Insulation Sprayed On Underside Of Roof Deck

[Terrel L. Shields]

and blown-in fiberglass on the attic floors

I would rather blow in cow chips... The last thing in the world I want in a house is pink pather or its ilk. Again, R values mean nothing, Thermal mass means something. Blown in or solid cellulose is far superior - and with boric acid it won't have cockroaches and it won't burn...smolder maybe, burn no...

I helped my dad put fiberglass bats in their old house in the 70s. 20 years later those bats were not 1" thick and when cellulose was blown in the electric bill went from $90 to $45 a month.

BTW, if you really want to pay yourself money, install geothermal heat pump in properly sized tonnage. Will pay out in 5-10 years, far shorter if the current legislation that will mandate 30% "renewable" energy for electric generation passes. Electric rates will double in short order.

 

[Cigar]

Appraisers should be on the alert for these new "green" homes, the combination of sealing them up and building them with new "green" building materials is creating toxic homes. I've seen some where people are moving out and suing the builders, all the poor builders have done is built to the adopted new codes. some have formaldehyde levels higher than the infamous FEMA trailers. Many types of sprayed foams are loaded with formaldehyde, including the new so-called "soy-based" foams, all they do is add some soy to the same old formaldehyde based foams.

One of the most popular open-cell foams is Icynene, it doesn't contain formaldehyde but contain isocyanates, so I asked an industrial hygienist about it, she replied:

Isocyanates do not contain formaldehyde, but the health effects of isocyantes are similar. My toxicologist pal thinks isocyanates may be worse.

I would think it wise that an appraiser should recommend air-quality testing for any homes built under green codes or where foams are apparent to be sure there are no health issues. When people move out and sue because they are sick it certainly has to negatively impact value.

 

[Allan Edwards]

If foam will do that and provide energy savings, excellent. I just have never seen a home with the foam product here in Houston (retrofit or new). And I've never run into a builder that suggested foam over a barrier. I'm sure there are some, just never met em.

Mike

Spray foam up to the ridge with a sealed attic will moderate attic temperatures much better than radiant barrier. The main benefit is the entire HVAC system is encapulated into the building envelope, thus creating less strain on the system. You can also downsize the tonnage. People I know who have Icynene rave about their low electric bills.

It is an upgrade and does cost more than conventional insulation, but it is an option. I know Robert Dame is spec'ing it on his homes. By the way I build in Crestwood (Memorial Park), Tanglewood, Memorial, River Oaks, West U. Just started a very large custom at corner of Purdue and Auden.

Currently doing jobs financed by Compass Bank, Green Bank, and Frost Bank.

Allan

 

[Tim Hicks (Texas)]

Radiant barriers are one of the biggest myths out there. Many roofing companies will not warranty a roof with radiant barriers because it has adverse effects on the shingles greatly reducing their life as told to me by a few people. Foam insulation is installed in many low-e homes around here. They effectively make the home a sealed cooler and have no exposed windows to the sunlight. They advertize very low heating and a/c bills and separately meter them to prove it.

 

[Mike Plumlee]

Terrel - Fiberglass doesn't degrade. Cellulose does. That's the primary reason for my choosing fiberglass.

Allan - I was on Auden and Jardin yesterday. Amherst next week, I'll run by and shake your hand if you're there on Auden.

Tim - if the shingles are nailed to the deck boards and the radiant paint is sprayed on the underside of the deck .... how can that possibly affect the shingles? The paint doesn't touch the shingles and neither is active. I'm curious on that one. As to a radiant barrier being a myth, I don't think so. The question for consumers is to find the best way to create a barrier and maybe a sealed environment is equal or better.

 

[Mr Rex]

Most of the info I have read indicates that a radiant barrier increases the roof surface temperature by less than 5 degrees and many shingle manufacturers have extended their warranties to include installation over a radiant barrier. As to the question of how can a radiant barrier damage shingles, well there it is, when the barrier radiates the heat back out, it increases the roof surface temperature, and since the roof surface is the shingles, bada boom.

 

[Mike Boyd]

Title 24 anyone? Since 1979 all new construction must meet engineered heat loss calculations in order to get a permit.

 

[Terrel L. Shields]

Fiberglass doesn't degrade. Cellulose does.

can't buy that personally... but i can aver that you can ask 40 carpenters and 35 of them will tell you the following about any of the items that follow the questions ...

1. "It" [soup de jour] costs 'too much' [never mind it may save you money month after month.]

2. "Nobody" uses it. [Then why do I see so much of it advertised?]

3. "It" doesn't last as long.

4. "It" is prone to problems.

5. "It" sweats [or settles, or chips, or corrodes, or fades, ad neaseum].

Geothermal heat pump
Metal roofing
encapsulated crawl space
cellulose insulation
triple pane windows
thermal barriers
raidiant heat shields
Marathon hot water heaters
Instant hot water heaters

What is really amounts to is the carpenter cannot build it as cheap, doesn't know how to install it correctly, doesn't want to learn how to install it correctly, and is a slow learner...

http://www.cellulose.org/HomeOwners/FAQ.php
Which is the best insulation for the environment?
That’s easy – cellulose.
Cellulose insulation is made from at least 80% recycled paper, primarily newsprint, giving it the highest recycled content of any insulation product. Cellulose insulation also has the lowest embodied energy score of any major insulation. It takes less energy to produce and transport cellulose insulation, which means fewer emissions are released in manufacturing it. Fiberglass uses approximately 10 times more energy than cellulose insulation to produce and transport, while foam products, derived from petroleum, use even more. In addition, neither of these products is recyclable.3

What is the best insulation to use in a cold climate?
Studies by Oak Ridge National Laboratory show that the performance of fiberglass insulation degrades dramatically when the difference between the internal and external temperature exceeds 30 degrees, while the performance of cellulose remains stable.

http://www.resolutionenergy.com/cellulose_info.asp

Frequently Asked Questions

1. Does cellulose settle in attics or sidewalls?
   
   Cellulose will settle in attics until it reaches a stable density, as will other types of blown insulation. Coverage charts have already taken this into account. In sidewalls, cellulose will NOT settle if installed via tube feed method.
2. Is cellulose a “green” product?
   
   Yes, cellulose insulation is made from paper, which is refined into cellulose fiber. It has a local recycled content of 82%+. Fiberglass has less than 25% and sprayed foam insulation nearly Zero. Our product is made right here in New England, which means lower emissions, as our insulation travels fewer miles before it arrives to your home. This is one of the greenest products available.
   

1. Blown in cellulose insulation is treated for fire retardancy. If a fire occurs, the blown in cellulose insulation, combined with its fire retardants, can slow the fire from spreading and can create a "2-hour firewall". Scientists at the National Research Council of Canada report that, blown in cellulose insulation increases fire Fiberglass insulation is inert, ages well and is extremely difficult to ignite. However, once fiberglass insulation has been ignited, it may burn fast, hot and could emit toxic gases. Also, fiberglass insulation should be kept away from, light fixtures, chimneys or exhaust flu's to reduce heat build-up and potential fire hazards.resistance by 22%-55%. When Blown in Cellulose insulation does burn, it generally doesn't emit toxic chemicals.

2. [*]Blown in cellulose insulation is 2-3 times denser than fiberglass insulation. Studies comparing Blown in cellulose insulation Vs fiberglass insulation show that cellulose insulation was 38% tighter and required 26% less energy. A Princeton University study shows, a group of homes with blown in cellulose insulation in the walls had an average of 24.5% reduction of air infiltration compared to fiberglass insulation, with only the walls insulated. A similar study, the Leominster MA Housing Project for the Elderly found that, a building with blown in cellulose insulation compared to a building with R-13 fiberglass batt insulation in the walls and R-38 fiberglass batt insulation in the ceiling, had 40% lower leakage.
   [*]

   </SPAN>

PS - in centuries gone by, ice was cut from lakes in winter and stored in Ice houses. What was the insulating material they used? Sawdust.

 

[Mr Rex]

Fiberglass settles as it ages losing R-value, and the batts will pull away from the framing members as it settles, providing gaps in the insulated envelope. Blown cellulose also settles and loses some R-value as it ages, but the "wet" blown type performs similarly to the sprayed foams in the wall cavitiy and tends to maintain the envelope better than fiberglass.

 

[Mr Rex]

FWIW, Johns Manville has a fiberglass spray on product called Spider Fiber or JM Spider that has many of the same advantages of the spray foam and wet blown cellulose with the advantage of the inert nature of fiberglass. For a sealed attic, it requires a layer of spray foam on the underside of the sheathing and then spray on the Spider product since the spray foams are denser and prevent condensation on the underside of the sheathing, while the less dense fiberglass does not.