Residential attic ventilation

I have a dumb question.

How did the evolution of attic ventilation responsibility land on the roofers' lap? I had a home builder ask us to provide attic ventilation on a custom home.....WTH?

I can't recall, who had previously made the comments, on how "accepted practices" come about...Possibly they'll chime-in here. Anyhow.....

It amazes me as to how roofers have taken on the responsibility of attic ventilation. I suppose it's a regional thing, as well as re-roof, (prime contractor), vs. new construction, (subcontractor), dynamic.

Attic ventilation, is absolute calcuable, as per IBC/IRC. Anything beyond that, should be referred to an authentic HVAC professional. HVAC contractors have engineers on staff for that purpose.

Roofers should understand the liability they are exposing themselves to. Can you image what a court would do to a roofer in a construction defect/mold situation? Here we have a roofer, who simply unilateraly decided, by the seat of his pants, how to vent a particualr attic...The opposing litigants have HVAC professionals on their team.....Yikes!

Just a thought.....

It sets us apart and it adds real value. I have tried to teach other roofers around here and very few will take the time to learn. Details aren't for everyone I suppose.

Wywoody.....That's crazy! However, I can understand....Here, they've run bath/kitchen vents right into the attic spaces! I would hope that doesn't go on anymore, w/new construction....Haven't checked lately.

O/S......Most of our work the last couple of years has been general construction...and yes, as with re-roofs, we sometimes address venting...However, when you take on that responsibility, one needs to have it absolutely covered....So I understand what your talking about, and your definitely doing the right thing.....To reiterate; You are esentially taking on two different trade aspects...Roofing & HVAC.

Oh! and the roofing material manufactures meddling with their venting recommendations.....They could very well end-up with thier teet in a wringer one day & have to give up some pie!

Part of our reroofing "spec" is locating bathroom vents and then venting them via a flapper vent directly to the outside. Total ventialtion, of the attic, especially at the soffit. We are carpenters also and that helps. I am appalled at the vents that CT has made that fit along the bottom of the roof. They look like crap, they will leak and they ignore the problem. They are somewhat roofer "friendly" though, so we are seeing more and more of them. They do noth8ing for the insulation that is touching the bottom of the roof deck; very important. We are always 2 to 3 times as expensive as someone that is going to just reroof, and we still get the jobs. I DON'T want all of the jobs. Heck, I don't want most of them and I refuse them. small is beautiful, and quality and value are most important.

Around here, the V in HVAC only refers to getting bathroom/kitchen air out of the interior. In fact, it is not unusual for them to run their vent lines up to the roof vents and "commandeer" 20 to 30% of the existing roof ventilation, all done long after the roofer is gone from the site.

Egg; Agreed....I was trying to maintain an abreviated version (LOL)......In my round-a-bout way, I was simply attempting to point out the possible implications/liability of unnecessarilly assuming responsibility for something that really doesn't have to be, and virtually, is by trade definition, anothers', (HVAC).

Understandably, in this narcisistic/"pie-eating" society we must live & work in, risks are always there...Why not reduce the risks if one can?

For reasons stated, we're very explicit, to exclude ventilation design, in our contract agreements. We'll install it; Just not "design" it.

Out here (in Ca) now, every set of prints has to have ventilation requirements posted. That means intake, exhaust, type and location of vents. A rudimentary numerical calculation to explain the notations. All part of the Title 24 business. Insulation is also specified. That takes a lot of the guesswork off the table. Best to walk yourself through those, though.

Nothing so far has been hammered down on reroof, over-the-counter permits, at least in my zones. But people are jumpy and lawsuits are lucrative for some segments of the working population. Meaning, to put it bluntly if not cynically, plans and specifications or no, if you are working on any project today you may well become a member of the great American pie-eating contest tomorrow. This is a high-stakes, nominally civilized activity where entry fees are not required. All one needs is to have been in vague proximity to a supposed blunder in order to be entitled to a piece. Nobody goes home hungry. It's like playing pin the tail on the donkey where everybody gets a tail and you hope that yours is just one of the small ones.

Making claims to quantifiable expertise you may not have is not a very good idea, but neither is complying with expertise you know (or should have known) will or even merely may fail. You can get the white hat smacked right off your head just for having presumed to wear it, but you can also get smacked for not having put it on. You really really need to know your customers, know your terrain, and develop your instincts. Definitely know when to walk and have the strength to support that knowledge with appropriate action. As a clarinetist once remarked to me when I asked him how he felt after his solo performance, "It's a rush." I still get a thrill out of some of this stuff. And to think excitement can sometimes hinge on something as trifling as whether or not to install a little piece of hardware just there or just there.

If it fails, you aren't allowed to claim you were just there. Down the road a piece, even smart people (especially, smart people) have an amazingly tough time "recalling" just what went down, why, and where. There are times when merely living requires an act of courage. My take is a bit like OS' in that if you know your beast, ride him, and if someone tries to take you down for doing what you know is right, it's an honor to die for your principles. By the same token, if I doubt the veracity of a spec, I will politely question it and if the specifier is cheesy in reply, it's game over, no matter what his credentials.

OK O/S

The Truth? Don't let the insulation touch the bottom side of the roof. EVERY panel in the soffit is vented! Proper vents in EVERY bay! Ridge vent with external baffles on the peak. When the length of the ridge gets to be about 1/3 of the length of the eave, you had better consider a power vent. DON'T mix different kinds of ventilation. Vent your HVAC outside and let the air in the attic move where it wants to, but it better be moving all the time. Not one engineer in 1,000 has ever installed a roof and I can eat them for breakfast. If I can't do a re-roof my way, I din't do it. The results speak for themselves. No leaks, no ice and no mold.

The "code", (I believe both UBC, as well as IBC & IRC), used to be, (for the past 30 yrs anyhow); 1/300 if equal lower-upper,(eave/ridge) 1/150 if ridge/upper only

"MY" thoughts?.....I dunno...never done a study....It's definitely, ancient technology, that came up with it, as that's been the "rule", ever since I started back in late 70's......Maybe a roofer did...LOL

I suppose one would take the most restrictive/ill-ventilating friendliness type situation, as a "control".

There may be logical/authentic studies out there? Then again; Maybe not....LOL....Job security...LOL

As for the framers cutting holes...That's all they should be doing...Cutting holes. Not deciding what & where...That's up to the HVAC prof....GC has no clue as well....Roofer simply installs as per HVAC design.....Worked just peachy in California. It's a cluster-you know what here in Colorado, where no one really knows or cares.....Hence the const. defect issues.....This is a fairly arid climate, but the mold/rot is unbelievable.....Then we get into stucco & masonry nuckleheads.....Don't get me started

Re: New Construction Framers, cut lumber and nail it together. I guess that they do cut out vent holes too

Not sure where the HVAC guy would fit in during the soffit installation. Should he supervise it, design it or install it? How many exhaust hoods / flap vents in bathrooms get vented out the roof on new construction? LOL---One of 600?

The roofer is only installing exhaust components. And yes it is guesswork as to how much NFA, which product, etc. Prolly min code. Maybe not. The soffit is where they do the most guessing. Vent every 3rd or 4th panel? Maybe every 7th?

With RV, Baffles and NFA don't even play into it. Just "Ridge Vent". Speaking of baffles how about proper vent chutes...... every 3rd or 4th bay OK???? every 5th one? More randomness

Should the plumber shingle in the pipes too? The mason shingle in the chimney?

Seriously, doesn't the liability fall onto the builder? the inspector? who answers for code issues?

Seems like there should be specs included, monitored and documented........Basically some co-ordination *******************************************************

On replacements, very few really get into it here. Add unvented ridge vent? Sure, why not. LOL Mostly they are "selling" shingle replacements only.

Those of us that try to promote and keep warranties intact get a little bit of lip service from the manufacturer. No help from building departments either ( less than min. code gets grandfathered in: But make sure you are buy a permit......) * * * * * * * *

Hey TomB, what are you thoughts on AirVent promoting 1/150 vs. 1/300 code?

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My point is that your taking on the HVAC role/liabilities.

Most of us, that have done this for any time, know and agree with what you stated, simply through experience......However, why does the GC/HVAC/Architect/Engineer/designer, off-load this on the roofer?

I remember back in the late 80's, in California, there were "energy" laws/mandates that came about...Every home had to be specifically energy-calculated, by an HVAC engineer....The idea of a framer or roofer simply guess-by-golly, designing attic ventilation, was preposterous.

With shingles it is simple. We do it because no one else seems to have a clue. If you just treat the roof as an umbrella instead of a closed system it works a lot better. Air moves where ever it wants to and that solves all of the problems.

On new Construction, the trusses play an important part in that most of them have the "energy heels" that allow a full 12 inches of insulation and still leave 3 to 4 inches of space for the air to flow through. You must have a fully vented soffit (carpenters and architects) and then make sure and fully vent the ridge. If it is one of those large hip roofed homes with very little peak length, I recommend a power vent to move the air. Other than that, a full ridgevent using the AirVent II works best.

On reroofs, it is an entirely different story. We tear out the old soffit, install proper vents into the attic and then install a fully vented soffit system. On the roof, we fill in the old roof louver holes, close off the gable vents and take out any other vents (Turbines, power vents etc.) and then install a full ridge vent. Air in, Air out, new flashings, no problems. I don't care if there is grace over the whole roof or synthetic felts or no felt. I doesn't make any difference if the roof is totally vented and the air is MOVING!!

I used to do the very same thing, for the very same reasons.

These days I've noticed roofers, as well as shingle manufactures, taking on more attic ventilation responibilities.

With the widespread use of ice & water shields over the past decade or so, we're really experiencing exponentially more ventilation/mold issues.....It's going to get real ugly.

Around here, the framers usually cut the holes as per plans. However, for tile they have the mindset that "the roofers want to cut their own vents to fit their layout". I try to catch the framers while they are onsite and tell them I want the them to cut the holes and tell them how far down from the ridge I want the top of the hole to be. Since it is rare to have less than a full piece of tile on the top course, it isn't that hard to give them the measurement needed for a particular tile. I do this mostly to avoid the liability issues you mention.