Dumb Things to Do in the South:

Joe Lstiburek Explains His "Top Ten List"

"... for those too cheap to come to one of my sessions."

	Nothing we have published in e design this year has raised more questions and challenges than Joe Lstiburek's "Top Ten List of Dumb Things to Do in the South."(e design print, November 1995). The response was quick. "Why?" builders demanded to know. "What's wrong with vented attics? What's he got against brick? What does vinyl wallpaper have to do with anything?"
	Lstiburek calls himself a "forensic engineer." He gets called in to "do the autopsy" when buildings die of bad indoor air quality (IAQ). But, he's also an IAQ doctor. When possible, he helps to"raise the dead." His "Top Ten List" is part of a hard-hitting, humorous presentation he made at FDI's Roundtable last year. Each item was fully explained in the presentation, but as one reader pointed out, it's a bit unfair to print such challenges to conventional wisdom without comment. Back we went to Lstiburek to see if we could squeeze some explanatory text out of him.
	With grace and sharp humor he sent us a detailed explanation of each point--with one caveat: "Don't edit an explanation. Print it the way it's written."
	So here is the fully-annotated, world premiere of Joe Lstiburek's "Top Ten List of Dumb Things to Do in the South" (explained for those too cheap to come to one of my sessions).
	10. Vented Attics and Vented Crawl Spaces My definition of an unvented attic is an attic where there are no vents and where the attic insulation follows the slope of the roof sheathing thereby including the attic space within the conditioned building envelope.
Myth Reality	The rationale for venting attics in the South is to "flush" heat. The dominant heat transfer mechanism in an attic is radiation. Venting attics will not "flush" radiation. The air change in a perfectly built and vented attic (code 1:300 ratio) results in an average air change rate of 3 to 6 ach(air changes per hour). At this rate there is approximately a 2 to 3 percent reduction in heat transfer to the conditioned space. This assumes an airtight ceiling and no ductwork in the attic and certainly not leaky ductwork in the attic. The moment leaky ductwork is installed in a vented attic there is approximately a 25 percent increase in heat transfer to the conditioned space. Of course, this does not happen if you have an airtight ceiling (then the penalty for venting the attic is only 5 to 7 percent. If you locate the ducts within the conditioned space and also build an airtight ceiling, this is approximately 2 to 3 percent more efficiency than my version of an unvented attic. Of course, when is the last time you saw ductwork below an attic ceiling coupled with an airtight attic ceiling? So much for the energy concerns. Now let's talk moisture. What? Are you all crazy? The air outside is hot, humid and disgusting. And you want to bring this into an attic where it can diffuse through vapor-barrierless attic insulation and get to the cold, air conditioned ceiling? Hell, before it gets there it will see those cold R-6 insulated ducts, fittings, etc. and drip all over. Give me a break. Venting attics in the South was dreamed up by some disgruntled Yankee p**s*d about the Civil War. Let's now talk durability of shingles and shingle temperature. Venting or non-venting a roof has about a 5 percent impact on shingle durability. The color of the shingle is more important than the venting or non-venting. And temperature is less important than the shingle getting a sunburn. The best roof for hot, humid climates is a concrete or clay tile roof. Period. Crawl spaces are real simple to understand and deal with. When you vent crawl spaces you bring in hot, humid air and cause moisture and mold problems. The ground surface is typically colder than the dew point temperature of the exterior air. The underside of crawl space floor insulation is radiation-coupled to the ground surface and is very close to the same temperature as the ground. Moisture droplets can be seen all over the top surface of typical polyethylene ground covers as well as hanging from the bottom surface of the crawl space floor insulation. Gee, I wonder how all the water got through the poly ground cover? It must have leaked through the walls. Give me another break. Now, when moisture is in the insulation where do you think it wants to go? Where is the air conditioning? Moisture moves to the cold surface. Venting crawl spaces made sense only when you had no air conditioning and no insulation and no crawl space walls.
	9. Buildings That Suck (ducts in attics, crawl spaces, etc.) This is a no brainer. Negative air pressures in buildings in hot, humid climates induce infiltration of hot, humid air. Period. Leaky ducts in vented attics and vented crawl spaces lead to negative air pressures.
"Bad Stuff"	8. Lined Ducts (ductboard or acoustical liner) You can never clean them. When they are wet and dirty and they grow bad stuff, the only thing you can do is throw them out. At least you can clean and decontaminate the metal ducts. You don't need lined ducts for acoustical reasons. The acoustical argument to justify lined ducts is only used by engineers and others who don't know how to design acoustically. Put the ducts inside, and you don't need to insulate them much, especially if you control the interior humidity. Of course, you need to know how to do that. When was the last time you saw an engineer figure out how to handle the latent load? I'll let you in on a little secret, you can't do it when you mix ventilation, you can't handle the latent load. The rule is always deliver neutral-temperature, dry ventilation air; and not worry about other moisture loads. If you keep the rain out, there won't be any. Now keeping the rain out may be a problem (see #5).
	7. Vinyl Wallpaper This is a vapor barrier on the wrong side of the wall. It should be put on the outside of buildings, not the inside, in the South.
	6. Carpets in Schools or on Slabs If a carpet is dry, at the same temperature as the occupied space, and cleaned, it is great. I like carpets that are dry, have no temperature gradient across them, and are cleaned. In schools which are slabs on grade, forget it. The carpet is regularly colder than the air, especially when the a/c is turned off and you get the thermal lag. Now you have a higher relative humidity in the carpet than in the air. Now you get mold and dust mites. When was the last time you saw a school with a decent housekeeping budget? They can't afford to pay the teachers! Of course there is always money to pay the 16 levels of administrators.
	5. Exterior Insulation and Finishing Systems (EIFS) These systems are a disaster when they are applied over metal studs and gypsum or wood sheathing. They don't work because they do not have a drainage plane. For those of you who remember the traditional stucco, the drainage plane was the building paper installed shingle-fashion over the exterior sheathing and under the metal lath. Traditional stucco always leaked rainwater. The function of the building paper was to drain this leaking rainwater to the exterior. Brick leaks; wood siding leaks; vinyl siding leaks; etc. That is why all of these exterior claddings have building paper behind them to drain this water back to the exterior. These types of systems are called "forgiving" or "water managed". Synthetic stucco systems typically do not have a drainage plane and, therefore, are a disaster.
	4. Brick I love brick. I also hate brick. Let me tell you when I hate it. I hate it when it does not have a drainage plane behind it that is also an extended vapor barrier. Wet brick exposed to the sun is like a moisture capacitor which discharges to the cold side. The cold side is the interior air-conditioned space. I love brick when there is a vapor barrier acting as a drainage plane between the brick and the rest of the wall assembly. Most brick in the South is installed without functioning drainage planes and effective vapor barriers. If you are not going to use it right, don't use it. When it is used right, it is the best exterior cladding system around (just don't paint it).
	3. Through-the-Wall AC/HP Units or Unit Ventilators Supplying Make-Up Air They can't handle part-load conditions. Most systems that use them are inherently designed to be negative pressure systems (meaning the building conditioned space operates at negative pressure). I like them when they only do cooling and supply no outside air.
	2. ASHRAE Standard 62 (20 cfm of outdoor air per person) Dilution is not the solution to indoor pollution in the South. A bunch of cowardly Yankees refused to target the real issue of source control in many buildings due to the related issue of material off-gassing. Too many manufacturers of building products would get pi**ed off: "What? You want me to actually tell you what I put in my product? And then tell me I can't put it in? No way! Hey, why don't we increase air change and flush out the nasties? Everyone wins! You get to sell more energy. You get to sell more and bigger equipment. Every existing system is now obsolete, and now you have to make it bigger. Engineers get to charge more. Contractors really win. And you can continue to put the bad s**t in the products and sell them." Of course, no true Southerners were in that meeting. In the South there is more bad s**t in the outside air than there is bad s**t in the inside air. It's the charm of the South.
	1. Northerners Coming South to Design Buildings Self explanatory. (But only if you get the full picture of what Lstiburek has seen and come to understand from dozens of sick buildings in the South. And he's not just talking about those "Yankees" that forced ASHRAE 62 down our throats. There's plenty of homegrown malpractice. The enemy is the whole range of thinking, products, standards, and practices that are fine in other climates, but poison buildings and people in Florida and the Gulf Coast South. Lstiburek's ironic humor really masks a sense of outrage at our ongoing refusal to heed the hard lessons of science in preventing sick buildings in hot, humid climates. Ed.)
	Jim Minter, Editor