Does a Barndominium Need Soffit Vents or Not?

[racecougar]

You won't need the closure strips for the R-panel installed as your soffit. You could install vents in the R-panel that was installed as your soffit, or remove that R-panel and install perforated/vented soffit.

 

[SlippinJimmy]

You won't need the closure strips for the R-panel installed as your soffit. You could install vents in the R-panel that was installed as your soffit, or remove that R-panel and install perforated/vented soffit.

Oh okay, sorry I must've misunderstood. I guess the builder should've used the closure strips if it was the same R-panel on the roofing, but because of the standing seam, it's different. I was thinking I needed to seal any gaps there, then add "controlled" venting.

Aesthetically, I think I'd prefer the perforated soffit in the same color, but they said it takes about a month to get, and I don't know how easy it is to swap all that out--and at this point, asking my builder to do it seems like asking for more trouble. Drilling 6" holes with a hole saw and siliconing those round vents in there might be easier, but then I'd have to either paint match them, or hope they look "industrial" in natural aluminum... is it over yet?

 

[SlippinJimmy]

I'd aim for closer to 1:300, not 150, and ridge should never be more than 50%, better less, or it creates negative pressure in attic, not a good thing. Code with exception for 1:300.

R806.2 Minimum vent area.​

The minimum net free ventilating area shall be 1/150 of the area of the vented space.

Exception: The minimum net free ventilation area shall be 1/300 of the vented space provided both of the following conditions are met:

1. 1.In Climate Zones 6, 7 and 8, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.
2. 2.Not less than 40 percent and not more than 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located not more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically. The balance of the required ventilation provided shall be located in the bottom one-third of the attic space. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted.

There are lots of houses with minimum and much more than minimum attic venting that still have ice dams and mold in the attic. It's a had solution to a problem that has better solutions.

Okay, thank you. I was honestly thinking about the pressure aspect. I know that in building PCs, you generally want to achieve positive pressure in the case by having more intake fans than exhaust, so I guess the same logic applies here.

So 1:300 for 2560 sq ft is ~8.5 sq ft of ventilation. So without knowing exactly how to quantify how much of that exists within the ridge vent, it does account for some of that ~8.5 sq ft of total ventilation area, correct?

So if I take, say, 60-70% (since the ridge is a guess) of that and install ~5-6 sq ft of intake vents in the soffit, that should give me adequate venting with some positive pressure?

 

[billconner]

To use the 1:300, ridge must be less than half of total - between 40 and 50 percent. If you know source of ridge vent, you should be able to track down how much NSF. And you can block some.

Too much high - ridge - vent creates negative pressure in attic, and ***** conditioned air our. Wish positive pressure was possible in an attic.

 

[Kpaige]

That's what I've gathered from my research. Despite what even the metal manufactures themselves have told me, I can't understand how I wouldn't need soffit vents--unless there is indeed some phenomenon that takes place in metal buildings where indeed, sufficient air is drawn in through the ribs.

Other than a "wait and see" approach, is there some kind of test or something I can do to determine whether or not "enough" air is coming through there?

I put massive metal roofs on and designed the systems under them talking U of M hockey arena and such and many historical buildings along with pole style buildings. You need to keep space between conditioned area and unconditioned and the air flow keeps condensation from happening also. The soffit design itself along with proper roof vents creates the push/pull for ventilation. Whom ever the person is telling you this he has no clue how it works. We put massive warranties on the projects we designed and built and there is a science to proper air flow, proper vapor barriers, proper insulation. Properly done you will get the most efficient heating and cooling plus control the moisture so it does not cause issues down the road. I have seen attics rain in from condensation when there is improper ventilation and the warm air hit the roof deck and instantly turned back into water. That’s what happens when warm air hits colder surfaces like a roof deck in the winter. Almost all warm air contains moisture.

 

[SlippinJimmy]

To use the 1:300, ridge must be less than half of total - between 40 and 50 percent. If you know source of ridge vent, you should be able to track down how much NSF. And you can block some.

Too much high - ridge - vent creates negative pressure in attic, and ***** conditioned air our. Wish positive pressure was possible in an attic.

I'm going to try to find out the exact NSF on my particular ridge vent. However, I found a similar looking one online that stated 12 sq in (0.08 sq ft) per linear ft. So if I have 64 ft of ridge vent, I guess that's 64 x 0.08 = 5.12 sq ft, which using the previous 1:300 calculation of 2560 / 300 = ~8.5 sq ft, suggests there would be over 60% of the total ventilation coming via the ridge vent.

On top of that, my 18"x18" gable vent adds another 2.25 sq ft of ventilation. Granted, as the fan is thermostat/app operated, it could function as either an intake or exhaust, so would I split that 2.25 between the two?

If that's the case, it's over 70% exhaust, so should I add more intake vents then? I am in zone 4, and if I'm understanding it correctly, the code says to use the 1:300 you must meet both of those 2 conditions, and it sounds like I don't meet either one.

Otherwise, how would I go about blocking off the ridge vent to bring it into the ideal range?

This seems so confusing. It's definitely a science.

 

[Rc_Guy]

I think what you're seeing more than anything is that the post frame market isn't stick builders that are stepping into post frame, its ag pole barn builders trying to find a new market. The ag builders are used to building cheap as that's what their clients needed out of the buildings.

I built a kit for my first pole building and while the contractor offered the features I wanted on his bid sheet, he didn't have experience actually spec'ing and selling them. Standing seam being a different paint and black from the standard metal panel and enclosing soffit were all new for him.

I agree, that is why we had a house builder do ours, a pole barn company put up the pole barn but the house builder did the rest.

 

[SlippinJimmy]

Whom ever the person is telling you this he has no clue how it works.

At one of the places I called, it sounded like the "salesperson" just left their job at the movie theater or something. They were simply telling me what they'd been told to say, without any understanding of why they were saying it.

 

[rancherbill]

.....it's up to you to ask the right questions and become the detective--not to just go home and take the pill, but to understand what they're trying to accomplish with the prescribed treatment, as there may be a natural, safer, and quite possibly more effective alternative.

No one can care about your health as much as you do--just like no one cares about your home or car or whatever as much as you do.

If you're Youtube Doctoring yourself you have an idiot for a patient.

Youtube Doctors caused death with Covid, caused death and illness with the antivax stuff and the list goes on and on.

Why didn't you hire a bunch of grade 10 kids to do your work. They could have learned everything on Youtube. You hired your guy because of experience - TAKE IT.

 

[racecougar]

Why didn't you hire a bunch of grade 10 kids to do your work. They could have learned everything on Youtube. You hired your guy because of experience - TAKE IT.

Have you read what the builder has stated (via the OP) in this thread?

 

[SlippinJimmy]

If you're Youtube Doctoring yourself you have an idiot for a patient.

Youtube Doctors caused death with Covid, caused death and illness with the antivax stuff and the list goes on and on.

Why didn't you hire a bunch of grade 10 kids to do your work. They could have learned everything on Youtube. You hired your guy because of experience - TAKE IT.

Hmm... Well, at least we know where you stand on all that. I appreciate your input. Agree to disagree, friend.

 

[Kpaige]

If you're Youtube Doctoring yourself you have an idiot for a patient.

Youtube Doctors caused death with Covid, caused death and illness with the antivax stuff and the list goes on and on.

Why didn't you hire a bunch of grade 10 kids to do your work. They could have learned everything on Youtube. You hired your guy because of experience - TAKE IT.

Some are very good at appearing to be good contractors and can say all the right things but when push comes to shove and the workers are on site don’t have a clue!!! I am one of the best not because of what I know but my willingness to adapt and learn it’s about my name not the $$$$ not a lot of people left in the world like that.

But that’s ok take this moment to throw out politics that have nothing to do with the discussion.
I also agree to disagree with your opinion.