ASHRAE Journal - September 2009 - 72

Wood Furring Reflective Foil Vapor Barrier Trapping Water Inside Wall Assembly Paper-Faced Gypsum Board Stucco Wood Baseboard Stucco Rendering Extends Below Grade Acting As a Wick Tile Floor Concrete Slab Masonry Block Wall Baseboard Reflective Foil Insulation Gypsum Board Sub-Slab Vapor Barrier Perimeter Edge of Slab Not Protected Below Grade Ground Saturated With Water Concrete Grade Beam Concrete Slab Polyethylene Vapor Barrier Figure 1a: Maximizing Damage. Wicking water inward at perimeter while trapping water in the assembly with an interior reflective insulation foil-faced vapor barrier. Figure 1b: Rain Penetration. There are only two kinds of stucco: stucco that leaks and stucco that will leak. Notice that the reflective insulation foil-faced vapor barrier traps water in the wall. Mold in Alligator Alley By Joseph W. Lstiburek, Ph.D., P.Eng., Fellow ASHRAE pain gave Florida to the United States in exchange for the United States giving up any claims on Texas. We all know how that turned out. Nobody really wanted to live in Florida except the Seminoles until air conditioning was invented. It took a New York boy by the name of Willis Carrier to make the state habitable for the rest of us.* The good news was that air conditioning came to Florida. The bad news was that air conditioning came to Florida. With air conditioning came people. Also, with air conditioning came mold.† When you air condition, you make things cold. When things get cold, they sweat when it is humid. It gets humid in Florida. So let’s build air-conditioned boxes in Florida lined with paper. What could possibly go wrong? Well, it rains in Florida, and the state is pretty much a swamp. The air-conditioned, paper-lined box is rained on while sitting on wet ground. Occasionally, hurricanes and wildfires occur. This Florida box becomes wet from underneath, from the sides S and top and sometimes blows away. Thank goodness most of them are so wet they can’t burn. They just smolder. It’s easy to understand the physics of building on wet ground: build on top of it and prevent water from wicking into the building by capillarity. But, in Florida we seem to go out of our way to do it wrong. We use capillary active materials such as concrete, block and stucco and configure them in such a manner as to maximize damage (Figure 1a). We don’t wrap a sub-slab vapor barrier capillary break around the perimeter of the foundation, and we extend a stucco cladding into the ground to suck every last available drop of water in the ground into the structure. Then, we line the interior with a reflective insulation foil-faced vapor barrier reinforced with mold food (aka kraft paper).‡ But, we don’t stop doing things wrong. Rain falls on the sides of the structure (Figure 1b). So, we apply the stucco directly to concrete block and assume that the stucco (and the paint on the stucco) keeps the rain out. I call this “faith-based rain control.” The stucco leaks, the paint leaks, the block leaks, and the wall can’t dry to the interior because of the reflective insulation foil-faced vapor barrier. * Yes, I know that John Gorrie, a legendary Floridian, invented an ice-making machine to cool his hospital patients in Apalachicola, Fla., in the 1840s. However, the idea of what we consider modern air conditioning was never fully developed until Willis Carrier came along. † Everybody take a Valium. Yes, there was lots of mold in Florida buildings before the advent of air conditioning, but hyperbole is allowed in a column written by me. Think of air conditioning as the fertilizer that helped improve mold yield per acre of floor area. ‡ This radiant barrier insulation nonsense is getting out of hand. If you think that it provides any thermal benefit on the inside of the typical mass wall, I have some swampland in Florida that is for sale. 72 ASHRAE Journal ashrae.org September 2009

ASHRAE Journal - September 2009

Table of Contents for the Digital Edition of ASHRAE Journal - September 2009

ASHRAE Journal - September 2009
Contents
Commentary
Industry News
Letters
Meetings and Shows
Getting to Net Zero
Feature Articles
How High Can You Go? Building Height and Net Zero
Lab for Learning
Solar Hot-Water Heating System: Lessons Learned
50th Anniversary—Low Pressure Steam Heating Systems
Building Sciences
Products
Emerging Technologies
People
Classified Advertising
Advertisers Index
ASHRAE Journal - September 2009 - ASHRAE Journal - September 2009
ASHRAE Journal - September 2009 - Cover2
ASHRAE Journal - September 2009 - 1
ASHRAE Journal - September 2009 - 2
ASHRAE Journal - September 2009 - Contents
ASHRAE Journal - September 2009 - 4
ASHRAE Journal - September 2009 - Commentary
ASHRAE Journal - September 2009 - Industry News
ASHRAE Journal - September 2009 - 7
ASHRAE Journal - September 2009 - 8
ASHRAE Journal - September 2009 - 9
ASHRAE Journal - September 2009 - Letters
ASHRAE Journal - September 2009 - 11
ASHRAE Journal - September 2009 - 12
ASHRAE Journal - September 2009 - 13
ASHRAE Journal - September 2009 - 14
ASHRAE Journal - September 2009 - 15
ASHRAE Journal - September 2009 - Meetings and Shows
ASHRAE Journal - September 2009 - 17
ASHRAE Journal - September 2009 - Feature Articles
ASHRAE Journal - September 2009 - 19
ASHRAE Journal - September 2009 - 20
ASHRAE Journal - September 2009 - 21
ASHRAE Journal - September 2009 - 22
ASHRAE Journal - September 2009 - 23
ASHRAE Journal - September 2009 - 24
ASHRAE Journal - September 2009 - 25
ASHRAE Journal - September 2009 - How High Can You Go? Building Height and Net Zero
ASHRAE Journal - September 2009 - 27
ASHRAE Journal - September 2009 - 28
ASHRAE Journal - September 2009 - 29
ASHRAE Journal - September 2009 - 30
ASHRAE Journal - September 2009 - 31
ASHRAE Journal - September 2009 - 32
ASHRAE Journal - September 2009 - 32a
ASHRAE Journal - September 2009 - 32b
ASHRAE Journal - September 2009 - 33
ASHRAE Journal - September 2009 - 34
ASHRAE Journal - September 2009 - 35
ASHRAE Journal - September 2009 - 36
ASHRAE Journal - September 2009 - 37
ASHRAE Journal - September 2009 - Lab for Learning
ASHRAE Journal - September 2009 - 39
ASHRAE Journal - September 2009 - 40
ASHRAE Journal - September 2009 - 41
ASHRAE Journal - September 2009 - 42
ASHRAE Journal - September 2009 - 43
ASHRAE Journal - September 2009 - Solar Hot-Water Heating System: Lessons Learned
ASHRAE Journal - September 2009 - 45
ASHRAE Journal - September 2009 - 46
ASHRAE Journal - September 2009 - 47
ASHRAE Journal - September 2009 - 48
ASHRAE Journal - September 2009 - 49
ASHRAE Journal - September 2009 - 50
ASHRAE Journal - September 2009 - 51
ASHRAE Journal - September 2009 - 52
ASHRAE Journal - September 2009 - 53
ASHRAE Journal - September 2009 - 50th Anniversary—Low Pressure Steam Heating Systems
ASHRAE Journal - September 2009 - 55
ASHRAE Journal - September 2009 - 56
ASHRAE Journal - September 2009 - 57
ASHRAE Journal - September 2009 - 58
ASHRAE Journal - September 2009 - 59
ASHRAE Journal - September 2009 - 60
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ASHRAE Journal - September 2009 - 69
ASHRAE Journal - September 2009 - 70
ASHRAE Journal - September 2009 - 71
ASHRAE Journal - September 2009 - Building Sciences
ASHRAE Journal - September 2009 - 73
ASHRAE Journal - September 2009 - 74
ASHRAE Journal - September 2009 - 75
ASHRAE Journal - September 2009 - 76
ASHRAE Journal - September 2009 - 77
ASHRAE Journal - September 2009 - 78
ASHRAE Journal - September 2009 - 79
ASHRAE Journal - September 2009 - 80
ASHRAE Journal - September 2009 - 81
ASHRAE Journal - September 2009 - Products
ASHRAE Journal - September 2009 - 83
ASHRAE Journal - September 2009 - Emerging Technologies
ASHRAE Journal - September 2009 - 85
ASHRAE Journal - September 2009 - 86
ASHRAE Journal - September 2009 - 87
ASHRAE Journal - September 2009 - 88
ASHRAE Journal - September 2009 - 89
ASHRAE Journal - September 2009 - People
ASHRAE Journal - September 2009 - 91
ASHRAE Journal - September 2009 - 92
ASHRAE Journal - September 2009 - Classified Advertising
ASHRAE Journal - September 2009 - 94
ASHRAE Journal - September 2009 - 95
ASHRAE Journal - September 2009 - Advertisers Index
ASHRAE Journal - September 2009 - Cover3
ASHRAE Journal - September 2009 - Cover4
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