# Spray Foam Insulation or Regular Batt Insulation???



## mdaniel

I am pondering building a new home this year and have the most basic of questions to ask regarding insulation. It seems that most builders use traditional batt insulation in the walls and blown insulation in the attic. I have heard that foam insulation sprayed into the walls is far superior to batt insulation; is this correct? If so what are the cost differences per square foot between foam and batt insulation? I am considering building an ~ 2,200 sq. ft colonial and definitely want and need good windows and insulation to start with. Any advice or thoughts?? Any help is greatly appreciated.


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## muncybob

It's to my undestanding that the spray foam is initially more expensive but where it shines is the elimination of drafts. I believe a lot of the foams are equal to or greater in R value per inch vs. fiberglass. This is great as long as you have some sort of fresh air system to a well sealed up house to avoid possible condensation/mold issues in the future.


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## Ncountry

I would highly recommend spray foam in the walls of a house not so much for the attic.Foam has close to double the R value /inch and stops close to all air infiltration . Not only is fiberglass not as good of an insulator but it is rarely installed properly(cut and tucked around wires, elect box,ect..). In the attic I would go with blown in fiberglass or cellulose . This would allow house to breath eliminating most moisture problems and reducing costs significantly.


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## peakbagger

IMHO, I am not a fan of spray foam in walls with conventional framing and unless the installer does something special in the ceiling joists I dont think its worth the extra dollars. Obviously if you watch This Old House, it looks like the greatest invention of all time, but everytime I see them spray it into a house they level it with the studs and oh by the way, they get it installed for free or at a substantial savings. Even though the R value may be superior to fiberglass, the 2x6 framing is made of wood and it bridges from the outside wall to the inside with not a bit of foam to increase the R-value. Using 16" OC framing, that means 10 percent of each section of wall is the R value of wood. My preference is a 2x6 fiberglass insulated wall with 1" of foam board on the exterior or interior. Some folks advocate 2' on center framing with 5/8 inch sheetrock, to cut down on bridging but I expect that the studs would eventually telegraph. 

As for the argument that foam cuts down on drafts, thats true, if the contractor building the place doesnt do a good job crack sealing to begin with. Some states now require an air leak test prior to issuing a Certificate of Occupancy, I expect that contractors are a lot more careful in those areas (or push foam) as they typically dont get paid until the CO is issued. Realistically with air barriers, careful crack sealing, proper insulation installation and a real vapor barrier on the interior, drafts should not be an issue. 

Alternatively, skip the framing and go with stress skin panels, they go up super fast, they have no thermal bridging and they have incredible R-values. 

Of course anytime you use foam, be aware of carpenter ants. Granted a lot of contractors use termite barriers and claims it stops them, but I have heard of several cases where foam insulated walls were infested with ants despite the use of shields.


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## btuser

I would strongly suggest sprayfoam, if only for the reason that after 15 years of residential construction I've NEVER seen a perfect vapor barrier.  Either on the ceiling or especially in the walls, every time someone cuts an electrical box you get drafts.  

I think when building with spray foam, the advantages of the material should be used to change the way we build, therefore equalizing the costs.  If you don't need a vapor barrier inside, or house wrap on the outside, or ridge vent or soffit vent or whatever you can save there and use it to pay for the extra cost of spray foam.  I even think it makes the house stronger with the way it locks/glues the panels and studs together.  I'm not sure, but I think a 2x4 wall 24" OC with spray foam will give you the same as a 2x6 wall 24" OC with conventional insulation.


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## coolidge

If i were going to build a new house i would not skimp on the insulation part,it is something you cant change when the house is done without extensive remodeling. We all know oil is going to shoot back up when the economy recovers. Foam will be roughly three time more than fiberglass, but the house will be sealed and the foam will pay for itself with energy svings in four to five years. Yes you will need an air exchanger for the house to breathe, but as mentioned there are some savings on different building material that wont be needed. Also you could downsize you heating appliance if foam is installed.


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## btuser

Good point on downsizing the heating/cooling need of the house.  There is a little graph/chart that shows the law of diminishing returns when it comes to insulation, but you have to keep in mind that you're not looking for infinity but looking to keep your house warm/cool.   If you can reach a certain point either through solar gain/extra insulation or whatever you might be better off with electric baseboard!  Now you're talking 2 grand instead of 10 grand.   Some say electric heat is more expensive but in a house with under a 20k heat load what's the difference?

Maybe not in the attic/floors, but definately the entire building envelope.


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## richg

If you are building the house, I would pay the extra money and get spray foam in both the walls and attic. 

I was 1 micron from starting a spray foam insulation business in the fall of 2008, but backed off because the economy was crashing and the startup cost would have been close to 100K. That being said, there is simply no comparison between fiberglass batts, blown cellulose and spray foam. Many factors go in to this:

1. Spray foam acts as a total air infiltration barrier. Fiberglass and cellulose will allow air pentration, whether it is in the attic or walls. Spray foam is like tank armor, nothing gets in or out. 

2. Spray foam has a much higher R value than fiberglass or cellulose. Most spray foams are at about R7 per inch, while cellulose is only at R3 and fiberglass about the same. Mind you, this is for CLOSED CELL spray foam, not open cell. I would not recommend open cell spray foam even though it costs a lot less. 

3. Total cost: expect to pay about $1.00 per board foot (12 inches by 12 inches by 1 inch deep). ISpray foam will cost a lot more in the beginning, but its stunning efficiency will quickly pay for itself via decreased utility bills and comfort in your living space. 

4. Teh most crtical space for insulation is the attic. Heat rises, and any penetrations into the attic are a major source of heat loss (and money loss). Spray foam knocks out this problem via its sealing properties. 

5. Here is an actual photo of a massive air leak in my attic. I was having problems with high heat bills and forst and mold on the attic sheathing. turns out that warm, most air was leaking into the attic via peenetrations. I pulled all the fiberglass, and found that many sections were blackened from dust-laden air moving through the fiberglass. I shot an inch-thick layer of spray foam across the attic floor and then sprayed a foot of cellulose on top. My utility bills have been cut in half. 

Geth the spray foam and don't look back.


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## wenger7446

My wife and I put up an addition about two years ago and had spray foamed insulation installed.  The best money we spent on the place. 

Just do it!


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## Valhalla

Spray foam whenever possible! Nothing else is as
effective.


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## jimmy dean

Lets first asses the two choices you have limited yourself to: Foam= $$$$$$$ per installed foot, most are not closed cell. Fiberglass=Thermal looping, wind washing R-value degradation. ONE MORE MISSING ALTERNATIVE Cellulose insulation..
Installed as DENSE PACK in the walls, stops air movement acts as an effective vapor retarder and has R-values up to 3.77 per inch. In the attic.. Seal all penetrations, I use mineral expanding gun-able foam, seal wall caps, plumbing holes, wire holes, seal chimney holes with metal not foam. If you want Ventilation (soffit and ridge or gable) "Prpa-vents" with tightly rolled fiberglass
"plugs" pushed out to the outer edge of the eave walls backed with heavy packed cellulose. In your area R-45 value insulation in attic - 14-1/2" blown in BEFORE settling. Cellulose Dam at access hatch. 
If you want comfort without a big heat bill I just finished the third of six 12" roof framing, 12" walled, 1100 sqft all dense pack "cottages" on So. Burlington VT. Heated with Natural Gas 93% efficient thru the wall fireplaces as primary heat source, the heat is blown thru the HRV system in the houses, they are incredibility tight, warm and very efficient. 
If you have trouble finding a dense pack cellulose installer you might try contacting "National Fiber"..in Belchertown Ma. they may be able to refer you to a local installer.
20 years of dense pack/air sealing and going strong.


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## SolarAndWood

richg said:
			
		

> 3. Total cost: expect to pay about $1.00 per board foot (12 inches by 12 inches by 1 inch deep).



I assume this is if you have a guy come and spray a large area?  Seems like polyiso board is half the price and if you are remodeling you can do it as you go as opposed to having the whole house opened up?  3 sheets of 1 7/8" in the 2x6 stud bays, Tyvek outside the sheeting and 1" over the Tyvek gets you in the R45 neighborhood and should be airtight with the bridging issue minimized?  Then maybe a little DIY spray foam for those places that board would be tough to get in tight?  It is unfortunate that 1 7/8" is more than twice the price of 1".


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## richg

On an "inch vs inch" basis, polyiso board does ahve the same R value of spray foam, perhaps even a little higher as it is manufactured under tightly controlled conditions in a factory. On site spray foam cany vary a bit if the proportioner is off, drums aren't fully mixed etc. Polyiso also has a layer of radiant barrier applied which is useful for attic installations. However, the value of on-site spray foam is the absolute, total air infiltration barrier you get. Yes, you can cut polyiso boards to fit a cavity and then use gun foam to seal the gaps. That will still not even come close to spray foam in terms of R value and air-sealing properties. I went through this entire debate in my head for months before biting the bullet and going with spray foam.  Most contractors will have a minimum project size which is usally $2000.00 cash. In these dreadful economic times you might be able to find someone who will do it for far less. Some guys have a rig especially for small jobs, which is the Graco E-10. They can come in, shoot and scoot.


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## JayDogg

I just built a 3,000 sq. ft. colonial over the past summer, we live in western ma where it gets to the teens every night in the colder months.  I did the Spray Cellulose and couldnt be happier. It was quite a bit cheaper than the Spray foam and dont believe it is less of a product.  It still fills all the cracks and gaps between electrical boxes..etc.  One key to having a tight house is to go around with some "Great Stuff" for windows and doors and fill the areas around the windows and doors before the house is sheet rocked, you will get a good draft in these areas if its not done.  You could also get a bunch of silicone caulking and seal the bottom and top plates around the exterior of the house.  We could not be happier with the insulation in our house, and it is very quiet in there as well.  I have built about 6 houses over the years, and this one if buy far the best choice of insulation for me.  I have seen the spray foam insulation as well and it definitely does do a great job of insulating (not sure if I would say a better insulator that cellulose) but the price of cellulose compared to foam is probably 30% cheaper.


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## hkillam

Sprayed closed cell has an additional benefit not yet mentioned; flood survivability. I understand in some flood prone areas, this is the norm for insulation in new construction, far lower rebuilding costs as the insulation doesn't need to be replaced, and actually adds some rigidity to walls when the drywall fails.

However, be sure you've got all your electrical runs just the way you want them, cause you can't really pull new lines within a closed cell wall like you can in fiberglass batts. Not sure, but some municipalities may require sealed (foam proof) conduit for all walls where foam will be sprayed. Again more expense, but less expense later if you ever need to pull replacement wiring within existing conduit.

Personally, in new construction, I'd go foam for the reasons already listed in previous posts. I do agree with the drawback of thermal bridging in studs, but that is present with foam, blown cellulose, fiber batts, etc. Some rigid foam board between outside exterior walls and the outside finish addressed this, and makes a lot of sense, plus doesn't need much trimming versus the rigid foam boards cut to wall cavities.


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## semipro

mdaniel said:
			
		

> I am pondering building a new home this year and have the most basic of questions to ask regarding insulation. It seems that most builders use traditional batt insulation in the walls and blown insulation in the attic. I have heard that foam insulation sprayed into the walls is far superior to batt insulation; is this correct? If so what are the cost differences per square foot between foam and batt insulation? I am considering building an ~ 2,200 sq. ft colonial and definitely want and need good windows and insulation to start with. Any advice or thoughts?? Any help is greatly appreciated.



As muncybob and others alluded to, don't underestimate the value of inhibiting air infiltration.  You can insulate a house really well and still have a cold and drafty house and high utility bills if its not airtight.  It helps to keep critters out too. Don't worry about making it too tight as you can always add a heat recovery ventilator and then *control *the quantity and quality of air that enters while recovering the heat.  That's nice for allergy sufferers too.


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## prink3

I recently did a major addition and remodel in my house.  I had the same conflict with performance over price.  I went with batt in the studs, 1/2" sheathing, and 1" Polyiso board on the outside.  The reduction of bridging is big, but reducing infiltration is bigger.  I addressed this by caulking and can foaming everything in the walls, caulked and taped the board insulation, plus I used a liquid applied (like paint) air barrier on the outside of the sheathing.  It was a commercial product called Sto Emerald coat, but I found several others.  I went with this package because the performance was close to sprayed foam, but much of it was DIY, and was 20% the cost of foam.  If I could have afforded a bigger budget and was paying for an installed insulation package, I probably would have gone with foam.  

Regardless of your decision it is still important to seal between floors and walls well, no more than one vapor barrier in a wall, and use efficient framing that causes less thermal bridging.


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## jimmy dean

What all this chin music sugars out to.. using dry dence pack cellulose (and airsealing open attics and around windows & doors) I can get a house 99% as tight as a foam house, with out converting food (soy) or OIL - anybody making new oil latly? for about half the $$$$ for new houses and 1/3 the $$$ for retrofit. Oh Ya Bug and mice hate cello, while foam and that pink fuzzy stuff provide warm wonderfull homes for them.  Build'em tight.. Vent'en right- Jim Fitsgerald (the master densepack cello man).


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## richg

Good thread here. We have listed the pros and cons of the major types of insulation, and now it's up to the buyer/user to make the decision. Which ever way he goes, I am heartened to see people paying so much more attention to energy conservation. Group hug time.


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## SolarAndWood

richg said:
			
		

> I am heartened to see people paying so much more attention to energy conservation.



Its amazing how much more you pay attention to it when you are producing the fuel instead of just paying another bill.


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## ChillyGator

Had open cell foam sprayed under my wood floors (open crawl space-no insulation prior) yesterday.  Called for a minimum 3.5" between floor joists but it looks a lot more like 5"-6" was actually put up  :coolsmile:  Actually had some foam come up thru my heart pine floors in two places  :bug: 

Already could tell the difference, 48* outside/furance set at 63* inside/actually temp was 65.5* inside @ 6:00pm last night (had left the wood stove stoked up prior to leaving for work yesterday).  Last night temps got down to 30* but I had to run much smaller fires to keep my living room under 80*

I don't think the furnace ever came on last night.  WOW this is gonna save me big $$ on propane and reduce wood consumption....LIFE IS GOOD!

will try to add pics when I get the chance.


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## caber

We just put on an addition.  We wanted to do the spray foam but absolutely choked on the cost.  We did the framing at 2x6 and to fill it up was outrageous.  They also suggested 1-3 inches of foam and additional bats to get the R value up and the was only slightly less cost prohibative.  We ended up with the dense pack cellulose.  Great product.  Slightly more than fiberglass, great barrier.

ChillyGator - we have the same issue as you did with the original part fo the house.  It is up on an open pier foundation.  There are batts in the joists, but they don't do a great job of keeping the floor warm in the winter.  When we get a day where the wind is in the 20s and up, the wind really pushes the cold air thru the batts and chills the floor.  It's the biggest heat suck in the house.  We had a company look at it with the thought of doing spray foam to seal the floor and they claimed it would be too difficult to install.  The guy said since they would be crawling around they could not keep a steady and open stream and the nozzle would keep clogging and we would pay a fortune in nozzles.  I'm looking at alternatives to seal up the underneath.  My current idea is insulated sheathing in the bays with spray foam around the edges, followed by a layer of batts and then a vapor barrier.  I'm working on getting concrete blocks to build a wall around to make it more of a crawl space versus open pier. 

Anybody have experience with the DIY spray foam kits?


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## ChillyGator

At first I was concerned that the installer could not get to all of my crawlspace (very tight in the front of the house) but he assured me after looking at it that "we grease em up and slide em in very tight places".......he was not kidding!

First looked into this last summer and was quoted $1.60 sq ft for 3.5" of foam.......when I checked back after the first of the year I was quoted $1.30 sq ft and interest free financing for a year.  

I think my guy wanted work for his crew and to get the word out in my area concerning retrofitting older homes.  Worked for me!


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## ilateapex

Another option is to do what is called a "flash and batt".  This is where they come in and just put a thin coating of the foam, say 1/2" or so to seal everything up and then install traditional fiberglass batts.  This also can be done using netting and loose fill if you choose.  Another thing to consider is to make sure all the HVAC and Duct work is in the conditiond space.  Makes a big difference.  On a current project we are doing, we have to foam the roof deck so that attic is part of the conditioned space just for the HVAC.  And install and ignition barrior as there is no sheetrock over the insulation.

Good Luck

Michael


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## coolidge

Caber,    If your going with blocks around the perimeter you could spray them instead of the floor.     Flash-n -batt syatems have there place in the insulation world. I talked to a man with extensive knowledge of sprayfoam and he was a little concerned with spraying half to one inch of foam and then fiberglass or cellulose. The condensation point could very well be between the two, which would really suck.


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## caber

coolidge said:
			
		

> Caber,    If your going with blocks around the perimeter you could spray them instead of the floor.     Flash-n -batt syatems have there place in the insulation world. I talked to a man with extensive knowledge of sprayfoam and he was a little concerned with spraying half to one inch of foam and then fiberglass or cellulose. The condensation point could very well be between the two, which would really suck.



That's an interesting thought.


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## StackedLumber

ilateapex said:
			
		

> Another option is to do what is called a "flash and batt".  This is where they come in and just put a thin coating of the foam, say 1/2" or so to seal everything up and then install traditional fiberglass batts.  This also can be done using netting and loose fill if you choose.  Another thing to consider is to make sure all the HVAC and Duct work is in the conditiond space.  Makes a big difference.  On a current project we are doing, we have to foam the roof deck so that attic is part of the conditioned space just for the HVAC.  And install and ignition barrior as there is no sheetrock over the insulation.
> 
> Good Luck
> 
> Michael



We're in the process of a 7000 sq. ft new build and we are doing this very same process of "flash and batt" in the side walls, However, our foam coating is 2 inches w/ fiberglass batts on top of that.  Personally, for where we live and length of heating season, I kind of think that only 1/2 in. is a bit light-but it a diff. climate it probably would be okay.  The sub said that we'll accomplish at least an R-28 value in our sidewalls, brings the cost down not going the full 5 1/2 for the sidewalls.


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## Gooserider

caber said:
			
		

> We just put on an addition.  We wanted to do the spray foam but absolutely choked on the cost.  We did the framing at 2x6 and to fill it up was outrageous.  They also suggested 1-3 inches of foam and additional bats to get the R value up and the was only slightly less cost prohibative.  We ended up with the dense pack cellulose.  Great product.  Slightly more than fiberglass, great barrier.
> 
> ChillyGator - we have the same issue as you did with the original part fo the house.  It is up on an open pier foundation.  There are batts in the joists, but they don't do a great job of keeping the floor warm in the winter.  When we get a day where the wind is in the 20s and up, the wind really pushes the cold air thru the batts and chills the floor.  It's the biggest heat suck in the house.  We had a company look at it with the thought of doing spray foam to seal the floor and they claimed it would be too difficult to install.  The guy said since they would be crawling around they could not keep a steady and open stream and the nozzle would keep clogging and we would pay a fortune in nozzles.  I'm looking at alternatives to seal up the underneath.  My current idea is insulated sheathing in the bays with spray foam around the edges, followed by a layer of batts and then a vapor barrier.  I'm working on getting concrete blocks to build a wall around to make it more of a crawl space versus open pier.
> 
> Anybody have experience with the DIY spray foam kits?



Another option that I've heard of people doing, don't know how well it works, is to fill the joist cavities with batts or other techniques, and then put up an inch or two thick layer of foam boards on the underside of the joists, being careful to tape and seal all seams, penetrations and so forth...  

Gooserider


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## coolidge

StackedLumber,    What kind of foam are you using? Open cell or closed cell? Open cell at 5.5" should yeild around R-20. Cl;osed cell at 3" should be close to R-21.


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## StackedLumber

coolidge said:
			
		

> StackedLumber,    What kind of foam are you using? Open cell or closed cell? Open cell at 5.5" should yeild around R-20. Cl;osed cell at 3" should be close to R-21.



I believe it's a urethane spray foam which I believe is a closed cell foam, but I may be mistaken and can ask the sub cont. on Monday for the exact details and specs., but I'm almost positive that the urethane spray foam in considered "closed cell".  We having done a full 3", only 2" plus batting on top of that.


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## StackedLumber

The explanation I got from the sub was this.  It is a closed cell foam that yields (supposedly) a 7-7.2 per inch R value.  So what they are doing is a 2 inch application of the foam and then R-12 batts on top of the foam.  I told him by my math that would give us r-26, not r-28 and he answered-I guess you could say that.  

Anyways, overall i think the point is that the spray foam goes leaps and bounds into eliminating drafts and other "unwanted" guests (flies, ladybugs, etc. etc.) from entering the sidewalls.  To me, insulation should be about eliminating air infiltration just as much as heat retention.


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## semipro

jimmy dean said:
			
		

> What all this chin music sugars out to.. using dry dence pack cellulose (and airsealing open attics and around windows & doors) I can get a house 99% as tight as a foam house, with out converting food (soy) or OIL - anybody making new oil latly? for about half the $$$$ for new houses and 1/3 the $$$ for retrofit. Oh Ya Bug and mice hate cello, while foam and that pink fuzzy stuff provide warm wonderfull homes for them.  Build'em tight.. Vent'en right- Jim Fitsgerald (the master densepack cello man).



Jim, would you recommend using DPC in a cathedral ceiling?  I've always worried about the effects of small roof leaks soaking into the cellulose and causing a catastrophic ceiling failure when the wallboard finally gives way.  Is that a reasonable concern?


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## Hankovitch

Hankovitch here,
I feel compelled to add my $0.02 worth. 
There is an article which gives details on how and why Sprayed Polyurethane Foam is so good, and cites a number of real world scenarios. Some of the information in the article addresses several of the claims of writers in this thread. With data and evidence from several actual jobs which (a) supports some of the writers in the thread, and (b) shoots holes in claims of other writers in the thread. I shall let the article speak for itself. Link to the article is:
http://www.monolithic.com/stories/foam-chapter-04
Additionally...
SPF in between your studs will increase the racking strength of your walls by a factor of 3x to 4x - you will have a stronger house.
SPF will function as a sound insulator. Do you live in a city? - you will hear less traffic noise.
Anyone who says that you should not put SPF in your ceiling or attic or cathedral ceiling is simply letting you know of their ignorance - reading the above article certainly disabused ME of MY ignorance!
My wife and I have researched this for several years, and we would not even consider anything other than Closed-cell (this means 3 pounds per cubic foot density) Sprayed Polyurethane Foam.  We have a good friend who is an architect tell us that if we used SPF in the 25' high gothic arches of our barn-to-be-home we MUST (her emphasis) leave the 2' space between every fourth or fifth arch open (no insulation), from floor to roof peak, so the house could breathe. My wife and I looked at each other in total disbelief - and with those respective looks we silently communicated, "she just talked herself out of designing our home."...and she did not even know what her ignorance had cost her.
I have other links to a variety of sites where various well respected agencies report data on various positive aspects of SPF, not even touched on here. If you'd like them I can send them to you - and I'll let you post them here if you'd like.
Email address is  ---  hdaum@tds.net.
There's nothing more satisfying than knowing you have made a well-informed decision.


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## Hankovitch

Hankovitch again,
I read more in this thread, and found the below and other similar comments to be of great interst....
"Another option is to do what is called a “flash and batt”. This is where they come in and just put a thin coating of the foam, say 1/2” or so to seal everything up and then install traditional fiberglass batts. This also can be done using netting and loose fill if you choose. Another thing to consider is to make sure all the HVAC and Duct work is in the conditioned space. Makes a big difference. On a current project we are doing, we have to foam the roof deck so that attic is part of the conditioned space just for the HVAC. And install and ignition barrier as there is no sheetrock over the insulation.
Good Luck,    Michael"
I agree with Michael........with one minor modification, have them spray Closed-cell SPF at 1 and a half inch...then the fiberglass batts.
The articles I've read present convincing arguments that this is an inexpensive and very viable alternative to 3" of SPF.
When cost is an issue, this oughta be a superb choice.
All-the-best! Hankovitch


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## woodsmaster

If I were building a new house I would have cellulose installed in walls and attick. there is a methed of spraying it in the stud cavities on walls slightly damp and then it dries crisp and then they brush it off flush
with studs with a power rolling brush. It wont settle. It has boric acid in it to deter bugs, and most important it's not flamable like spray foam! Its allso much cheaper than foam and fiberglass. No voids like are commen in  fiberglass batts. Foam is a good product but if you use it make sure you have ventalation or you will have mold problems. Im a contractor and I prefer cellulose.


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## Hankovitch

Hello, Interesting post, particularly so since you are a contractor. My wife and I have spent a great deal of time researching insulation alternatives, and we find a strong consensus that at least one inch of Closed-Cell Foam Insulation can be an excellent and very likely the best investment one can make in their home. This is based on some essential assumptions. Assuming you are using some common siding and roofing...The foaming must be done (a) after the rough-in of electric and plumbing, (b) after the siding is on, (c) after the roofing is done, and (d) perhaps also after HVAC ducting is done. 
The one inch of closed-cell foam will plug any and all holes, will function as an air barrier and as a vapor barrier - thus eliminating the necessity of purchasing and installing TYVEK or an equivalent 'house wrap'. (After installing your Tyvek house wrap, which is supposed to function as your air and vapor barrier, you will punch several thousand holes in it when you put on your siding, how wise is that?!). See also this link for compelling information from a site where they are not selling insulation, just presenting facts, as well as information from users as well as contractors...http://www.monolithic.com/stories/foam-chapter-04

If you apply the one inch of closed-cell foam after you do (a) through (d) mentioned above you will have an impenetrable seal of your home. Is it not true that moisture-laden air movement through insulation is the source of the water (and nutrients carried as 'dust' with the air/moisture mix) which the mold must have to grow? The one inch of closed-cell foam stops all those air-leaks, and stops convective flow of moisture-laden air. With this air movement stopped you need not worry about mold. Now the home owner can proceed with adding more foam if money is not an object, or they may choose to add a less expensive alternative insulation to fill the remainder of the wall, ceiling, attic cavities. 
I do like your idea of spraying the cellulose into a moistened cavity. I have read in numerous places that a 'skin' will form much as you describe, and additionally that settling will be at worst minimal. I can understand that the cellulose could be better than fiberglass batts (paper-backed or not), no matter how careful the installers of the fiberglass batts were.  Wouldn't it therefore be wise(est) from an economical perspective to use 1" of Sprayed, Closed-cell Foam, then use 'your' cellulose application to complete filling the cavity?

Have you ever done a side-by-side comparison of closed-cell foam vs cellulose - one house done with foam and another very similar style and square footage home done with cellulose? Have you ever done a side-by-side comparison of a home where they used just 1" of closed-cell form + cellulose for the remainder vs just cellulose? It would be very interesting to get a year's energy use data on those homes and compare. I wonder if anyone reading this thread has any personal information to share, or if anyone reading this knows where to 'send' us all for actual comparative data.....????

I do not believe there will be a problem with mold if you use Sprayed, Closed-cell Foam.  Everything out there argues very strongly that it will not be a problem.  The above link addresses this issue fairly well.


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## woodsmaster

Hankovitch said:
			
		

> Hello, Interesting post, particularly so since you are a contractor. My wife and I have spent a great deal of time researching insulation alternatives, and we find a strong consensus that at least one inch of Closed-Cell Foam Insulation can be an excellent and very likely the best investment one can make in their home. This is based on some essential assumptions. Assuming you are using some common siding and roofing...The foaming must be done (a) after the rough-in of electric and plumbing, (b) after the siding is on, (c) after the roofing is done, and (d) perhaps also after HVAC ducting is done.
> The one inch of closed-cell foam will plug any and all holes, will function as an air barrier and as a vapor barrier - thus eliminating the necessity of purchasing and installing TYVEK or an equivalent 'house wrap'. (After installing your Tyvek house wrap, which is supposed to function as your air and vapor barrier, you will punch several thousand holes in it when you put on your siding, how wise is that?!). See also this link for compelling information from a site where they are not selling insulation, just presenting facts, as well as information from users as well as contractors...http://www.monolithic.com/stories/foam-chapter-04
> 
> If you apply the one inch of closed-cell foam after you do (a) through (d) mentioned above you will have an impenetrable seal of your home. Is it not true that moisture-laden air movement through insulation is the source of the water (and nutrients carried as 'dust' with the air/moisture mix) which the mold must have to grow? The one inch of closed-cell foam stops all those air-leaks, and stops convective flow of moisture-laden air. With this air movement stopped you need not worry about mold. Now the home owner can proceed with adding more foam if money is not an object, or they may choose to add a less expensive alternative insulation to fill the remainder of the wall, ceiling, attic cavities.
> I do like your idea of spraying the cellulose into a moistened cavity. I have read in numerous places that a 'skin' will form much as you describe, and additionally that settling will be at worst minimal. I can understand that the cellulose could be better than fiberglass batts (paper-backed or not), no matter how careful the installers of the fiberglass batts were.  Wouldn't it therefore be wise(est) from an economical perspective to use 1" of Sprayed, Closed-cell Foam, then use 'your' cellulose application to complete filling the cavity?
> 
> Have you ever done a side-by-side comparison of closed-cell foam vs cellulose - one house done with foam and another very similar style and square footage home done with cellulose? Have you ever done a side-by-side comparison of a home where they used just 1" of closed-cell form + cellulose for the remainder vs just cellulose? It would be very interesting to get a year's energy use data on those homes and compare. I wonder if anyone reading this thread has any personal information to share, or if anyone reading this knows where to 'send' us all for actual comparative data.....????
> 
> I do not believe there will be a problem with mold if you use Sprayed, Closed-cell Foam.  Everything out there argues very strongly that it will not be a problem.  The above link addresses this issue fairly well.



Wanted to respond to your post. I'm not an insulation contractor so I don't have the numbers to compare, but there have been blower door tests done. If you go to the Nu-wool website you may be able to find the info there.
I Know they foam any cracks and around electrical boxes etc. before sprying the cellulose. Netting is used on walls that dont have a backing on to spray such an interior bath wall you may want insulated. Don't know if 
cellulose would stick to foam or not. I would use house wrap regardless to repeal any water that may get behind siding. It is also made from100% recycled material and takes 10 times less energy to produce than fiberglass


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## nojo

Has anyone had any experience with a Direct Under Roof Spray? We have an unfinished attic. It was roofed in the last couple years (before we bough it). Who ever roofed it, just roofed over the slat bords and did not put down new decking. I can see the underside of the shingles from inside the attic. There is no venting in the roof at all. I was told a direct roof spray would be my best option. The big question I have is when its time for a new roof, the foam will be bonded to the old shingle bottoms so when tey are removed and the new roofing/decking applied they will leave an air gap. Unvented air gaps = moisure created by dew points right? But if the foam is a vapor barrier from the house side, then no moisture should be able to come through the house and get trapped? Am I too worried about this? The other option is to do a shitlowd of work and cut in vents where they can go the I will lose over an inch of insulting space. WHich I only have 5 inches of anyway. We plan to finish the attic at some point.


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## Hankovitch

nojo said:
			
		

> Has anyone had any experience with a Direct Under Roof Spray? We have an unfinished attic. It was roofed in the last couple years (before we bough it). Who ever roofed it, just roofed over the slat boards and did not put down new decking. I can see the underside of the shingles from inside the attic. There is no venting in the roof at all. I was told a direct roof spray would be my best option. The big question I have is when its time for a new roof, the foam will be bonded to the old shingle bottoms so when they are removed and the new roofing/decking applied they will leave an air gap. Unvented air gaps = moisture created by dew points right? But if the foam is a vapor barrier from the house side, then no moisture should be able to come through the house and get trapped? Am I too worried about this? The other option is to do a shitlowd of work and cut in vents where they can go the I will lose over an inch of insulting space. WHich I only have 5 inches of anyway. We plan to finish the attic at some point.



Interesting query. I will speak with the gentleman who will spray our roof (outside application), and get his take on this. He has been using SPF for over a decade, and likely has run across your situation - we'll see. 

Regarding your concern about unvented air gaps, and in particular the situation present 15 years from now after a tear-off and re-roofing job. I don't believe this should present a problem, since I am certain you are correct that the foam acts as your vapor (and water) barrier INside, thus you won't have any moisture problems at all. 

I cannot imagine that going to the trouble of creating a boatload of vents would be necessary.

I will post again once I get a reply from the guy doing our spraying.

Sincerely, Hankovitch in SW Wisconsin


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## nojo

Hankovitch said:
			
		

> nojo said:
> 
> 
> 
> 
> Has anyone had any experience with a Direct Under Roof Spray? We have an unfinished attic. It was roofed in the last couple years (before we bough it). Who ever roofed it, just roofed over the slat boards and did not put down new decking. I can see the underside of the shingles from inside the attic. There is no venting in the roof at all. I was told a direct roof spray would be my best option. The big question I have is when its time for a new roof, the foam will be bonded to the old shingle bottoms so when they are removed and the new roofing/decking applied they will leave an air gap. Unvented air gaps = moisture created by dew points right? But if the foam is a vapor barrier from the house side, then no moisture should be able to come through the house and get trapped? Am I too worried about this? The other option is to do a shitlowd of work and cut in vents where they can go the I will lose over an inch of insulting space. WHich I only have 5 inches of anyway. We plan to finish the attic at some point.
> 
> 
> 
> 
> Interesting query. I will speak with the gentleman who will spray our roof (outside application), and get his take on this. He has been using SPF for over a decade, and likely has run across your situation - we'll see.
> 
> Regarding your concern about unvented air gaps, and in particular the situation present 15 years from now after a tear-off and re-roofing job. I don't believe this should present a problem, since I am certain you are correct that the foam acts as your vapor (and water) barrier INside, thus you won't have any moisture problems at all.
> 
> I cannot imagine that going to the trouble of creating a boatload of vents would be necessary.
> 
> I will post again once I get a reply from the guy doing our spraying.
> 
> Sincerely, Hankovitch in SW Wisconsin
Click to expand...


Hankovitch,
Wow Thanks so much. That would be great!


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## Hankovitch

Hello,

I received the reply from Scott Waste, of NES Building Solutions.
If you have additional questions, I am sure he would communicate with you.
You may reach Scott Waste by email at [info@nesbuildingsolutions.com]
And his Web Site is http://nesbuildingsolutions.com/

Below is Scott's email to me.............
Hank, What you and this home owner are talking about is what we call a "hot roof system". 
I believe in the system for insulating -  as I did it to my own house over 7 years ago . 
When you apply the closed cell foam to the underside of the roof deck you are creating a non-vented attic and or air space. Please note also that this technique for applying will void many of the shingle manufacturers' warranty. I hope at least the roofer laid down tar paper, then the shingles. 

Note that during tear-off of the shingles at a later date they will just have to be a bit careful not to 'pull' or just 'rip out' the nails... but more to tear or cut along the top of roof boards to try to cut off nails of possible,  and to thereby minimize disturbing or damaging the foam. 
By using closed cell foam they will get a vapor barrier and air barrier all in 1 system --- at a depth of 2 inches or more of foam. 
Another option they have is to install air shoots from the eve to the ridge and then make sure they have eve vents and a ridge vent. Then spray the closed cell foam on the underside of these 'air shoots'. This must be done in every cavity. If they have different pitches and or dormers, then you will have fewer cavities  that can be vented by this technique.
A final idea (assuming the roofers did not put tar paper over roof decking before shingling) would be to put tar paper on the underside of the decking prior to foaming.....extra work, but do-able.

A note added by Hank - perhaps if the roof boards are pretty tight (let us say gaps between boards a quarter inch or so), then perpaps they could apply the foam, and not worry TOO MUCH when they do the eventual shingle tear-off some years from now.

Sincerely,

Hankovitch in SW Wisconsin


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## begreen

Building Science corp. has some good information on insulation options. There are several good articles in the Digests section of their website. For roofs, this document may be helpful. 
http://www.buildingscience.com/docu...pitched-roof-construction/?searchterm=pitched roof insulation

general ventilation primer:
http://www.buildingscience.com/docu...-before-you-ventilate/?topic=/doctypes/primer


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## RobC

I had some Icynene, open cell, sprayed in our ceiling cavities and think it's great. Im writing in because of the "Flash and Batt" idea. I sprayed my propane storage tanks with closed cell foam and ran into problems. When I sprayed the foam on the tanks it did not loft. The reason was that the tanks adsorbed some of the heat that the foam self generates to loft. 
How this applies to Flash and Batt. In reading up on foam installation there are many thing that can effect the quality of the job. One rule of thumb is to spray product on, in, 2 to 3 inch layers. This is directly related to the exothermic reaction ( I was taught that word by a Boiler Room Member I'm not that sharp ) of the foam's 2 part properties. If you go less than 2 inches you don't have enough foam to complete the reaction. Not enough foam mass to build up it's own internal heat to loft. If you go with 4/5/6" you can cook your finished product and have cracks etc.
The other problem was mentioned in a previous post, it puts the vapor barrier on the wrong side of the fiberglass. Yes you can make a case that there won't be any air movement because of the foam but.........
Like any professionally installed product applicators experience, ambient temperature and humidity also play a factor.

I have also read about spraying the underside of the roof. That is a correct application and vents are not required. You need to make sure you get the complete roof and end walls down to the walls below because you will now have warm moist air in attic space and if you have any voids you will get condensation or ice build up at those points. Then mold.

Icynene has a great web site for Q & A that you can read up on. Where you don't want to foam is any where there is a possibility of a leak. Under tubs, washers and the like. It does afford nice noise dampening characteristics but if there is a leak the water needs to get out and not get trapped in or on the foam. This will create a mold situation.
Rob


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## coolidge

Rob,

       What was the temperature of your tanks when sprayed? I sprayed my tank and didnt have any problems. Spray the ubderside of the roof deck with closed cell( 4-5") to make it a hot roof. When its time to replace the shingles it might take a bit longer to trim any foam down that has filled the gaps, use some ice and water sheild and find a shingle manufacturer that does warranty there shingles( Certainteed, Elk are the oly two i know of right now). Then REAP the benefits.

Note: Do not use open cell, you dont have enough rafter depth to get the required R-value.


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## RobC

Tanks were some where about 80+F. They were warm to the touch. I know the product I got was fresh and I had it to the proper temp before spraying but frankly the second coat didn't loft the way it should of either. The only up side was that the manufacturer gave the local distributor a freebie kit so when all said and done I have about 3" to 4" of coverage. 
Have a good one Rob.


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