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This is a test rant for a future video that may or may not happen.

But seriously, I cannot fathom how HVAC stuff in attics (or crawlspaces!) got normalized. Especially in new construction.

You virtually never see that around here (the most common application is old homes with radiators for heat who want to add central air) and for good reason!

@TechConnectify You’re not wrong, you’re just advocating the wrong solution. Conditioned attic spaces with insulation under the roof deck is the best approach for slab on grade new construction with high solar loads and AC demands.

@transcendentape But that's the thing, isn't it? A conditioned attic space becomes a conditioned space.

If you want to spend the money to turn it into one, I ain't gonna stop you. But most people just leave their attic an attic for one reason or another. And if that's the route they've chosen, ducts and the air handler should go somewhere else.

Plus, in many of the homes I'm talking about, the attic ain't tall enough to turn into a useful space anyway.

@TechConnectify The point of making an attic include d into the conditioned space isn’t to reduce the relatively minimal AC losses, it’s to deal with the condensation that results when an attic that reaches 150F and 80% humidity reaches an interior space conditioned to 75F or so. Your solution doesn’t address the fundamental problem we deal with in the South where we have night-time temperatures higher than desirable, high humidity, and no basements.

@TechConnectify What is fundamentally different between a wall and a roof? A wall can be shaded from the vast majority of solar thermal load simply by building overhangs. The roof cannot.

@TechConnectify So, instead of continuing the building scheme we’ve used since before there was A/C, it’s better to remove the pressure cooker that is an attic entirely. Is it cheap? No. But in new construction, the price differential is a handful of dollars per square foot and in my area, far superior than any other alternative.

@transcendentape I mean, if you want to remove the attic space, go ahead.

But understand that for homes around here, *NOTHING* goes in the attic. The attic has tons of vents at the eaves and the peaks to keep air flowing through it. Does it get beastly hot up there when the sun shines? Absolutely! But there's a layer of R-50 insulation above the ceiling to battle that intrusion.

And that beats the pants off of any insulated ductwork.

@TechConnectify I mean, go ahead. We live in entirely different climates with entirely different residential construction norms.

@transcendentape my central point is that I think people in different climates could learn a thing or two from us. Our summers can be just as bad as down South, if less consistently. Perhaps that's the only reason our attics don't get moldy, but I'm doubtful.

You pointed to duct losses as minimal, but the first estimate I found puts them at 25-40%. That's a lot of energy being wasted and money being spent to condition space you're not in.

We just... don't do that.

@transcendentape our M.O. has largely been to treat the attic as a space which is there to frame the roof and that's it.

It's functionally outside, so once the sun sets the conditions up there equalize with the outdoors quickly. And sometimes we even use a fan controlled by a thermostat to force some airflow! But that's relatively uncommon.

From my perspective, the reason we don't deal with mold is mostly that there's nothing up there colder than ambient temps.

@TechConnectify “It’s functionally outside”

This gets to the heart of the matter. I don’t think you appropriately appreciate how bad attics are in my climate.

Pre-A/C, homes were built with 10 or 12 foot ceilings and windows to allow cool air in the bottom and warm air out the top. When we got A/C and started insulating walls, we ran into all kinds of problems with mold. Walls can be protected by rooves, but there’s nothing to protect the roof.

@transcendentape Well, to be honest, I'm confused by what you mean by "bad attics." Can you elaborate?

But to circle back to the climates things, when you say "started insulating walls" - this is it right here. We've been doing that *forever* because we have to. And absolutely critical to that is a nice thick blanket of insulation above the ceiling. It doesn't really matter how hot the roof (or attic) gets when you have that barrier in-place.

@TechConnectify As a matter of fact we have not been doing that forever, at least in my climate. This is precisely the confident ignorance that I am upset with you about.

@transcendentape OK... let's rewind, here.

This whole discussion is about regional/climactic norms. It started with my challenging them, and you described what's done in your area as "the best approach"

Really, all I'm trying to do is challenge that, and offer up what's been normal here for a long time as an alternative. Perhaps, if someone ventured to try building a home down there just like we do up here, it would be much more comfortable and take less energy to cool.

But, perhaps not.

@TechConnectify You could test that hypothesis by observing what good homebuilders are building.

Matt Risinger is an Austin,TX homebuilder that deals extensively with these kind of questions, and he has a Youtube channel that covers a lot of the issues we’ve covered.

@transcendentape I'm familiar with those channels, and Risinger specifically! I largely like a lot of what they feature, but there's other things I totally don't.

For instance, I think tankless water heaters are extremely overrated and a barrier to home electrification. And I'm still perplexed by the attic thing - I need to log off soon but I want to repose my thoughts here on last time in a different way:

@transcendentape What does the air handler do? It produces the cool (or warm) air that you need, and it costs you money to use it. Therefore, that air has a raw dollar cost and you probably want to minimize waste.

This is the raw crux of my whole deal. It seems entirely self-evident to me that you should put the machine that costs money to use inside the space you want it to heat and cool. And, you should keep all components of that machine (i.e. ducts) in that space, too.

@TechConnectify I mean, yes. We are arguing the same point. The difference is that in the south, where nighttime temps are frequently above ideal and humidity is an issue, moving the structure of the A/C down to the liveable area doesn’t solve the problem. In fact, it makes it worse. The problem in the South is the existence of unconditioned attic spaces.

I’ve never walked outside to -20F temps.

I have seen a cloud below my ceiling due to dewpoint.

@TechConnectify What you might not be appreciating is the very different response water vapor has between-20f and 80f versus 150f and 80f

@transcendentape Oh no, I appreciate this but... again, in the summer this absolutely something we deal with. And to be honest, I feel like putting a cold thing in the attic is /way worse/ than not doing that.

In fact, why is keeping the AC entirely in the conditioned space worse? I need you to explain that because truly I'm not seeing it.

Our homes just flat out don't have ceiling penetrations into the attic other than an access hatch and electrical boxes. The attic, as I said, is outside.

@TechConnectify “Why is keeping the A/C entirely in the conditioned space worse?” Because in my climate, in conventionally built homes that aren’t built to the standards that we both are advocating for, those losses are necessary to ensure the attic doesn’t become a pressure cooker.

@transcendentape ehh... to be honest I still think there's something we're talking past each other on, here.

In my head, you can take any existing home where you are, get the HVAC out of the attic and run ducts below the ceiling, then patch up all the holes, add the sea of cellulose that's normal up here above the ceiling, and you'd be right where I want you to be.

No mixing at all of conditioned air with attic air, and sufficient ventilation prevents mold.

Am I missing something?

@TechConnectify No, you’re not missing anything except for the fact that very few people look at a 1200 square foot home and think, “How can I reduce the usable size?”

@transcendentape OK, if we're there then, this is all buttoned up.

To be clear, I'm not saying people should sacrifice floor space and get the air handler out of the attic. If they want to maximize both energy efficiency and usable space, I would probably push towards a mini-split setup.

But what I /am/ saying is... next time you build a home, add another 50 sq feet for the air handler closet. That's only been in my head 'til now, but that's where I've been from the start.

@TechConnectify Absolutely no arguments from me… except that if you’re building a new home in my climate, you should consider eliminating the attic as a non-conditioned space, regardless of where your HVAC is.

@transcendentape Agreed. I would, however, be curious to know whether there have been comparisons between a conventional attic with R-50 or maybe even R-75 insulation above the ceiling and a home where the attic has been eliminated or otherwise mildly conditioned.

But at this point, that's just academic!

@TechConnectify You’re essentially requiring a second structure to be built around the structure simply to hold the insulation. What in the world do yo propose to use as a regular building material with R50?

@TechConnectify And, more importantly, why?

Solar, wind, and hopefully storage and distribution will catch up soon. Advocating for R50 is not just unrealistic but possibly counter-productive in almost all situations.

@transcendentape Just in case I've misled you, I just mean above the ceiling to the attic. We don't go to that extreme for walls.

This isn't exactly a code reference but this is what we do here

https://insulationinstitute.org/wp-content/uploads/2015/12/IL-2012.pdf

@transcendentape And like, if this surprises you... that's kind of my whole point!

When I said we insulate the living space from the attic, I /meant/ it. Works just as well when it's -10 up there at night as it does on a hot summer day at 150 degrees.

@TechConnectify water vapor is what you I think you aren’t considering, but I accept your point.

@transcendentape Eh, I still feel as though with enough breathing (which, again, we absolutely ensure with roof and soffit vents) it's not a concern. The structure is only cooler than ambient for a few hours in the morning before it starts baking, and then when it's cooling off it's all really hot and water won't condense on it.

Breathing is critical, though, and I'll accept it may not be enough where you live with consistent grossness.

@TechConnectify I feel like we’re now arguing about finer points that I am not at all qualified to argue about.

@transcendentape Honestly, same. But I can attest that mold problems in attics are not at all common here.

It's usually either signs of a roof leak or as I said earlier the home was built when we thought "sure, just blow steamy shower air into the attic, it'll be fiiiine"

@TechConnectify I can attest that you and I are not in the same climate and I don’t understand why you continue to make this point.

When I started this conversation, I said, “You're not wrong, you're just advocating the wrong solution. Conditioned attic spaces with insulation under the roof deck is the best approach for slab on grade new construction with high solar loads and AC demands.” I stand by that claim.

@TechConnectify I’m not particularly interested in arguing the point further, as I doubt both of our qualifications.

@transcendentape Oh, sorry, I wasn't trying to be argumentative. I was just reinforcing my observation that we don't seem to have moldy attic problems.

Now, my gut tells me that a conventional Midwestern attic with an HVAC system inside of it would indeed be prone to moisture issues due to the fact that leakage from the ducts and/or cold surfaces of the equipment would encourage condensation. So, imo, removing the equipment would solve the problem.

But I have no proof beyond my gut

@transcendentape So by no means can I assert the same would be true where you live. I don't know the specifics of what causes moisture in attics for you.

Was just giving food for thought

@TechConnectify You’re hung up on insulation, while I’m trying to tell you that the existence of the unconditioned attic is the problem. Do you think no one in the south has considered insulation?

As you tighten up the building envelope, which is a requirement for efficiency, you exacerbate humidity problems that were previously dealt with by expected losses. Your gut feeling is simply not at all appropriate in my climate.

@TechConnectify From the most basic level, observe where vapor membranes are applied in your climate versus where they are in my climate.

@TechConnectify Now, given the fact that if I am not actively venting my attic, then I can expect it to be at least 50F higher than my conditioned space for maybe five months out of the year. 24/7. That’s not equivalent to outside temperature. And blown in insulation doesn’t have the vapor barrier on the correct side.

There’s a reason different climates have different building norms.

@TechConnectify Actively vent the attic? Why? When nightime temps are above 85F for three months what does actively venting the attic prove? The problem for me, in my climate, is the attic.

@TechConnectify We used to deal with this problem by having twelve foot ceilings and double hung windows and leaky construction with no A/C. Now that we are striving towards efficiency, the attic is the problem, and there’s a good history of home construction to show that attic insulation alone isn’t the solution.

I understand you also have hot days. I’m not talking about hot days. I’m talking about the fact that the lows do not drop below desired temps for months on end.

@TechConnectify Putting the mechanicals in the attic is silly in my eye, but it saves a bit of space in new builds. Putting the ducting in the attic simply makes sense when compared to whatever it is you are advocating. If it is your argument that the ductwork should be in the conditioned space, I agree. There’s a clear advantage to bringing the attic into the conditioned space that exceeds the idiocy of having ductwork inside the living space in my climate.

@transcendentape I feel like you missed some replies in the order I sent them - you seemed surprised by R-49 being code, or at least I pieced that together when I floated R-50 ceiling insulation and you said nobody would do that (or similar).

Regardless, I will grant you that I don't know the fundamentals of combatting moisture well enough to speak intelligently on the subject. However, I still question which approach makes more sense:

@transcendentape Make the attic part of the conditioned envelope, or create a moisture barrier between it and the living space then leave all mechanicals out of it.

Assuming a vapor barrier could be added to the R-50 ceiling insulation that's code here now, then why bother conditioning the attic at all? That's really the crux of my bafflement, and the normality of putting mechanicals up there where you live may cause the less effective thing to be standard due to legacy factors.

@transcendentape But, I will clarify what I mean by actively vent the attic:

In general, we don't prevent outside air from entering the attic. Quite the opposite, actually - we encourage it. Soffit vents below the eaves and roof venting help to rapidly equalize the attic temp with the outside temp once the sun sets.

Some homes also have mechanical ventilation in the form of an exhaust fan in the roof that switches on when it's above ~120 up there. The idea is to fight solar heating.

@transcendentape But that fan will shut off by nightfall.

Now, hopefully we agree that moisture will only condense (or at least problematically so) on things that are colder than ambient air. If mold weren't an issue prior to air conditioning becoming commonplace, that reinforces that notion.

So the real challenge is how to most cost-effectively prevent that both in terms of construction costs and ongoing energy costs. And here's the rub as I see it:

@transcendentape Putting the air handler and ductwork up there will obviously promote condensation more than if it weren't up there in the first place.

So, to what extent are the differences between construction techniques to mitigate that?

I can't answer that question - I can only guess. But it's really what I'm trying to pick apart because it seems like quite the confounding variable.

@TechConnectify There’s no reason for the air handler to be in the attic except for space saving and perhaps noise issues(?). That wasn’t common even 20 years ago. Ductwork is in the attic because there’s no other place for it to be if you are slab on grade. You can make the case that you should still have a crawl space even if you don’t need a basement to get below frost heaving, but for whatever reason, that’s just not a thing here anymore. I’m not sure why.

@TechConnectify So basically, if you don’t include stupid foot wide traces throughout the ceiling, the ducts go in the attic. Also, I need to remind you that the moisture problem isn’t simply the fact that the A/C infrastructure is in the attic. The moisture problem is because the attic is ventilated, and that’s precisely why eliminating the conventional attic is such a good idea in my area.

@transcendentape I know the moisture issue would persist even without the equipment up there, but surely it would be minimized, no? The ducts and equipment itself become much colder than ambient temps *inside* the home.

So that's really what I'm trying to ask - how much more effort are you spending to combat moisture merely because of that practice?

And the fact that you described the solution to slab-on-grade without resorting to ducts in the attic as stupid tells me a lot about sticky norms

@TechConnectify I keep my house at around 75F and about 35 relative humidity throughout the nine months of the year or so I am using A/C. During at least half of the year, both the outside temp and humidity exceed that. Simply venting the attic makes as much sense as opening up a window.

@TechConnectify Including the attic into the conditioned space allows me handle air exchange on my terms rather than through ceiling fixtures and cracks in the wall. It allows me to control humidity the same way I do in the walls. It allows me to achieve air handling efficiency rather than counting on drywall to be an air barrier.

@TechConnectify If you think OSB is a vapor barrier, then it’s clear I’ve wasted my time and I’ll bow out until you do the very minimum to educate yourself.

@transcendentape It's listed as an impermeable vapor barrier here:
https://en.wikipedia.org/wiki/Vapor_barrier
And like... I don't see why it wouldn't be! You could use mastic to seal it against the joists if you want to be extra-careful.

But, I'm willing to be wrong.

@TechConnectify I’m not interested in arguing with you any longer. I’ve never seen your house, but I know for a fact that your attic is not sealed with OSB and I think if you gave it half a second to think about why it wouldn’t work, instead of posting a wikipedia article that shows a wall, you would be able to understand why.

You do you, I’m done. Contact home builders or do better google-fu.

@transcendentape I will gladly be done!

I'll just say this - you wanted to know how to prevent moisture from forming on the backside of the colder ceiling drywall. At least, I think that's what you were asking.

Doesn't seem like rocket surgery to me to add an air and vapor barrier above the foot of cellulose insulation on top.

I really think we're talking in circles because how we imagine attics to function is too different.

@TechConnectify Get your ass up into your attic and place a vapor barrier above your blown in insulation with OSB. And when you’re done with that, come on down to Texas and fix all of our other problems as well.

@TechConnectify Maybe I could have made it more obvious, but despite the fact that you clearly don’t have any fucking clue what you’re talking about, it’s easy to insulate a wall. If you insulate the roof deck, it’s almost the same. When you insulate the ceiling, fuck off with your vapor barrier with conventional home building.

@TechConnectify But of course you wouldn’t be expected to know why that’s a problem. You’ve just spent two fucking days arguing it isn’t while I’ve been trying to explain to you why it is. So please, do your homework. I’m done.

@transcendentape Alrighty, I can't help it - you said earlier that it was the act of adding air conditioning that led to mold problems. Is that correct?

It's not simply that the attic is /there/ it's that there is now a place being maintained colder than ambient temperatures near to it.

Now, as far I as can tell, homes here are built like highly-insulated boxes. That box than gets a roof plopped on top of it.

I truly don't know what you mean by "it's easier to insulate a wall"