Venting attic on pole barn

[Smokingthemidwest]

Hello everybody,
The house that i bought had a 24'x32'x8' metal pole barn as the garage. I am pretty excited cause that is my first house with a garage. Well this summer i got the concrete poured for the floor. My question is regarding when i finish the inside of the garage. The garage has gable vents on both ends but no soffit vents because of no overhang on the garage. I want to finish the inside but don't want to cause a moisture or excess heat in the attic problems, any ideas? Thank you in advance

 

[73RR]

"finish the inside" means what?
Pole barns typically are not very tight so a powered gable vent might be all that you need but a few more details would be useful.

 

[Smokingthemidwest]

Sorry, by finish i was thinking about insulating the walls and ceiling. I was thinking about putting up tin or osb on the walls and ceiling. I want to be able to heat it when i need to work on something on the weekend.

 

[rburke65]

I don't understand why you would even need heat in your location......oh wait......we don't know your location......never mind.......

 

[Smokingthemidwest]

I don't understand why you would even need best in your location......oh wait......we don't know your location......never mind.......

Wow!!
"I don't understand why you would even need best in your location"
What does that mean?

I fixed the Location. I am just trying to get ideas of how to vent the attic. I was thinking about an automatic gable fan but was not for sure if that would be enough or not.

 

[493 scamp]

Welcome! I am about 50 miles south of you and have a 32X40 polebarn with no overhang as well. How are you going to keep the insulation away from the edges? I was looking at the preformed foam vent baffles but my trusses are 48" on center so would need 2 attached together some how. I am using metal for the ceiling and undecided on walls. Was planning on blow in cellulose in ceiling and fiberglass in walls. I know I will need more vents at the top but figured the unsealed roof to wall area would let enough air in at lower edge. Is yours like mine and nothing sealing roof to walls?

 

[matt_i]

"finish the inside" means what?
Pole barns typically are not very tight so a powered gable vent might be all that you need but a few more details would be useful.

One concern would be a bare metal skin on the roof, because even with a nice good layer of ceiling insulation, you could still get into the situation where there's warm humid air trapped in the attic and then a cold rain falls outdoors, which starts condensation on the bare metal skin causing it to rain inside or drops to roll down....

The spray foam, while costly, would solve that problem....but then you might be better off to block the gable vents and keep the inside sealed.

 

[rburke65]

There...fixed it. I installed plastic sheeting on my ceiling THHN metal ceiling panels and blue fiberglass insulation on top of that. To vent you are going to need a fan large enough to move approx. 800sq.ft......the size of your building I believe. And you will need to have a gable vent large enough to supply the make up air. Lots of info on Internet on attic ventilation and formulas.

 

[Jake40]

If you have a gable vent in each that's all the ventilation you should need. When gable vents are used you don't need vented overhangs because it disturbs the air flow. On your ceiling just install a ceiling and use a faced insulation, paper towards the inside of the building. We don't recommend to put plastic on the ceiling or walls because it can cause moisture issues inside the building.

 

[rburke65]

Does the faced insulation qualify as a vapor barrier?

 

[Cyberbear]

I used a powered gable vent on a thermostat that worked well to cool my upstairs area and attic space. The major problem I had was the fan running constantly during the summer months and getting a much higher electric bill.

 

[73RR]

If you spray foam the roof assembly, including the gable ends, from plate to plate, and assuming that the walls are insulated, then the ceiling will not need insulation and condensation is gone.
https://www.whysprayfoam.org/get-the-facts/

 

[lakeroadster]

If you spray foam the roof assembly, including the gable ends, from plate to plate, and assuming that the walls are insulated, then the ceiling will not need insulation and condensation is gone.
https://www.whysprayfoam.org/get-the-facts/

And if you ever have to replace the steel panels, due to hail damage, etc., it will be a nightmare due to the spray foam.

As far as "condensation is gone".. opinions vary. If you have a warranty on the steel panels, spraying foam on them is problematic:

"Most foam companies are not willing to provide written guarantees that their product will not cause problems and that they will stand behind any damage that may happen."

"Most roofing companies will void or waive their warranty under these circumstances."

http://www.greenhomeguide.com/askap...ion-directly-to-the-underside-of-a-metal-roof

Additionally if spray polyurethane foam is used it must be protected by a thermal barrier such as 1/2" gypsum wallboard. http://sprayfoam.com/content/spray-foam-faq-for-homeowners/48

 

[73RR]

And if you ever have to replace the steel panels, due to hail damage, etc., it will be a nightmare due to the spray foam.

You'll find this hard to believe but some folks actually sheet the roof structure

 

[lakeroadster]

You'll find this hard to believe but some folks actually sheet the roof structure

That's not a typical practice with a pole barn, which is what this thread is about.

If the deck does have wooden sheathing with steel panels on top, most folks would find it obvious that placing foam under the sheathing will have no impact on the ability to remove the steel panels.

Signed,

Captain Obvious

 

[Buck41]

I used lumber wrap to keep the insulation out of my truss vents. It's free at any lumber yard and its waterproof. Just cut and staple it up.��