Weighing the Merits of Spray Foam Insulation

first_imgEnergy codes aren’t everythingEnergy codes may call for R-49 in the roof, but that doesn’t mean it’s absolutely necessary, some commenters argue.Among them is A.J. Builder in upstate New York, who writes that “code R-values do not factor in how well spray foam works compared to fiberglass of the same R value. Most times spray foam is not installed to code R values and yet it performs much better than fiberglass.”Others go even further. Meeting the R-49 requirements is a “waste of money,” Eric Price writes.“Eric is right,” adds John Pfeiffer. “IMHO the law of diminishing returns really takes a bite out of using more than 2 to 3 in. of closed-cell (depending on your location, I’m in southern N.Y., zone 4a). Don’t trust the codes for telling you what is the most cost-effective way to insulate a house. They are written by people wearing suits and working in offices, not contractors.”An R-40 roof may leak half the amount of heat as an R-20 roof, he says, but savings may amount to only pennies per square foot at the expense of adding twice the amount of insulation at double the cost.“Also, consider what happens if your roof has a leak,” he adds. “Open-cell is a sponge and will need to be taken out and replaced; closed-cell won’t show the leak and will soak the plywood until something gives.” GREEN PRODUCT GUIDE Spray Foam Insulation: Open and Closed CellIt’s OK to Skimp On Insulation, Icynene Says Concerns When Using Spray Foam in RetrofitsGreen Basics: Rigid Foam Insulation PHIUS Says No to Some Types of Spray Foam Our expert’s opinionGBA technical director Peter Yost added this:Scott, it sure sounds as though you would like to optimize energy performance, taking advantage of the framing cavities being open, and do it as economically as possible, including DIY. Given all that, here are my recommendations:Get a sense of where to spend your money – the best two ways to do this, in my opinion, are to get a whole-house performance assessment done by a BPI-certified technician, and to use the LBNL Home Energy Saver Pro Energy Assessment Tool. I have used this on more than one project, and using the detailed assessment path, I have come within $100 of total household annual utility bills, and their recommendations are useful.Seriously consider the DIY rigid-foam approach to cavity fill. Yes, this is labor-intensive, but it is relatively easy to do, and you often can employ scraps of rigid foam or salvaged rigid foam insulation. The key is to not be too fussy about how your cuts fit, because you can’t cut it tight or well enough to be your air barrier anyway, so save the air sealing for later, when you spray foam all your joints and perimeters.Others have given solid guidance on choosing open-cell or closed-cell foam. On this, let me add that if you do choose a spray foam approach to cavity fill, be sure to use a certified installer.Evaluate your investment options. Martin and I just both wrote useful blogs on the topic of payback analysis – give those a look. Open-cell vs. closed-cell foamJean-Paul McGraw sums up some of the basic differences between these two types of insulation, including R-values and cost.“The advantages of closed-cell foam compared to open-cell foam include its strength, higher R-value, and its greater resistance to the leakage of air or water vapor,” McGraw writes. Spray Foam Insulation “The disadvantage of the closed-cell foam is that it is denser, requires more material, and therefore, is more expensive. Even though it has a better R-value, typically the cost per R is still higher than open-cell foam. The choice of foam can also be based on the requirements for the other performance or application specific characteristics such as strength, vapor control, available space, etc.”Open-cell spray foam has an R-value of about 3.5 to 3.7 per inch and typically uses water as a blowing agent, while closed-cell foam has an R-value of about 6 per inch, he adds.Costs, at least in McGraw’s area, average about 80 cents a square foot for open-cell foam and about $1.20 per square foot for closed-cell foam. With those R-values in mind, Jacobs will have trouble meeting energy code recommendations for his region if he goes with open-cell foam.“A house in [Climate Zone] 6 requires R-49 insulation in the attic,” Armando Cobo says. “If your intention is to have a conditioned attic, 7.5 in. [of open-cell] foam is R-28, then you also need 3 in. minimum rigid insulation on top of the roof decking. If you want to install [closed-cell] foam, you would require 7.5 in., and it can only be installed in 2-in. applications.”Cobo steers Jacobs toward a chart provided by Demilec, an insulation manufacturer, with more details.“The companies that are proposing 7 inches of open-cell spray foam for your roof are only offering R-26,” adds GBA senior editor Martin Holladay. “That isn’t much. In your climate zone, as Armando points out, you really want at least R-49. Don’t let a spray-foam contractor talk you into accepting insulation that is less than the minimum code requirements.” Scott Jacobs’ 1,100-square-foot Cape is a perfect candidate for an energy upgrade. The 90-year-old house is gutted, and Jacobs wants to insulate it well even if his budget is not unlimited.The house, located in Climate Zone 6, now has a 1/2-inch-thick layer of rigid foam on the exterior walls. Jacobs’ plan is to insulate the house from the inside with spray polyurethane foam.“This is my problem,” Jacobs writes in a Q&A post at GreenBuildingAdvisor. “Three companies have provided estimates now. Two say open-cell foam, 7 inches to 8 inches, on the roof and 3.75 inches on the walls. One company just quoted 7 inches of open-cell foam on the roof and 2 inches of closed-cell foam on walls. Estimates vary between $4,500 and $5,500.”First, Jacobs wonders, how do the 2 inches of closed-cell foam compare with 3 3/4 inches of open-cell foam? And second, for someone with not much money to spend, would installing rigid foam insulation in the rafter bays himself be a reasonable option?That’s the topic for this month’s Q&A Spotlight. RELATED ARTICLES last_img read more

Revisiting Heat-Pump Water Heaters

first_img This article is only available to GBA Prime Members About six years ago, I wrote an article for GBA called “Heat-Pump Water Heaters Come of Age.” Since then, manufacturers’ offerings have changed significantly, so it’s time for a fresh look at available equipment.My 2012 article mentioned five manufacturers of heat-pump water heaters: AirGenerate, General Electric, Stiebel Eltron, A. O. Smith, and Rheem. Two of these manufacturers have left the market. The first manufacturer to drop out was AirGenerate. (For more on AirGenerate’s trials and tribulations, see “AirGenerate and Electrolux Tier 2 Heat Pump Water Heater Units Removal.”)Toward the end of 2016, General Electric announced that it would stop making its GeoSpring heat-pump water heaters. A few months later, however, a rival manufacturer, Bradford White, purchased GE’s manufacturing equipment and began producing GeoSpring lookalikes under the Aerotherm brand. (For more information on GE’s exit from the heat-pump water heater market, see “Bradford White Buys GeoSpring Rights and Equipment.”)Bradford White sells the Aerotherm in two sizes. The 50-gallon model has a first-hour delivery rating of 65 gallons, while the 80-gallon model has a first-hour delivery rating of 87 gallons.Stiebel Eltron, the well-known German manufacturer of heat-pump water heaters, is still going strong, as are two American manufacturers, A.O. Smith and Rheem.Stiebel Eltron’s heat-pump water heaters are branded as Accelera heaters. They are available in two sizes. The 58-gallon model has a first-hour rating of 50 gallons, while the 80-gallon model has a first-hour rating of 74 gallons.For any consumers trying to make sense of the heat-pump manufacturing market, there’s a perplexing wrinkle to the story. The two best-known American manufacturers, A.O. Smith and Rheem, allow a very large number of appliance distributors to slap their own labels on the water heaters that they manufacture. The result is confusion.A.O. Smith sells Voltex heat-pump water… Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details.center_img Start Free Trial Already a member? Log inlast_img read more

Capital hit by football madness

first_imgThough cricket seems to have become our national sport, no Indian can entirely ignore football. School and college boys playing a fun game of football come rain or angry sun. Football is an adrenaline fuelled sport and the age old rivalries of East Bengal and Mohan Bagan or Brazil versus the rest of the world is legendary for football lovers. And thanks to the extensive sports coverage, footballs clubs from across oceans have found loyal fans in India. Also Read – ‘Playing Jojo was emotionally exhausting’Something closer to home, Noida witnessed a high-energy football tournament on 24 August. Nine spirited teams from various Bengali associations across Delhi and Noida clashed in the Pushpa Saha Memorial One Day and Night Football Tournament held at Kali Bari Ground, Sector 26, Noida. Aniel Kuumar Saha, CMD of SAHA Groupe, who is an ardent follower and supporter of the sport himself, sponsored the exciting event.The tournament was played with much vigour and enthusiasm by the teams to promote football, a game close to every Bengali’s heart. Anadi Barua, a former Indian international football player and the present coach of Indian women’s football team and India’s football team selector, graced the occasion as a distinguished guest. The games began at 3 pm and continued with rousing cheers for the competing teams till late night. The tournament was organised by the Noida Bengali Cultural Association.last_img read more