attic vent

[purevil115]

Hey everyone i just finished my detached garage and have a few questions for when it gets warm out. My attic has no ventilation whatsoever no soffit over hangs to cut in, and no ridge vent. What should i do to vent it this spring. gable vent and some of those vents on the side of the roof or just the ones on the side of the roof or the wind kind i just dont know.

 

[Coleman396]

Is it insulated? I would suggest putting a couple of the whirly gig vents up there.

With out some kind of good venting it will be super hot in the top leading to a premature roof failure,discomfort with the heat of summer and then good old black mold when it gets cooler. You cannot have too many vents in the attic!

 

[purevil115]

yes its well insulated. so i know something needs cut in this summer

 

[JakeKohl]

Actually, winter ventilation is at least AS important as summer in a home...not sure over a garage, though. Moisture tends to accumulate in the attic in the winter - particularly on the cold roof sheathing and it WILL sweat if a cold night meets a warm attic. This leads to mold (i.e., not too good of a thing).

The type of ventilation you use depends on where you live - in northern climates with cooler summers, ridge vent or other static roof vent fixtures combined with several sofit vents is fine (mostly to move some air and exhaust the moisture). In southern climates - definitely in florida, powered ventilation is the recommendation to help manage the large heat load in the summer - again with a ton of sofit vents. Gable vents are on the way out because they short circuit the natural bottom to top convection you would otherwise achieve with sofit vents and some sort of ridge or other high-mounted vent.

Make sure your sofit vents can't get clogged with insulation.

 

[awdblazer]

you will probably have to use roof vents for intake (close to your eaves) and then use them also for exhaust

 

[socapots]

Like they are saying.
I have a poorly vented attic on my shop. And when I have the heat on for a day it starts melting the snow off the roof.
Not cool.

 

[5lima30]

I used end gable vents in my insulated garage. One end (North side) I installed a thermostatically controlled exhaust fan. It works great! Even when it was 85F outside (w/ no shade) it was a comfortable 74F! Prior to insulation and fan it would be 90F inside.

 

[NUTTSGT]

I have been told to use ridge vents with soffit vents. Gable vents are to be used with roof vents. This is what I have been taught, I'm sure opinions vary.




FWIW, when I say roof vents, this is what I mean, something similar to these.

http://www.homedepot.com/h_d1/N-25e...053&langId=-1&keyword=roof+vent&storeId=10051

 

[R6 Racer]

As I read your OP your building has no soffit at all making soffet vents impossible. If that's the case I believe you will need to use some kind of power exhaust system as 5lima30 suggested. I would put a gable vent with a power exhaust up high on one end & put a few (2 to 4 depending on size) vents for air intake low on the opposite gable end. I might even put 1 small intake vent down low on the exhaust side.
However you do it, do something very soon as it doesn't take long for bad **** to happen up there with no air flow.

Steve

 

[Addrock]

Don't ask season and climate specific questions if you don't provide your region or state. If you don't have it in your sig, then provide it in your construction question.

 

[rburke65]

Yes, your geographical location would help. You can post it in your profile. I don't understand why this is not required to register, as this question is often asked and is a big waste of time in many posts.

 

[haugy]

My problem is the shape of the corrugated steel makes getting a good sealed vent installed tricky. I have no soffits or ridge vents either (didn't know I needed them). Now I'm trying to ventilate my roof as well so I can put insulation down on my ceiling.

What are you guys with steel buildings using?

 

[purevil115]

I live in ohio. no soffits so thats out. sounds like i will have to run s gable vent at one end and a powered vent at the other. I dont heat it right now but soon as spring comes i am for sure cutting in some vents of some sort. With what i want it should bring in air at one end and expel it at the other. I was hoping for a non powered route but looks like this may be my only option.

 

[purevil115]

I just dont know the best route to go with this. I would prefer a static type vent but without a soffit vent I dont know how to get hot air from bottom of attic to the top.

 

[NUTTSGT]

No soffits at all or no soffit vents ? How about posting up a picture of what you have.

 

[haugy]

I just dont know the best route to go with this. I would prefer a static type vent but without a soffit vent I dont know how to get hot air from bottom of attic to the top.

I know this may sound ghetto or goofy, but I've been trying to find something that would allow airflow, but yet be shielded from letting rain in.

Since my steel has intricate contours and I would play hell with getting it sealed up right (I **** at wood work). I've been looking at dryer vents. You know the covered vent that has a small tube inlet into the house? Hole saw a hole, fit the vent in, and seal it up. Then just remove the flap closure on it so it's open all the time. 2 of those would allow a lot of air flow if you put them low and had a vent at the top. I plan on putting two of them low on the windward side, and two of the high on the leeward side. That should allow the convection effect and the natural wind we constantly get to move the air through.

It wouldn't be the best, but it should help regulate the air enough for when I insulate the ceiling to keep moisture down.

 

[purevil115]

It gets even tougher the back of the building is brick all the way up to the roof in the back so cutting in a gable is even tougher. zero soffit to speak of and only the front is wooden. The front has a huge opening to access the attic. It houses some storage stuff and the furnace for the shop.
front:

back

 

[IHI]

If I were to bid this job it would be a static vent on 1 gable and a thermostatically controlled power vent in the other gable. Being brick on the back seems daunting, but it's not a big deal. You can rent a quickie saw to cut the hole and use a cold chisel to finish out the corners that will be left the saw blade cant get at for obvious reasons.

Then you can just a diamond blade for a 4" grinder and use that to cut reliefs n the brick to install your flashing so no water gets behind the brick.

FWIW, I seen the whirly bird roof vents recommened above, there is no way i even considered using them on customers homes, they are literally nothing more than a big hole in the roof that will allow wind driven rain/snow into the attic space. I know alot of DIY'ers install them thinking they are the cats meow, but we have repaired alot of drywall/plaster, and moldy roof sheeting thanks to these ridiculous products...how they are even allowed to be sold is beyond me, but they are and folks that dont see the damage they allow to happen on a consistant basis are none the wiser, because let's face it...how many folks regularly crawl into their attics. We had to since we'd get called for ceiling repairs, so once we got in the attic to find the root source, it'd lead to other problems that needed adddressed as well.

 

[purevil115]

yeah i know i can cut into the brick for a gable vent. I guess with my attic going powered is the only option. how long do the fans from homedepot last.

 

[IHI]

That is the million dollar question on fan life, so go many years with no issue, others seem to only last a couple years. Seems through talk on my contractor forum, region plays a big factor in fan life, the places seeing shortened fan life are typically southern regions where sun exposure really makes the attic a oven type environment constantly.

So take that for what its worth, wish I could say it will last 10yrs at least, but everything I've ever read on them points to a case by case scenario. My only advice, install a switched outlet near the fan, and install a cord with a plug on it so if and when it does **** the bed, swapping it out will be extremely fast and efficeint.

The only other viable option which we have done, when the roof needs to be replaced, add tails onto the rafters and give yourself 12~24" eave overhangs, that way you can then install a maintenance free draft system with the poly chutes in everry other rafter cavity and a ridge vent

 

[NUTTSGT]

That is the million dollar question on fan life, so go many years with no issue, others seem to only last a couple years. Seems through talk on my contractor forum, region plays a big factor in fan life, the places seeing shortened fan life are typically southern regions where sun exposure really makes the attic a oven type environment constantly.

So take that for what its worth, wish I could say it will last 10yrs at least, but everything I've ever read on them points to a case by case scenario. My only advice, install a switched outlet near the fan, and install a cord with a plug on it so if and when it does **** the bed, swapping it out will be extremely fast and efficeint.

The only other viable option which we have done, when the roof needs to be replaced, add tails onto the rafters and give yourself 12~24" eave overhangs, that way you can then install a maintenance free draft system with the poly chutes in everry other rafter cavity and a ridge vent

Glad you chimed in, you had a damn good post over at YB a while back, I copied and pasted it another thread.

 

[IHI]

Glad you chimed in, you had a damn good post over at YB a while back, I copied and pasted it another thread.

Lol, YB members are like the plauge....or a cult we're everywhere lol

 

[purevil115]

so thats what i am going to be doing it looks. cutting in 2 gable vents. The front will be easy the back will be tougher. I will just be cutting the brick with a cut off wheel or atleast scouring it and then using a chisel and hammer to break it out of the way. I may try it without a fan at first and see what it does. Im sure in the middle of summer a fan will be needed.

 

[purevil115]

When you say use a diamond blade to cut the brick for the flashing what do you exactly mean.

 

[IHI]

so thats what i am going to be doing it looks. cutting in 2 gable vents. The front will be easy the back will be tougher. I will just be cutting the brick with a cut off wheel or atleast scouring it and then using a chisel and hammer to break it out of the way. I may try it without a fan at first and see what it does. Im sure in the middle of summer a fan will be needed.

Do yourself a favor now before game planning, find an online venting calculator, or google "what size gable vents". If going static vents, you will find that to be effective...they will be HUGE holes so I honestly think a fan unit is about the only viable option.

It'd be like having a breathing tube...what's going to allow more air, a mcdonalds straw or a 5/8 id tube

 

[purevil115]

so i can go smaller on the vents if i get a fan unit behind the one blowing out.

 

[purevil115]

wow so i did the calculation and need about 3 times as much gable vent free air space as the biggest one home depot sells. I dont know if this was static or with a fan but my garage isnt that big so this seems weird.

 

[readhead]

Hold on. You said that the furnace is in the attic. It should be in a conditioned space. I would insulate under the roof. How is the furnace getting combustion air?

 

[purevil115]

How does any other furnace get combustion air, trust me its not air tight in the attic. I do hvac for a living theres more than enough air in that attic to work. There are millions of furnaces in attics similar to mine. With the furnace in a horizontal postion and the insualted ducts going to it, it really doesnt need to be in a condtioned space. rooftop units i work on are outside in the cold.

 

[JakeKohl]

yeah i know i can cut into the brick for a gable vent. I guess with my attic going powered is the only option. how long do the fans from homedepot last.

I put two on my roof three years ago...one quit working after a year. The other is still working. I need to get up there and replace that other unit. I sequenced the thermostats so one would come on at a lower temperature and they both only came on when it really got stinky hot up there.

 

[readhead]

I was a union tinner for twenty years. I know you can put a furnace in an unconditioned attic but why would you want it to work that hard. An RTU is made to live outside and most of the time the duct in and out of the curb is in conditioned space. I would still insulate under the roof deck and bring the furnace inside. The whole heat affecting shingle life deal was debunked several years ago. A study awhile back showed that the common assurtion that air automatically goes from eave vents right to the ridge vent was untrue. There was a dead zone in the middle of the attic. Of course the hot air did exit through ridge vent but it was mostly because of the stack effect from leakage through penitrations in the house. If the attic is as leaky as you say the easy solution is to place a few vents on one side of the ridge out of sight and leave the furnace outside.

 

[purevil115]

Well it was in the shop for a while but i wanted the floor space back. It costs me like 10 bucks a month in gas to heat the garage. My static pressure in the ducts is less than normal house setups and my amp draw is super low. The furnace is not working hard at all. IN fact have the furnace in the conditioned space take heated air and just expels it into the exchanger right up the exhaust pipe. The whole cabinet is insulated and all the flex and boxes for the grills are insulated. Its not ideal to be in a attic but theres upsides to it as well.

 

[purevil115]

In reality that front access door on the garage leaks like crazy. I can probably cut into the door with a gable vent into it and cut a hexagon shaped on in the back with the fan. This should work really well for expelling the heat.

 

[IHI]

Lol, somebody better send this thread to all commerciaql building owners and the millions of homeowners with house on slab construction with the furnace in the attic and let them know how crazy this idead is and corrdin off a room to bring the furnace back inside lol.

Heat kills shingles, period. It cooks them on both sides and that is why the only roofing jobs I sold were the jobs we got to address venting issues.....there are plenty of hack roofing crews that all they know is lay up shingles to make it pretty for the now, cash the check and who gives a **** if they last 20plus yrs. I always bid a system, was always told I'm the only guy that needed inside the attic when measuring, I sold my jobs at mid high to high but the clients that we worked with got a job done right for the long haul...and venting makes or breaks a shingled roof~literally, especially with todays shingle consturction.

 

[readhead]

Check the shingle manufactures warranty. Most now omit venting as a requirement. I have installed furnaces in attics and they work. But in this day and age we know better. Of course an attic needs to be vented and in this case a few vents in the gable or roof will do the job.

 

[purevil115]

Will you come to ohio and vent my garage lol

 

[readhead]

You bet. Send me a ticket.

 

[5lima30]

yeah i know i can cut into the brick for a gable vent. I guess with my attic going powered is the only option. how long do the fans from homedepot last.

When I wa looking at them the ones they had at the box stores were made in China ! I actually found one at Nothern Tool that was on sale for about $70 shipped to my door and it was made in USA!

 

[purevil115]

Thank you i was hoping someone knew of a decent place to buy from

 

[purevil115]

Looks like all gable vent fan i see are for a full size house needing 600 square inches of intake air to work. I see they have a solar powered unit that only needs about what i can offer out of a gable vent, I may really not sure what my best route will be. Or i get a full size one and use basically a dimmer switch to slow the motor down but then i am sacrificing the life.