triangular attic space above the ceiling. There is an access door to the northern crawlspace and no access to the attic space.
The crawlspaces to the sides are not connected to the attic, but there are soffit vents and ridge vents. Since the crawlspace is not connected to the attic there can be no airflow from the soffit vents to the ridge vents.
The problem is that in the winter we often get strong, cold north winds. This sends lots of cold air into the crawlspace via the soffit vents, and then directly into the house via the crawlspace access door and most of the electrical outlets on that side of the house. Sometimes large areas of the loft will be 25 degrees colder than the first floor, and frequently the plumbing in the loft bathroom freezes (the cold air seems to run under the tile floor (burr!) and chills the sink plumbing. Have to put hot water in the tub and wait for it all to thaw out).
So, what’s the correct way to do this? Should the crawlspace have gable vents? This would allow air to flow up the soffit vents and then out the ends through the gable vents. I’d still want to seal the leaks into the living spaces, but hopefully the added vents would reduce the air pressure in the crawlspace so air wouldn’t be forced into the house.
October 16th, 2008 at 3:42 pm
Can there be too much soffit open area ventilation
We are redoing our soffits and cutting out the hard board above the soffits. Is this ok?
January 24th, 2009 at 2:42 pm
Is there an answer to B. hanson 11/8/07 re: how many baffle vents per soffit?
Your calc’s for # of required soffits is very helpful. Wondering if baffles are needed between all rafters or only those rafters over soffits.
Install soffits on ends and in middle for best results? Ie: need or 3 for 13 rafters.
Thank you.
Ben Erickson Says:January 26th, 2009 at 9:38 am
Kevin,
Baffles are only needed in the rafter/joist spaces where soffit vents are located. If you have continuous soffit vents, install baffles in enough (or all) the spaces to give you the needed square footage of vent area. Space the soffit vents out so they divide the attic area into equal areas. In your case, I would put one in the center, then come in a couple of rafters on each end for the other two.
January 31st, 2009 at 3:17 pm
This home was built around 1929 near Schenectady, NY. Uninsulated & no soffit vents. The roof rafters are 24″ on center 5.5″ deep. i want to finish the attic space, but insulate rafters and vent soffits in the same project. Do I need to channel soffit venting to the ridge venting(pre-existing)before insulating or not even channel the venting? Should I install vapor barrier before finishing attic ceilng? Is styrofoam insulation available in higher r-rating density than fiberglass? Thanks for any advice on my first major upgrade!
dan s
March 16th, 2009 at 6:49 am
Dan,
You calculate, for lack of a better word, gross area of needed vents. But manufacturers report Net Free Area on their vents (the actual amount of air space in the vent, not it’s overall dimension). My problem – I have ridge vents rated in Net Free Area per lineal foot; how do I equate that to a gross vent area as used in your example above, so I can see if my total ridge vent area is adequate? Thanks.
Ben Erickson Says:March 16th, 2009 at 7:14 am
Hi Sam,
The ratio of vent area to square feet of attic space is more of a general rule of thumb than written in stone, as there are a number of other factors that are hard to quantify but are important (such as your climate, how effective the draft or fan in your attic is in moving air through it, etc.). If you know the net free area of your vents, feel free to use it rather than gross vent area in making your calculations. It’s hard to have too much venting in an attic, so having a bit more than reccommended shouldn’t be a problem.
April 8th, 2009 at 4:07 pm
I have a 2500 sq-ft attic floor, ten 8″ x 16″ soffit vents, 2 wind turbines and radiant barrier roof decking. 7 of the soffit vents are on the north side of the house, only 3 are on the south (hotter) side and there are none on the west (front) and east (backyard) sides. How do these impact the rule-of-thumb of 1 sq-ft vent area per 150 sq-ft of attic floor? Following the formula, it seems like I need at least 6 more soffit vents. Thank you!
Ben Erickson Says:April 9th, 2009 at 7:30 am
Hi Bing,
While it wouldn’t hurt to add more soffit vents on the east and west sides of your house to give a more even flow of air through the attic, you already have about half the amount of venting needed in soffit vents, so where you should really put your efforts is in more venting near the peak of your attic roof with either more turbines, gable vents, or a vented ridge.
April 9th, 2009 at 12:20 pm
I have an attic area of 1176sq.ft. Based on the formula I need 7.84sq.ft. of total vent area. My current ventilation is 2.17sq.ft. from gables and 6.66sq.ft. from ridge vent. Do I need to add soffitt vents? If so, how many sq,ft.?
April 13th, 2009 at 12:26 am
I LIVE IN SOUTH TX;RGV.MY HOUSE WAS BUILT IN 1929 WITH FLAT A ROOF AND NO CRAWL SPACE.I AM INSTALLING NEW WINDOWS AND SIDING.THE SOFFATS ALL AROUND MY HOUSE ARE 4 FT.DO I NEED TO HAVE VENT IN THE SOFFATS TO PREVENT MOLD AND MOISTURE .
April 27th, 2009 at 11:20 am
My colonial (built in 1930’s) has NO soffit vents and only a continuous ridge vent 50′ in length. The attic has two finished rooms on both sides of a center-hall staircase. The front of the house faces directly South and both rooms get extremely hot in the summer. Since I am not sure if there are baffles located between the roof and the interior walls and dont know how far each joist is located from one another, how do I pick the proper location to install my soffit vents? The way I see it, I have 1000sq ft of attic space so need (~7sq ft of total vent area/2) 3.5sq ft of Soffit vent space. Id like to use 6×12″ soffits… Any advice?
April 27th, 2009 at 11:21 am
sorry..forgot one part..should I locate all soffit vents on the south facing side (disregarding the North face) or should I do both equally?
Ben Erickson Says:April 28th, 2009 at 7:45 am
Hi Sandy,
I would put the soffit vents on both sides of the house for even air flow. You should be able to determine the joist spacing and location by looking in the attic. If not, try looking on the soffit for the location of nails to see where the joists are, or using a stud finder to locate them. You could also drill a small pilot hole, and insert a bent coat hanger through it to feel in each direction for the joists.
Hope this helps.
April 28th, 2009 at 10:21 am
Ben, I really appreciate it. Should I be concerned that I dont have Baffles?
Ben Erickson Says:April 28th, 2009 at 10:30 am
Sandy,
Baffles are usually installed before insulation is blown in to prevent it from clogging up the vents. Since insulation doesn’t move around once it’s in place, if you can see or feel a clear path for the air to vent up between the joists/rafters, it should be fine.
May 9th, 2009 at 7:47 pm
When figuring out soffit vent requirements for an attic–and calculating total vent area needed–does height of the attic come into play?
May 21st, 2009 at 4:54 pm
Hi Ben,
I have an older ranch style home which I recently had re-roofed and a ridgevent installed.I would like to install soffit venting to take full advantage of the ridge vent.My soffits are aluminum covered with the wood soffit under that.I drilled a small pilot hole (2″)and find that there is a space of about an inch or so between the aluminum and wood soffits.Must I be sure to get deep vents that push through both the aluminium and wood soffit and into the attic?Or is it ok to just cut through both the aluminum and wood and only place a surface vent over the aluminum?Thank you for your help.
Ben Erickson Says:May 22nd, 2009 at 8:59 am
Hi Derek,
As long as you cut through both the aluminum and wood so that there is a clear path for air to flow through to the attic, a surface mounted vent attched to the aluminum should be fine. If you’re concerned about it, or would like a more secure attachment for your vent cover, cut and fit wooden strips around the opening between the aluminum and wood, then screw the vent through both the aluminum and wood strips and into the wooden soffit board.
May 22nd, 2009 at 11:27 pm
I have 1000 square feet of attic space and have 50 soffit vents. 20 in front, 20 in back and 10 on the attached garage. Seems like plenty but the roofer that’s quoting my job said it’s not because they are the perforated type and don’t allow much air to enter. Other roofers said it’s plenty because the soffits aren’t air tight and draw air through the holes and surrounding gaps.
Any idea if the perforated type soffit vents are ok to use and if I have enough vents?
May 28th, 2009 at 12:34 pm
One of my attics has both a turbine and power fan, and seems to have the minimum needed soffit vents. The other attic has adequate soffit vents but only a turbine. I don’t really want to cut holes in my year old roof so I was considering adding a powered fan to exit thru the soffit. My idea was to run a couple lenths of clothes dryer duct to the top of the attic area, thru a fan, then out thru the soffit in an area where there are no intake vents. Does this sound workable?
May 28th, 2009 at 2:58 pm
I had soffit vents installed several years ago. Now, I’m at a point where the house needs a paint job. As I walked around my house inspecting things, I noticed that the openings in the soffit vents were pointed toward the house and the air it vented left a dirty area on the brick moulding below the eaves. Is there any reason I can’t just take those soffit vents off and turn them 180 degrees so that the openings of the vents point away from the house?
June 3rd, 2009 at 2:58 pm
Why should soffit vent openings point toward the house? Is it because windblown rain could possibly get in the attic if vent openings are pointed away from the house. It would seem that you would get better air flow if the vent openings were pointed away from the house.
Ben Erickson Says:June 4th, 2009 at 8:10 am
Hi Carlton,
This question has come up before and I haven’t been able to come up with a definitive answer. Your speculation about blowing rain being the cause is the only one I can think of, and, like you, I think the odds of that are pretty slim.
June 28th, 2009 at 9:06 am
My home is a colonial built in the in the 1930’s. It was about 3 years ago. The roof is about 15 year old and will need to be replaced in the not too distant future. However, in the interim, we would like to address the ventilation issue. When the previous owner had the roof replaced, a ridge vent was installed and soffit vents installed. The problem is that the soffit vents do not have visible openings in the attic. The attic floor is covered with tongue and groove boards, part of the original construction. Cellulose insulation was added some time in the past as well. What is your suggestion for connecting the soffit vents to the attic area?
July 18th, 2009 at 12:16 pm
Ben,
I was thinking it might be possible that the air current might move up the house to the soffit then outwards? Then
again I have never seen an air current analysis on a roof.
July 19th, 2009 at 8:30 pm
I need to install soffit vents in our home; several years ago we had 12 inches of insulation blown into the attic. Will this complicate installation of the soffit vents? The attic is small and difficult to work in especially considering the blown in insulation, is it necessary to be in the attic in order to install the vents or could this all be done from outside?
July 29th, 2009 at 5:12 pm
I need air flow in my attic badly. I took off two soffit vents only to find batt insulation from the vent back up to the inside of the attic. I don’t see a path for air flow? I have about three feet of slopped ceilings in each room that mirror the roof slope and the insulation is between the roof and the room ceiling.
Can I pull out the insulation, put in baffles and then blow in insulation arouind the baffel? I am also putting Radiant barrier on the underside of the attic roof.
August 2nd, 2009 at 11:31 am
I have a ranch house 90×30. I installed a new roof last year with a ridge vent; took out the old powered roof vents (ugly!). I have two gable vents at opposite ends of the house; about 4sq/ft each. There is perforated vinyl soffit material running the full length of 90ft under the soffit on the north side of my house. This covers the soffit board which has two 2″ diameter holes drilled between each joist. There are no soffit vents on the south side of my house. Three questions; first, are the 2 inch holes enough ventilation or should I remove the perforated vinyl soffit material and cut larger holes? Second, should I remove the perforated product completely because it it prevents the passage of air and is not efficient enough? Third, must there be a equal amount of soffit venting on both sides of the house? Thank you for any help!
Ben Erickson Says:August 4th, 2009 at 9:47 am
Hi Howard,
In answer to your questions:
The two 2″ diameter holes should provide enough air flow as long as they’re not blocked by insulation in the attic.
The continuous perforated soffit should allow for enough air flow.
Equal venting on each side of the house is a good idea to evenly cool the attic, and if it’s not too difficult to do, you might want to consider it.
Good luck with your project.
Ben Erickson Says:August 4th, 2009 at 11:34 am
Hi Andy,
Installing soffit vents can and often has to be done from outside due to space limitations in the attic.
Just be sure the insulation isn’t blocking the vent by pushing it out of the way when the hole has been cut so the outside air can flow into the attic.
August 8th, 2009 at 4:19 pm
hi, 16 yr old house. 7 roof vents, soffit vents all around. notice shingles curling above 1 room. attic is very hot.. how do i check to see if my roof and soffit vents are plugged? have had strong wind storms in past, one time attic trap was sucked up into opening. could this have disturbed the insulation in attic enough to cause plugged vents.?
August 23rd, 2009 at 11:11 am
I have a seasonal unheated cottege with a vaulted ceiling-the roof pitch is @5in 12(10″eaves)-at present there is no venting at all. I want to know if 1 gable vent on the back wall as high up as I can install it would be enough for this 400 sq.ft. building built on blocks
August 29th, 2009 at 12:05 am
When I did research on this I focused on net free area. I wonder why this article fails to mention net free. Based on your Danny’s example of using vent size alone, you will not let enough air in since the grills/screen take up space. An 6*12 soffit vent is not really 72 sq.” of ventilation but is only 27sq.” of net free area. This can make a big if you put in 10 vents but really need 30 vents. I am not a professional but would it makes more sense to me…
September 7th, 2009 at 11:40 am
I hate to repeat someone else’s question, but I cant seem to find or access the answer from B. Hanson’s question on
November 8th, 2007 at 1:19 pm (AND I need the same answer)
I am ready to do this plus add styrofoam ventilation channels. I am wondering if the ventilation channels go only where the soffit vents are or must I do all the roof rafters with the channel vents?
September 7th, 2009 at 11:45 am
Never mind – I see it now –
Kevin Says:
January 24th, 2009 at 2:42 pm
Is there an answer to B. hanson 11/8/07 re: how many baffle vents per soffit?
Your calc’s for # of required soffits is very helpful. Wondering if baffles are needed between all rafters or only those rafters over soffits.
Install soffits on ends and in middle for best results? Ie: need or 3 for 13 rafters.
Thank you.
Ben Erickson Says:
January 26th, 2009 at 9:38 am
Kevin,
Baffles are only needed in the rafter/joist spaces where soffit vents are located. If you have continuous soffit vents, install baffles in enough (or all) the spaces to give you the needed square footage of vent area. Space the soffit vents out so they divide the attic area into equal areas. In your case, I would put one in the center, then come in a couple of rafters on each end for the other two.
October 8th, 2009 at 11:45 am
I have a 1700 sqft ranch, when the roof was redone aprox. 10 years ago, we had a continous ridge vent installed, the 3 foot deep plywood soffits were removed and a continous vented vinyl soffit was installed the entire length of bothe the north and south sides,there are also 2 gable vents on opposite ends east & west sides each 2′H x 14″W. we have over the years had difficulty keep the house warm during the cold michigan winters. and have experienced outrageous energy bills. during the summer months we notice that the house also seems to go through a heat soak in the evenings that overwelms the air conditioned living space. Is it possible that too much ventilation could be causing incresed energy use, and causing erradic temperture fluctations. Oh I might add that on windy days it is impossible to keep any heat. The house always feels cold even when it is warm outside.
Also in response to an earilier post about vents above windows and doors, I was told that this should not be done, because in the unlikely event that a fire should occur the air currents would draw the flames into the attic causing more damage.
Ben Erickson Says:October 9th, 2009 at 7:56 am
Hi Randy,
Good point about fire and attic vents, thanks.
I wouldn’t think that too much attic ventilation is the problem. More likely the culprits are not enough insulation in the attic, doors and windows that aren’t energy efficient, not enough insulation on the HVAC ductwork (if it runs in the attic), or an undersized HVAC system. Plus, you do live in Michigan where it gets pretty darn cold in the winter!
October 10th, 2009 at 5:35 pm
Thanks for your reply Ben. I should have stated that the attic has an origianal r13 layer then I added a r30 layer a few years ago. furnace is 92% efficient installed in 1998 and all the windows have been replaced within the last two years. We do have a whole house attic fan that gets covered in the winter time. It seems the more I try to be efficient the higher the bills go.
Ben Erickson Says:October 12th, 2009 at 8:19 am
Randy,
Sounds like you’re doing everything right as far as energy efficiency goes. The problem with blocking the vents in your attic during the winter is that it might cause moisture to build up in the attic which could lead to mold and rot.