When builders began to insulate houses in the 1920s and 1930s, the exterior paint began to peel. Many painters concluded that insulation draws moisture and refused to paint a house if it was insulated. By 1938, the problem was common enough that Architectural Record published an article titled “Preventing Condensation in Insulated Structures.” The author, an architect named Tyler Stewart Rogers, argued that insulation was not the problem; indoor humidity was. He proposed a two-part solution: vapor barriers and attic ventilation.

Unfortunately, Rogers jumped to prescriptive solutions without fully understanding the problem, says Bill Rose, research architect at the University of Illinois and one of our country’s most respected building scientists. Rogers didn’t account for the effects of temperature on wood siding, and he didn’t address rain leaking in, which Rose says is “the greatest source of water in building envelopes.”

Vapor barriers and attic ventilation did not stop exterior paint from peeling, much to the delight of generations of asbestos-, aluminum-, and vinyl-siding salesmen. Nonetheless, within five years of Rogers’s article being published, his recommendations had been written into our earliest building codes, and the fledgling discipline of residential building science was off to its rocky start.

Seventy years later, our houses are bigger, more complicated, more airtight, insulated to higher levels, and dependent on ever-pricier fossil-fuel energy. Hence, the stakes of building science—comfort, health, durability, and energy bills—are higher than ever. Despite that, most architects, builders, and code officials still don’t understand moisture movement through houses. To make matters worse, there’s no easy way for them to learn about it.

Building science followed advances in comfort
Our efforts to make homes more comfortable—indoor plumbing, thermal insulation, central heating—and the problems resulting from those efforts gave rise to the first generation of building scientists, though they mostly called themselves engineers.

After World War II, man-made building materials such as plywood and dual-pane windows tightened up our houses, making them less drafty and more comfortable. But the air leaks that existed in houses were not all bad. For one thing, warm air leaking into walls and roofs helped to dry any moisture that was already there, whether from water pipes, humidity, or bad flashing. Perhaps more important, those random air leaks also were ventilating our houses. Fresh air entered houses through leaks (infiltration) around foundations and floors, while stale air exited through holes (exfiltration) in walls and roofs.

Despite those changes, our houses continued to perform reasonably well through the 1960s. We didn’t have major problems with rot or mold. And then in the 1970s, the energy crisis hit.

Building science moves to the forefront
When the cost of heating our homes skyrocketed, so did our motivation to heat them more efficiently. We began to experiment—passive solar, active solar, superinsulation, double walls, Larson trusses, envelope houses—which meant that we had to ask what works, what doesn’t, and why. As a result, scientists became interested in houses.

In 1977, an engineer at Princeton University named Gautam Dutt was crawling through attics to figure out why real houses were losing three to seven times more heat than his models predicted. According to Martin Holladay of Green Building Advisor, his eureka moment occurred when he pulled back some insulation and found a huge air leak through an unsealed utility chase. Dutt is credited with discovering the thermal bypass, which led to the realization that hidden air leaks were a far more serious problem than the obvious ones around windows and doors that had been the focus until then. From that point on, sealing hidden air leaks became a priority in the quest for energy efficiency and lower utility bills. Within a few years, the first blower doors were being sold commercially and used to find air leaks and to test homes for airtightness.

We also had our first catastrophic failures in the 1970s, as some  supertight houses became uninhabitable within a year due to mold and rot. Those failures helped us to realize that while tight houses save  energy, they also need ventilation. Also during the 1970s, the U.S.  Department of Energy was established, and scientists at atomic research  labs such as Oak Ridge in Tennessee and Lawrence Berkeley in California  began to study houses. Residential building science in the United States was ready to emerge as a serious, formal discipline.

It didn’t happen, though. In the mid-1980s, oil prices dropped, interest in energy efficiency waned, research funding was cut, and residential  building science lost critical momentum, at least in the United States.  In Canada and many European countries, including Germany and Sweden,  interest in building science (Europeans call it building physics) continued unabated, spurred on largely by government funding. In 1983,  for instance, the U.S. home-building industry was 20 times bigger than  Sweden’s, but the Swedish Council for Building Research spent more than  three times more on building research than the U.S. Department of  Housing and Urban Development. That same year, the National Research  Council Canada published Canada’s first textbook on building science, Building Science for a Cold Climate, by Neil B. Hutcheon and Gustav O.P. Handegord. Nearly 30 years later, an American equivalent still hasn’t been published.

Mold, asthma, and construction defects on the rise
Today, we are on the threshold of another major push for increased airtightness and more insulation in houses. Whether it’s the 2012 International Energy Conservation Code (IECC), Energy Star 3.0, Passive House certification, net-zero houses, or simply the movement to improve the efficiency of existing homes, the result is the same— tighter homes—and it has some experts worried.

Rose Grant is a research architect in the Building Technology Research Unit for State Farm Insurance and a former colleague of Bill Rose’s at the University of Illinois. “I think we are on the cusp of some serious building-science issues,” Grant says, “and mold is the canary in the coal mine.” In 2001, mold claims on homeowners’ policies cost insurance companies $1.3 billion, five times more than in the previous year. In 2002, they more than doubled again, exceeding $3 billion. It’s hard to say what happened after 2002 because most insurance companies began excluding mold from coverage.

In the past, experts argued about whether mold posed a serious health threat, but according to a 2007 study funded by the EPA, “Of the 21.8 million people reported to have asthma in the U.S., approximately 4.6 million cases are estimated to be attributable to dampness and mold exposure in the home.” The same study goes on to say, “The national annual cost of asthma that is attributable to dampness and mold exposure in the home is estimated to be $3.5 billion.” Those are just health costs; they don’t include mold remediation. The authors also estimate that dampness or mold is present in 47% of homes.

Dampness and mold could be signs of a maintenance problem. But a Feb. 10, 2011, article from Bloomberg BusinessWeek reports a doubling of construction defects per housing unit from 2000 through 2005 compared with the previous six years. The article references a 2007 University of Florida study in which 69% of the 17,000 defect claims reviewed were found to be associated with moisture penetration.

You could argue that bad flashing or failure to overlap building paper correctly results from poor workmanship, not a failure to understand building science, but the distinction may not matter. As we move toward higher-performance houses, not only do we have to get the weather-resistive barrier right, but we also have to bring a high level of craftsmanship to it. To do that, everybody involved in construction—frame carpenters, plumbers, electricians, HVAC installers, insulators, roofers, siding crews—needs an understanding of basic building science that just doesn’t exist on most job sites today.

You could argue that bad flashing or failure to overlap building paper correctly results from poor workmanship, not a failure to understand building science, but the distinction may not matter. As we move toward higher-performance houses, not only do we have to get the weather-resistive barrier right, but we also have to bring a high level of craftsmanship to it. To do that, everybody involved in construction—frame carpenters, plumbers, electricians, HVAC installers, insulators, roofers, siding crews—needs an understanding of basic building science that just doesn’t exist on most job sites today.

The cost of ignorance
To stay comfortable and to reduce energy costs, we’re adding more and more insulation to our homes and sealing air leaks with a vengeance. Without a thorough understanding of building science, though, you easily can trap moisture in walls and roofs, which can lead to peeling paint, mold, rot, and asthma. Ignore air leaks and you’ll pay a stiff energy penalty year after year.

Building science is not well defined
Building science is still an immature discipline, and its scope is not well defined. The narrowest definition focuses on heat, air, and moisture transfer in the building enclosure because that’s where most of the problems are. The broader definition also includes lighting and daylighting, acoustics, fire prevention, and structure.

Regardless of the definition, one of the mostimportant things that building science brings to residential construction is an emphasis on the house as a system. As houses have become increasingly complicated over the years, so too has the network of specialty trades among which we divvy up construction responsibilities. This division of labor makes it difficult for any one person to monitor how everything works (or doesn’t work) together. For example, an electrician installs the bathroom vent fan, a carpenter cuts in the dryer vent, a kitchen specialist hangs the range hood, an HVAC contractor puts in the furnace, a plumber installs the gas water heater, and a mason builds the chimney. Who’s in charge of the home’s ventilation?

Good building science not only requires that all the parts and pieces of a house work together, but it also demands that they be figured out ahead of time. The person doing the figuring matters less. It can be the architect, the builder, an energy specialist, or even a bona-fide building scientist, assuming you can find one.

Although the terms building science and building scientist are not well defined, they are certainly well used. Joseph Lstiburek, a founder of Building Science Corp. (BSC), an architecture and consulting firm near Boston, is perhaps the person in this country most qualified to call himself a building scientist, but he’s so frustrated by all the people misusing the term that he now refers to himself as an engineer.

For John Straube, a partner of Lstiburek’s at BSC, the dividing line between a person with a basic understanding of building and an actual building scientist is the ability to predict performance before it happens and to explain performance quantitatively afterward. “I would ask that a building scientist be able to calculate or predict things—R-values, heat loss, dew point,” Straube says.

Unfortunately, it’s not easy to become a building scientist. Auburn, Penn State, and the University of Minnesota, among others, all have programs in building science. MIT, USC, and UC Berkeley offer master’s degrees in building science. But, says Lstiburek in his typically candid way, “That’s total crap. They have no connection to real building science.” Eric Burnett, who taught building science for 20 years in Canada, was frustrated during the 10 years he spent trying to establish the program at Penn State. “One of the problems is the failure of current architectural and civil-engineering faculty to embrace the teaching of building science,” Burnett says. “They have other priorities.”

There are people working on the problem, however. The National Institute of Building Sciences has a committee devoted to enhancing education across the United States in building science and technology. Paul Totten, a practicing engineer in Washington D.C., is chairman of that committee. He says, “We’re way behind Canada and almost every European country.” One of the committee’s goals over the next five to ten years is to have “full-scale building-science master’s and Ph.D. programs with some consistency in what’s being taught. Right now, heat, air, and moisture transfer aren’t emphasized enough.”

But even a degree is just the beginning. Straube says, “There’s no way to prove that windows leak based on physics. The way we know windows leak is by experience. It’s dangerous when people learn the physics and don’t have the experience.” If we’re expecting hordes of young building scientists to come pouring out of universities and help us to fix all our houses, we’re going to have to wait awhile.

Architects should be trained in building science
Because the goal of building science is to predict how a house will perform, it makes sense that architects and designers should understand it, but building science isn’t emphasized in most architecture schools. Katrin Klingenberg, a German architect now living in Illinois and the head of the Passive House Institute US, says that when she looked into the level of science training for architects in this country, “I was flat-out shocked.” In Germany, she says, architecture students had to take six courses of building science over two years, with exams. If you didn’t pass the exams in three tries, “you had to go and find yourself a different job.”

Many U.S. architects today are becoming certified Passive House consultants because the nine-day training program includes so much building science. “We’re basically re-educating a whole generation of architects,” Klingenberg says. In fact, Carnegie Mellon University and the University of Oregon are looking to partner with the Passive House Institute US and incorporate parts of its certification program into their curricula.

Rachel Wagner is one architect who has taken the Passive House consultant training. She describes the teaching of building science in architecture schools as “woefully inadequate.” Wagner thinks that part of the solution is to make building science a section of the Architect Registration Examination. “Unless getting your license, your accreditation, depends on it, it’s not going to stick. It’s not going to be taken seriously,” Wagner says.

Despite the fact that architects are involved in few residential projects (maybe 5%), Lstiburek thinks the key to improving knowledge of building science is to fix architectural education. “Architects divorced themselves from the technology of construction,” he says. “If they were doing their jobs, I’d be out of business.” He believes that if you start with the architects, the rest of the industry will follow.

Is builder licensing the answer?
Producing more building scientists and educating architects in building science, however important, will not change the way houses are built. To do that, builders need to be educated. Pat Huelman, director of the Cold Climate Housing Program at the University of Minnesota, says, “We could have the best design, the best specs, we could have the right mousetrap, but if the person building it doesn’t understand what it’s supposed to do, it may not work when you’re done.” Paul Totten agrees. “The folks actually building the buildings need to be very deep in this subject,” he says. “Just making some minor errors in the field may cost you all of the performance that you should have gotten out of the building.”

At least some people in Oregon think the answer is builder licensing with a continuing-education requirement that includes building science. Legislation to that effect passed in 2009 and began to phase in last fall. When asked what prompted the legislation, Jon Chandler, CEO of the Oregon Home Builders Association, says that during the legislative session in 2007, “builders got pummeled in the press over construction defects—mold claims, water-intrusion claims, and so on. There was a solid week of front-page, above-the-fold articles. That was the tipping point.”

Not everyone agrees that contractor licensing and continuing education are the answer. Back in the 1990s, Minnesota had a requirement similar to Oregon’s, and Huelman was one of the people who taught the building-science courses. “I started to lose a little faith,” Huelman says, “because the owner of the company, or some delegate, was going to the class and learning about building science or energy, but that wasn’t traveling down to the guy who was putting in the window or to the siding contractor who was messing up the housewrap.”

Mark LaLiberte, who helped to set up the training programs in both states, hesitates to recommend any solution that will burden builders with more regulation, but he does advocate continuing education, especially to address building-science issues. “It’s the only solution that will bring builders to the point where they say, ‘I’m going to do this because it’s my reputation, it’s my business, and I’m a professional.’” He wants builders to seek that education on their own.

One thing everybody agrees on is that building science, just like the devil, is in the details. That’s why Straube says, “If I had to pick anybody to give training to, it would always be the site supervisor first.” Here and there, in fits and starts, some builders are getting trained, at conferences and online, through green-building certification programs, through Energy Star and Building America, but no single program is comprehensive or sufficient. The quality of the education offered varies considerably, and hucksters have set up shop to exploit this critical need. Even the most conscientious builders have a hard time learning what they need to know about building science.

How water gets into houses After rain and plumbing leaks, airborne moisture is the biggest source of water in walls and roofs, which is why sealing air leaks—creating an air barrier—is so important. The difference between (and relative importance of) air barriers and vapor retarders is probably the most widely misunderstood concept in high-performance home building.

Performance-based codes would help
“Code development isn’t predicated on good building science,” Huelman says. “It’s a political negotiation.” He explains that it often takes several years for a building failure to show itself. Then it takes several years to develop the language in the code that leads to a fix for the problem. It then takes several more years before the code is adopted, and another several years before the code officials are sufficiently trained. “You’re 10 to 15 years behind the eight ball,” Huelman says.

Given the complexity of the code-changing process, Totten worries about another risk. He points out, for example, that when you change code requirements for the airtightness of homes, you also have to change the codes for ventilation rates. “If we have a lag on one, particularly the ventilation rate, we’re going to create a whole pool of new problems.”

Perhaps the biggest issue with codes from the standpoint of building science is that they are prescriptive. They suggest that if you vent the crawlspace or if you install insulation with the correct R-value, you won’t have a moisture problem. However, success depends on how well you install the insulation and on how well you seal the air barrier, which is why Sweden, for example, has gone to performance-based energy codes. Like the Passive House standard, Sweden’s energy codes limit total energy use per square meter and specify an air-change rate. Meeting these requirements puts considerable pressure on builders to understand the science and to get the details right.

Whatever happens with our codes, our building inspectors need to understand building science thoroughly. They are the ones assessing the quality of the energy details before they’re covered up. Inspectors also have the authority to allow substitutions for code requirements, which can be dangerous without a deep understanding of building science. But it is no easier, and no more likely, for inspectors to educate themselves than it is for builders.

Let’s admit that it’s complicated
At some point in the past 30 years, without fanfare and without most of us ever acknowledging it, our houses crossed a threshold of complexity. They became dynamic systems whose construction and performance goes beyond the abilities and understanding of many of us in the industry. Most architects, builders, and code officials still can’t explain the difference between a vapor retarder and an air barrier. It’s not that we’re stupid. We know plenty of other things, but we haven’t had to know about building science. Now we do.

Creating homes that are comfortable, healthful, durable, and efficient means learning to build airtight, highly insulated houses. We can’t keep complaining that it’s too expensive. We can’t keep saying, “Houses need to breathe,” and then use that as an excuse to be careless about how we put them together. And we can’t be lazy and rely on prescriptive solutions. Those of us who build houses really need to understand the science of how they work. We have to take responsibility for educating ourselves.

by Kevin Ireton
From Fine Homebuilding 227, pp. 76-81 April 26, 2012

Learn what the difference is between latex, oil-based and shellac-based primers and how to choose the right one for the job.

For most paint jobs, both inside and outside the house, latex paint is preferred. Latex emits fewer odors and VOCs than oil-based paint, and it cleans up much more easily. In one area, however, oil-based products still hold their own over latex: primers. With interior applications and exterior spot-priming, there’s another option: shellac-based primers. All three primers can be used under latex topcoats. Choose a primer based on the condition of the substrate to be primed and its location. Before you open the can, though, be sure to prep the surface you’ll be priming. No primer will perform its best if the surface hasn’t been thoroughly scraped, sanded, or otherwise readied for painting.

Latex

Latex primers bond well with new wood or with old wood that has been sanded and is in good condition. They remain flexible after drying, which allows them to move with exterior wood during expansion and contraction. Latex primers are formulated to leave a smooth film on a smooth surface. However, that film won’t develop properly if the temperature is below 50°F or above 90°F. Latex primers don’t perform as well on weathered or damaged wood. They also don’t block knots or the tannins in cedar and redwood, and they raise wood grain more than oil-based or shellac-based primers. Cleanup is with water.
Cost per gallon: $14 to $23

Oil-Based

Oil-based primers are better than latex primers at sealing nail heads, covering knots in bare wood, and blocking tannin bleeding and other stains. They are also better for sealing bare window muntins that will be covered with oil-based window putty. Oil-based primers penetrate wood more thoroughly than latex primers, making them better at preparing weathered wood for paint. The best penetration is achieved by a slow-drying primer, but the trade-off is a longer wait before topcoating. When speed is more important than degree of penetration, oil-based primers that can be topcoated in one to two hours are available. Oil-based primers continue to harden as they age, which can be a problem with exterior applications. As the wood underneath expands and contracts, the primer remains rigid, weakening the bond with the wood and with the topcoat. Cleanup is with mineral spirits.
Cost per gallons: $17 to $23

Shellac-Based

Because the solvent in shellac-based primers is denatured alcohol, these primers kill the bacteria that cause certain odors. They are also great at covering knots and heavy stains. “If we have a problem stain from a knot bleeding through or a water stain that oil-based primer will not stop, then we turn to shellac-based primer,” says painter Philip Hansell. Because shellac softens in high temperatures, its use on exterior surfaces is limited to spot-priming. On the other end of the thermometer, shellac-based products are the only primers that can be applied in freezing temperatures. They don’t penetrate wood deeply, but are the fastest-drying primers available; a topcoat usually can be applied after 45 minutes. Cleanup is with denatured alcohol or ammoniated detergent.
Cost per gallon: $40 to $65

by Don Burgard
From Fine Homebuilding 226, pp. 34 March 8, 2012

Floors that are exposed on the underside to outdoor temperatures are often poorly insulated. Such floors can be found in homes with post foundations, in rooms over garages, and in cantilevered bays.

In many cases, these floors are casually insulated with fiberglass batts and covered with OSB or plywood. If the batts aren’t thick enough to fill the joist bays, they may fall away from the subfloor and rest on the OSB below. At that point, the floor assembly has an R-value of 0.

This type of floor usually leaks a lot of air, and the floor feels cold all winter long. If the floor includes plumbing, frozen pipes are a distinct possibility.

Bonus-room floors

There are two important reasons to do a careful job of air-sealing the floor of a bonus room over a garage: to improve the home’s energy performance and to prevent carbon monoxide from entering the room. Even after air-sealing, it’s essential that you install a CO detector.

When insulating a bonus-room floor, you’ll usually be working from below. If the area of the heated bonus room above the garage is smaller than the area of the garage ceiling, you’ll need to install blocking between the joists to provide an air barrier where the floor insulation stops. Locate the blocking under the kneewalls.

Blocking can be made from 2x lumber or rigid foam. If it is being installed between I-joists or floor trusses, rigid foam will be easier to cut into odd shapes than lumber. Whether you use 2x or rigid foam, it’s important to seal the perimeter of each piece of blocking with caulk or canned spray foam.

If the floor is the same size as the garage, it’s essential to air-seal the rim-joist area carefully. If ceiling joists extend from the house into the garage, you need to install blocking between the joists to maintain the home’s air barrier. Once the blocking has been installed, seal air leaks at the blocking and the rim-joist area on all four sides of the garage.

Air-seal, and hold insulation tight to subfloors The first step in energy-smart floor assemblies is air-sealing, which is particularly important in garages, where carbon monoxide and other toxic chemicals can leak into the living space above. Another significant detail is to make sure the insulation is held tight to the bottom of the subfloor; gaps negate the R-value of the insulation.

Floor above a garage This detail shows a garage bonus-room floor framed with open-web floor trusses. To prevent air leaks, it’s important to install caulk at all of the indicated locations. Ideally, the floor assembly won’t include any ducts. If there’s no way to avoid installing ductwork in the floor, specify deep floor joists, such as trusses, that provide plenty of room under the ducts for insulation, and be sure to include a continuous layer of rigid foam under the joists.

Smaller room over a large garage It is important to maintain a continuous thermal boundary between conditioned and unconditioned spaces. The weak link in this situation is the kneewalls. Install blocking (either wood or rigid foam) under the kneewalls, and insulate the walls, floor, and ceiling as shown.

Insulate ducts and plumbing, and put them close to the floor
If HVAC ducts are routed through the floor assembly, the floor joists must be deep enough to install several inches of insulation under the ducts. A floor with ducts also should be insulated with a continuous layer of thick rigid foam under the floor joists. To keep plumbing pipes from freezing, install them as close to the subfloor as possible, without insulation between the pipes and the subfloor. It’s also a good idea to install a layer of sealed rigid foam directly under the pipe. The rigid foam should extend the full width of the joist bay.

Cantilevered floors

If you’re about to insulate a cantilevered floor, the first step is to install blocking between the joists. The blocking should be located above the bearing wall below. It’s better for the blocking to be on the interior side of the bearing wall rather than the exterior side. Seal each piece of blocking at the perimeter to prevent air leaks.

You can insulate cantilevered floors many ways; the illustration shows rigid foam at the top and bottom of the joist bays. At the top of the joist bays, insert narrow rectangles of rigid foam between each joist, and secure that foam to the subfloor with a compatible adhesive. Seal the perimeter of each piece of foam with caulk or canned foam.

Once the upper layer of foam is installed, the joist bays can be insulated with either fiberglass batts or with dense-packed cellulose insulation. Under the floor assembly, install a continuous piece of rigid foam mechanically fastened to the joists and in an airtight manner. Protect the foam with plywood or solid soffit material.

Cantilevered floor The blocking above the bearing wall helps to define the home’s air barrier, so each piece of blocking needs to be sealed at the perimeter with caulk or canned spray foam. As long as both layers of rigid foam are installed with attention to airtightness, this type of cantilevered floor performs well.

5 Tips for a Thermally Efficient Floor

1. Air-sealing is just as important as insulating; it’s especially crucial to seal the rim-joist area.

2. Fiberglass batts are the worst type of insulation for this application. Spray foam performs well because it adheres to the subfloor and stops air leaks.

3. If you’re insulating with fiberglass or cellulose, the insulation must completely fill the joist bays, and the top of the insulation should be in full contact with the subfloor above. If you’re building an Energy Star house, these principles are mandatory elements of the Thermal Bypass Checklist.

4. It’s always a good idea to install a continuous layer of rigid foam on the underside of the floor joists, especially if the joist bays are insulated with fiberglass batts or cellulose. Rigid foam stops thermal bridging through the floor joists and helps with air-sealing, especially if the perimeter of each piece of foam is sealed with caulk or high-quality tape. One of the best tapes for sealing the seams of rigid foam is 3M All Weather Flashing Tape 8067. The rigid foam should be protected by a layer of plywood, OSB, or drywall (for a garage ceiling).

5. Whatever type of insulation you install, the total R-value of the floor assembly must be no less than minimum code requirements. The 2009 International Residential Code calls for a minimum of R-13 floor insulation in climate zones 1-2, R-19 in zones 3-4 (except marine 4), and R-30 in marine 4 and zones 5-8.

by Martin Holladay
From Fine Homebuilding 226, pp. 86-87 March 8, 2012

Weatherization contractors often use a blower-door test to help pinpoint leaks in the building envelope. Once your house is depressurized, you can use your bare hands to feel for air infiltration. The most common places to find air entering basements are around windows and doors and between the concrete foundation and the mudsill. But some air-leakage paths may surprise you: Air can even seep through the crack at the perimeter of your basement slab or through a sump in the basement floor. Here are five places to check for air leaks in your basement and some advice on how best to seal them.

Foundation walls
Walls made of poured concrete or concrete blocks are usually fairly tight. However, if your basement walls have any obvious cracks, fill them with silicone caulk. If the walls are made of stone and mortar, don’t use canned spray foam or caulk to seal cracks. Instead, remove any loose material from these areas, and repair them with mortar and small stones.

Use caulk or canned spray foam to seal leaks near wall penetrations for your electrical service, water service, cable service, or natural-gas service. Your home also may have penetrations for a fuel-oil filler pipe, an oil-tank vent, or a clothes-dryer vent. If basement access is awkward, some cracks may be easier to seal from the exterior.

In a tight basement Atmospherically vented appliances—for example, water heaters, furnaces, or boilers attached to old fashioned brick or metal chimneys—depend on air leaking through cracks in your walls to supply combustion air. If your basement is very tight, atmospherically vented appliances could be starved for air, and exhaust gases may struggle to exit through the chimney. That’s why the best appliances for tight homes are sealed combustion appliances equipped with ducts that supply outdoor air directly to the burners.

Because flue gases sometimes include carbon monoxide, it’s always important to be sure that your combustion appliances have adequate combustion air and that your chimneys draw well. If you plan to seal cracks in your basement, arrange for a combustion-safety test of any atmospherically vented appliances once air-sealing work is complete. Contact your gas utility or a home performance contractor certified by RESNET or BPI for more information on combustion-safety testing.

Rim joists
Air can leak through the crack between the top of the foundation wall and the mudsill, the crack between the mudsill and the rim joist, and the crack between the rim joist and the subfloor. The best way to seal leaks in the rim-joist area is with a high-quality caulk.

Once these cracks are caulked, you may want to reduce air leaks further by installing a layer of closed-cell spray foam at the rim-joist area using a two-component spray-foam kit.

Although spray foam is effective, it is expensive and sometimes messy. If you would rather not use it, you can insulate rim joists with rectangles of 2-in.-thick rigid foam (polyisocyanurate or extruded polystyrene). Seal the perimeter of each foam rectangle with caulk or canned spray foam. Don’t use fiberglass batts; they do nothing to slow airflow.

Two ways to air-seal and insulate a rim joist Rim joists are a common source of air leakage in basements and are often left uninsulated. The first step toward an energy-smart rim joist is to caulk gaps between the foundation wall and the mudsill, the mudsill and the rim joist, and the rim joist and the subfloor. As seen in the details shown here, you then can use rigid foam or spray foam to add another layer of air-sealing and to insulate the area.

Rigid foam You can cut the pieces of rigid foam roughly and somewhat undersize because the perimeter of each rectangle should be sealed in place with canned spray foam. With the rim joist air-sealed and covered with rigid foam, you can now add cavity insulation like fiberglass batts or, better yet, a second layer of rigid foam.

Spray foam Extend spray foam from the top of the foundation wall to the underside of the subfloor above. In addition to sealing leaks, 2 in. of cured foam will insulate to R-13. Most building codes, including the International Residential Code, allow spray foam installed at rim joists to remain exposed—without protection from a thermal barrier like drywall—as long as the foam is no thicker than 3-1⁄4 in.

Windows and doors
If your basement has old single-pane windows, they may need new glazing compound and weatherstripping. If the windows are in bad shape, consider replacing them with new double-glazed units.

If you rarely open your basement windows, consider sealing them shut with screws and caulk, or even covering them with rigid foam. (Of course, this advice applies only to small basement windows, not to any egress windows in a basement bedroom.) Don’t forget to caulk between the window frame and the concrete.

Every bulkhead entry needs a tight, weatherstripped exterior door at the base of the stairs. Be sure to caulk or to foam the gap between the door jamb and the foundation. If the door is warped or difficult to weatherstrip, it’s time to replace it. Most lumberyards can order a custom insulated entry door to fit any size opening. If you’re framing the rough opening, use pressure-treated lumber, and seal the frame to the concrete with canned spray foam.

Basement floors
After a new foundation is backfilled, the fill often shrinks away from the foundation, leaving a gap next to the basement wall that allows outdoor air to reach the footings. That’s one way for outdoor air to enter a home through cracks in the basement floor or sump pit. Even if a home has no shrink-age gap, air can still reach the footings, especially in areas with porous soil.

If there’s a crack at the perimeter of your basement slab, clean the crack with compressed air or a vacuum cleaner, and then fill it with caulk. If you have a sump pit without a tight lid, replace it with a new airtight lid. Sumps that have airtight lids are available from Jackel.

Basement ceilings
Chases and chimneys that extend from the basement to the attic should certainly be capped at the top, but the bottom of these chases should be sealed as well. After all, once air gets into a chase, it can move sideways into joist bays and partition walls until it finds an exit crack. This belt-and-suspenders approach is the best way to prevent the stack effect from stealing your home’s heat.

Cover large ceiling holes with plywood, drywall, or rigid foam, and seal the edges with caulk, spray foam, or housewrap tape. While you’re at it, check for holes under first-floor bathtubs or showers. Plumbers typically cut out a big piece of the subfloor to accommodate drain lines and traps; these air pathways should be sealed.Radon is a colorless, odorless, naturally occurring gas that can seep through soil into your basement. High radon levels can damage human health. While most homes have relatively low radon levels, some have dangerously high levels.

Sealing cracks in your basement can affect radon levels in your home, either for better or worse, depending on several factors. If necessary, a radonremediation contractor can install plastic pipes under your basement slab to lower the radonto safe levels.

The best way to determine whether your home needs radon-remediation work is to test the air in your home. For more information on radon testing and remediation, visit epa.gov/radon.

For details on radon mitigation, see GreenBuildingAdvisor.com/radon.

by Martin Holladay
Drawings: Steve Baczek, Architect
From Fine Homebuilding 225, pp. 82-83 January 19, 2012

Amy Fenwick Frank
Division of Codes and Standards
PO Box 802
Trenton, NJ 08625-0802
Fax Number: (609) 633-6729
Email: *protected email*

Following are some of the proposed actions:

Adding a sentence to the current amendment to 210.8(A)(5). The current amendments reverts 210.8(A) (2) and (5) back to the National Electrical Code 2005 text. This proposed amendment will correlate with the existing amendment to 210.8(A)(2), which clarifies receptacles installed under the exceptions to 210.8(A)(5) do not meet the requirements of 210.52(G).”

Section 210.12(B) Branch Circuit Extensions or Modifications Dwelling Units will be deleted, because it is regulated by the Rehabilitation Subcode.

The current amendment to NEC 334.10(1), which permits the use of Type NM cable in accessory buildings or structures of dwellings will be deleted, because the text is now included in the 2011 NEC.

The amendment to 300.4(A)(1) will be retained. This amendment references the building subcode for the placement of cable- or raceway-type wiring methods installed through bored holes in joists, rafters, or other wood members.

The amendment to 334.12(A)(2) will be retained. This amendment deletes this item and permits exposed Type NM cable in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings.

The amendments to the support requirements in 342.30(C) Intermediate Metal Conduit, 344.30.(C) Rigid Metal Conduit, 352.30(C) Rigid Polyvinyl Chloride Conduit, 355.30(C) Metallic Tubing Reinforced Thermosetting Resin Conduit and 358.30(C) Electrical Metallic Tubing, will be deleted, because the 2011 deleted these requirements.

Section 406.4(D)(4), which requires arc-fault circuit-interrupter (AFCI) receptacles to be installed when receptacles are being replaced in a dwelling unit will be deleted, because additions, alterations and modifications are regulated by the Rehabilitation Subcode.

All current amendments to Chapter 5 Special Occupancies will be retained.

The amendment to 645.17, Power Distribution Units will be deleted, because the text is contained in the 2011NEC.

Section 680.42(B) will be deleted and replaced with the text from Tentative Interim Amendment (TIA) issued by the NFPA. This section addresses the bonding requirements for spas and hot tubs. The amendments will not require equipotential bonding of perimeter surfaces for listed self-contained spas or hot tubs that meet certain conditions.

The current amendment to 800.156 will be retained. This amendment deletes the requirement for a communications outlet in dwelling units.

“The new International Green Construction Code will help reduce energy use and greenhouse gases through mandatory green building design.”

Protecting the Environment
Unlike other building codes, which are intended to protect the public’s health, safety, and welfare; this complementary green code is intended to help reduce a building’s negative effect on the environment by setting minimum mandatory requirements. For example, in the code’s current version, mandatory requirements include energy performance that is 30-percent better than the 2006 International Energy Construction Code and fixture and flow fitting rates that are a 20-percent improvement over the 2006 International Plumbing Code.

It is important to note that the IGCC will not supersede or take precedent over established sustainability rating systems, such as the U.S. Green Building Council Leadership in Energy and Environmental Design (LEED®) and American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards. Rather, the new code will serve as an overlay to the existing International Building Codes and complement those existing standards or systems. The IGCC public comment version contains provisions for:

• Site development and land use
• Material resource conservation and efficiency
• Energy conservation and earth atmospheric quality
• Water resource conservation and efficiency
• Indoor environmental quality and comfort
• Commissioning, operation, and maintenance

Local Jurisdictions Determine Code Application
Both the IGCC and LEED rating program produce the same results and share similar categories, such as site, water, energy, materials, and indoor air quality. However, unlike LEED, which is voluntary and determined by the owner’s level of commitment, the IGCC is intended to be part of the building code enforced by those local jurisdictions that adopt it, integrating with existing international building codes to create a new regulatory baseline for green construction.

A key feature is a section devoted to “jurisdictional electives” that will allow customization of the code – beyond its baseline provisions – to address local priorities and conditions. For instance, if local area has water problems, then a jurisdiction may elect for more strict water conservation measures. Project electives within the IGCC will be determined by the jurisdiction and range from 0 to 14, depending on the level of sustainability the jurisdiction is trying to achieve.

Who will be affected?
The IGCC applies to all occupancies, but does distinguish that residential occupancies shall comply with ICC 700 National Green Building Standard and that equipment and systems primarily used for industrial or manufacturing processes shall not comply with the code. Other than those two exceptions, the IGCC applies to the design, construction, addition, alteration, change of occupancy, movement, enlargement, replacement, and repair of buildings and structures and the site on which the building is located. Like all other I-codes, the code official has the authority to render the interpretation of the code and to adopt any policies and provisions in order to clarify the code.

Schedule
The IGCC is scheduled for final publication in early 2012. Currently, public version 2.0 was released on November 3, 2010, with the following key milestones:

• Public version no. 2: November 2010
• IGCC Code change submittal deadline: January 2011
• IGCC Development hearing: May 2011
• IGCC Final action hearing: November 2011
• Final Release: Early 2012

Be Informed
The IGCC is part of the International Building Code family and is being supported and developed by:

• American Institute of Architects
• ASTM International
• American Society of Heating, Refrigerating and Air-Conditioning Engineers
• U.S. Green Building Council
• Illuminating Engineering Society

 Betzwood Associates completes a residential addition & renovation project in Gladwyne, PA.

Frank Mariani, Inc.

Joanne Bateman Interior Designs, LLC

Peter / Kubilus

A 1⁄8-in. crack doesn’t seem like much to worry about, but a 1⁄8-in. crack that runs the length of your house amounts to a square hole 8 in. on a side—a big-enough hole to toss a cat through. Because it is a crack, you can seal it with caulk, but not all holes in the building envelope are cracks that can be sealed with a tube of caulk. Some of them really are big enough to toss a cat through, and they need to be sealed with sheet goods such as drywall, rigid foam, or plywood.

Some common gaps and holes are listed in the Energy Star thermal-bypass checklist. Among the most common holes found in poorly sealed houses are holes near soffits, chases, and bathtubs. Green Building Advisor has a collection of 56 detail drawings that pertain to the Energy Star checklist. These drawings come from that collection.

Chases and soffits are raceways for air leaks
Older houses often have several big holes in the attic floor. Many are around open chases for ducts, electrical cables, or flues, often running unimpeded from the basement to the attic. When installing plumbing chases in new houses, install air-barrier sheathing first, and seal the gaps between intersecting walls with caulk. As the framing shrinks, these gaps become large. The top of an open plumbing chase in an existing house can be sealed with a variety of sheathing materials as long as seams and edges are sealed with caulk or tape.

If any chases for plumbing pipes, ducts, or flues originate in the basement, be sure to seal the chases at the bottom with the same techniques you used to seal the chases in the attic.

While you’re in the attic, check for any unsealed kitchen soffits. Such soffits are often built above a row of wall cabinets. In new construction, the ceiling drywall should be installed and taped before the soffit is framed. The first clue to a leaky soffit is often a piece of discolored fiberglass insulation. The discoloration is caused by escaping air that has carried dust upward, often for years.

In many existing houses, the sides and top of kitchen soffits are open to the framing cavities. In this case, you can install the neces-sary pieces of air-barrier sheathing from above. Don’t forget to seal the perimeter of the sheathing and any seams with durable tape, caulk, or spray foam. Once the soffit is airtight, don’t forget to replace the insulation.

Tubs hide big holes in floors and walls
 Tub installation When you’re installing a fiberglass tub/shower unit against an exterior wall, it’s essential to insulate and air-seal the wall before installing the tub. On new-construction jobs, remember to install a durable air-barrier material (for example, Thermo-ply sheathing) to cover the insulation.

In an existing house where builders omitted the insulation and the air barrier behind the tub, repairs are difficult. One solution (not the cheapest) is to remove some of the siding and sheathing so that spray-foam insulation can be installed from the outside. A better bang for the buck may be to address the problem as part of a larger bathroom remodel. If you’re contemplating a bathroom upgrade, it may be cheaper to demolish the tub/shower unit and seal the wall properly from the interior.

If your house has an unconditioned basement—in other words, if the basement ceiling is insulated—be sure to pull that insulation aside and check for air leaks under any first-floor bathtubs or showers. Plumbers typically cut out a big piece of the subfloor to accommodate drain lines and traps, but rarely repair the ruptured air barrier. If these cutouts are not sealed, your floor has a huge hole.

Keep fireplace heat inside
Prefab fireplace niche Prefabricated metal fireplaces, whether wood-burning or gasburning, are usually installed in a niche framed into an exterior wall. Unfortunately, many of these fireplace niches are poorly sealed against air leaks.

The best opportunity to prevent such leaks is before the fireplace is installed. After the niche is carefully insulated, the insulation should be covered with a durable, rigid air-barrier material, such as Thermo-ply sheathing, drywall, sheet metal, or OSB. All gaps and seams should be sealed with caulk, spray foam, or contractors’ tape. Where the chimney penetrates the niche ceiling, seal gaps with metal flashing and high-temperature silicone caulk.

To repair air-barrier defects behind an existing metal fireplace, it may be necessary to remove sections of siding and sheathing to provide access for the installation of spray polyurethane foam.

Fine Homebuilding222, pp. 90-91

Center Ice currently offers two NHL size rinks for everything from public skating and hockey to youth and adult leagues. In addition they also offer lessons for Learn to Skate and Learn to Play Hockey. Check them out at Oakscenterice.com.

Betwood Associates PC, along with their design partners N.E. Fisher & Associates and Engineering One PC, was hired to provide architectural and structural professional services to design a 25,000SF addition to the existing twin ice skating facility owned by C.D. Professional Sports, LP.  The new addition will offer a 3rd NHL size rink at the Oaks, PA facility. N.E. Fisher & Associates, Boyertown, PA is the Project Mechanical Engineer, and Engineering One PC, Phoenixville, PA is the Project Electrical Engineer. In addition to the NHL size rink, new Player and Referee Locker Rooms, a “Warm-up Room”, and mechanical space for the rink’s ice making equipment will be provided.

InLand Design, LLC of Exton, PA provided the civil and land development design engineering for the project, which will include improved access to and parking at the facility.

The General Contractor for the project is Dylan Enterprises of Boyertown, PA. Schlosser Steel Buildings, Inc. of Hatfield, PA is providing a Star Building Systems “pre-engineered” building to seamlessly match the exterior of the existing facility. The “cold slab”, ice making and rink equipment is being provided by B K Mechanicals, Inc. of West Chester.

The building design was recently completed, and is currently being reviewed by Upper Providence Township to issue a building permit to the Owner. C.D. Professional Sports, LP anticipates construction to start in the near future, with completion scheduled in the 3rd Quarter of this year.

Use of the new rink by area hockey teams and skaters is anticipated to begin by year’s end.