# Rigid Insulation on Exterior



## jklingel (Dec 21, 2008)

Google REMOTE wall. There is a prescriptive thickness of exterior rigid foam that is necessary to keep your sheathing warm enough to avoid getting condensation on it. I believe you need 4" of rigid over 2x6 walls, and 2" over 2x4; 6" and 4", respectively, is better. Check on greenbuildingadvisor.com, too. I believe the article is titled "How much foam is enough?", or similar. cchrc.org has info on the REMOTE wall, too, as they allegedly invented it.


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## Dragfluid (Dec 30, 2013)

Adding house wrap over your rigid foam will be a good improvement as well. Air infiltration really kills efficiency. 

Be sure to know how thick your walls are eventually going to be before you order your new windows. :wink:

Enjoy your warmer home!


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## Gary in WA (Mar 11, 2009)

Per your location, R-13 cavity fill with *R5 *rigid foam board will meet code and prevent cavity condensation;
http://energycode.pnl.gov/EnergyCodeReqs/index.jsp?state=Iowa


http://www.buildingscience.com/docu...ulating-sheathing-vapor-retarder-requirements

And you sure don't want/need to put the vapor barrier outside the sheathing to prevent it from drying outward. Fine for colder climates, not yours. R-5 will remove any interior vapor retarder/barriers from the mix. Use unfaced XPS and a drainable HW (stuccowrap or similar) if using a reservoir siding like cement board- or even a rainscreen application.

Gary


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## cibula11 (Jan 6, 2007)

So 1" of Owens Corning fomular insulation is R-5. My walls are older, true 2x4 with plaster and lath. Not sure if there's much, if any insulation in wall cavity. Could I do 1.5", which is R-7.5 or even go with a polyiso board and get R9.5?

I just don't want to skimp. It's going to add up anyway, but with frozen pipes and drafty rooms/windows, I want to make sure it's done the right way.


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## joecaption (Nov 30, 2011)

Why not just remove all the old siding? Then you could add the needed fire blocking, run new wiring, add R-13 insulation.
If this is a balloon framed house those walls are just acting like chimneys from under the house to the attic.


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## cibula11 (Jan 6, 2007)

joecaption said:


> Why not just remove all the old siding? Then you could add the needed fire blocking, run new wiring, add R-13 insulation.
> If this is a balloon framed house those walls are just acting like chimneys from under the house to the attic.


WE will be removing all the old siding, but not the old sheathing. That being said, the only way to add insulation to the interior cavities would be through tearing out drywall or spraying loose fill in, which has it's drawbacks. I know because of how windy it is at our home, I'd like to seal it up a bit by using foam board, just not 100% sure on thickness.


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## Tom Struble (Dec 29, 2008)

no,once the siding is removed insulation can be blown in through holes drilled through the sheathing

imo insulating the stud cavity is first in importance,additional outsilation second


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## jklingel (Dec 21, 2008)

dense packet cellulose will help air seal, but other measures are needed as well. i would not hesitate to pack it into your wall cavities. just make sure your receptacle boxes are sealed up, or they will get a ton of dust in them. as probably mentioned already, tape your rigid foam, too.


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## Gary in WA (Mar 11, 2009)

cibula11 said:


> So 1" of Owens Corning fomular insulation is R-5. My walls are older, true 2x4 with plaster and lath. Not sure if there's much, if any insulation in wall cavity. Could I do 1.5", which is R-7.5 or even go with a polyiso board and get R9.5?
> 
> I just don't want to skimp. It's going to add up anyway, but with frozen pipes and drafty rooms/windows, I want to make sure it's done the right way.


You can install the thickness you desire... PIC would work if you don't have an interior vapor barrier existing (poly). IMO, not faced board with DP cellulose. Putting all the insulation outboard is the optimum way, keeping the empty bays/sheathing/framing warm from rot, drying by the house HVAC system. DP; http://www.karg.com/pdf/Presentations/Dense_Pack_Cellulose_Insulation.pdf DIY it is not, the blower required is unavailable. I could run the dew-point temps for your location, largest city nearby.... 

Gary


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## jklingel (Dec 21, 2008)

Gary in WA said:


> DP; http://www.karg.com/pdf/Presentations/Dense_Pack_Cellulose_Insulation.pdf DIY it is not, the blower required is unavailable. I could run the dew-point temps for your location, largest city nearby....
> 
> Gary


are you saying that dense packing cellulose is not diy? if so, i'd beg to differ. maybe our using too many initials is getting us confused. my sister is horrible with that; i have to ask her who t.h. she is talking about almost every email. thanks. j


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## Fix'n it (Mar 12, 2012)

Tom Struble said:


> outsilation



:laughing: never heard it put that way before. makes sense.


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## Tom Struble (Dec 29, 2008)

4 or more inches of foam is crazy on a building not designed for it imo,there are too many roof overhang/window/flashing/vb/siding/roi issues to address that many existing houses aren't suitable imo


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## Gary in WA (Mar 11, 2009)

DIY with the box store blowers around here do not have the power to effectively dense pack to pressures on pages 3-5 of that link. Other places may vary, but most are for just blowing cellulose into an attic/wall without dense-packing. 
For those using a more powerful machine that can dense-pack, some tips; http://www.karg.com/pdf/Insulaton_density/Dense_packing_Allwein_and_Biddle.pdf

Gary
PS. found the missing link; http://www2.dupont.com/Tyvek_Weatherization/en_US/assets/downloads/Master%20Architect%20Binder/Technical%20Bulletins%20and%20Case%20Studies/Commercial%20Technical%20Bulletins/Tyvek%20with%20Exterior%20Insulation%20Building%20Science%20Bulletin.pdf
Perhaps; https://www.google.com/#q=outsulation&spell=1


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## jklingel (Dec 21, 2008)

Density in a wall need only by 1.5x that of normal settled (loose fill) cellulose, which is 1.5 pcf. The Force 2 blowers can achieve that density. Our Ho Depo carries the Force 2, and I was told that is typical for Ho Depo. This is from http://www.inteccorp.com/site/epage/112959_934.htm "Can I dense pack walls with all Intec machines? Yes, the D.O.E. (Department of Energy) requires a minimum outlet blower pressure of 2.9 for dense pack applications. Refer to your manual or call technical services at 800-666-1611". A tech bulletin at Intec says the Force 2 ships set at 3.4-3.5 psi. Densities of 3 to 4 pcf may be great, but I don't think they add significantly, if any, to the R value, and once cellulose won't settle, that's pretty well it, IMO. See http://www.cellulose.org/userdocs/TechnicalSpecifications/CIMA-TechnicalBulletin02.pdf for example. I used a smaller machine (which I bought), an Accu1, and was told it will dense pack walls well, too, as it puts out 3 psi. It did a real good job for me, as best as I can tell. The stuff under my window bucks is solid, as well as the 8.5' x 1' thick wall I did (all through mesh). My shop walls were packed through holes in the sheetrock, so I can not verify what the cellulose is like there. However, when I pulled the hose out of any hole, what was left in the cavity was pretty solid. I'll just have to hope on that job. Pack away, (wo)men!


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## cibula11 (Jan 6, 2007)

I'm near Des Moines, Ia.

Like I've mentioned earlier my home is over 100 yrs old. We know we'll never seal it up perfectly, but with blow in and riding board we're hoping to make it a bit more bearable and more energy efficient.


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## jklingel (Dec 21, 2008)

you'll see a huge improvement, no doubt about it. just attack every crack you can. good luck.


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## Gary in WA (Mar 11, 2009)

I’m glad that it worked out for you! A person needs to check locally on the blower…. I believe a wall requires more than 3# density to dense-pack; for the benefits, if you research it a bit. This from DOE training; “*Density display*: Take two small, thin cardboard boxes of the same size. Fill one with cellulose to the proper density (around 3.5 lbs/ft3); fill the other to a density that is less than recommended. Place the boxes side by side in front of a halogen lamp or other heat source. Let students view the boxes through an infrared camera to see the importance of proper installation density. Pass the boxes around the class to let students feel the difference in weight.” From; http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDoQFjAD&url=http%3A%2F%2Fwww.waptac.org%2Fdata%2Ffiles%2Fwebsite_docs%2Ftraining%2Fstandardized_curricula%2Finstaller_curricula_2.0%2F5_3g_lp_dense_pack_sidewall_insulation_2012_v2.0.docx&ei=HpbkUtSwA8LpoATDkYCoDw&usg=AFQjCNGYt8BKAJ4gku9Nv2KWGaKnHtEmYw&bvm=bv.59930103,d.cGU&cad=rja

Another one (DOE) from last May; “Cellulose insulation is used in both new and existing homes, as loose-fill in open attic installations and dense packed in building cavities such as walls and cathedral ceilings. In existing structures, installers remove a strip of exterior siding, usually about waist high; drill a row of three inch holes, one into each stud bay, through the wall sheathing; insert a special filler tube to the top of the wall cavity; and blow the insulation into the building cavity, typically to a density of 3.5 lb per cubic foot. When installation is complete, the holes are sealed with a plug and the siding is replaced and touched up if necessary to match the wall.” From; http://energy.gov/energysaver/articles/insulation-materials
If one is to dense pack, be sure to use a 1-1/8---1/4” filler tube, otherwise; the cavity is not dense-packed. http://www.insulationmachines.net/dense-packing-the-correct-way/ Problem with the box store blowers (my local HD only has a 2.3 psi blower- unsuitable to dense-pack) is the extensive use they get; the seals may be worn to give lower pressures unless you pressure gauge test check before use- so much so, they fall below the minimum psi to dense pack to 3.5#; pp. 23-“Construction example: 2 inches x 4 inches x 8 feet on 16 inch centers, 2.8 cubic foot cavity 
*CELLULOSE COVERAGE *​ 1.6 pound material density, 18.7 pound bag 
*Wall Pack Density Pounds Per Cavity *
4.0 pounds 11.2 pounds 
3.5 pounds 9.8 pounds 
3.0 pounds 8.4 pounds 
Average yield with Cellulose: 1.9 cavities per 18.7 pound bag
From: http://www.google.com/url?sa=t&rct=...hOX_AYKRZ7XQ8gATENmSwCw&bvm=bv.59930103,d.cGU
So, be certain to get the correct product weight per number/size of cavities (or fill a test panel); if one has less than average stated (3.5#), it wouldn’t get the optimum water-wicking capabilities by being less dense- notice the install difference for the 12-18” deep ceilings; http://www.nationalfiber.com/docs/H...seInsulationinSuperInsulatedBuildings0913.pdf
Air travel through dense pack (it is an air permeable insulation) is another concern. At 3.5# it is minimal, at 3# it is compromised, in fact not even considered in a “standards test” for the industry. Figs. 69, 70 show the drop from 3.5 to 4# density, just add that difference (.28 in the short, .09 in the long) to figure 3# density is a poor air barrier in a wall application. http://www.google.com/url?sa=t&rct=...nixodqk1u1mL14j5j3py2VA&bvm=bv.59930103,d.cGU
If one is going to dense-pack, IMO, get no less than 3.5#pcf to be effective as an air barrier and most effectively wick any water leaks away from the wood framing. Rent a stronger machine (with a plastic 1-1/4” x 10-12’ tube) and pressure test it with gauge/cavity math to be sure of “dense-packing”, otherwise it is a wasted effort. 



Gary


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## jklingel (Dec 21, 2008)

Yes, and then then you read this in places, like CIMA, The Cellulose Insulation Manufacturers Association: See article at http://www.cellulose.org/userdocs/T.../ConsumerUpdate04-InsulationEffectiveness.pdf) "The R factor of cellulose is approx 3.8/inch, and does not vary over a wide range of densities" (this is from memory, and may not be the exact wording. See the article.) In the previous link I posted, above, the Insul Contractors Assoc of Amer says 1.5 times the nominal settled density, which is 1.5 pcf. That did not come from my head. So, do we believe the government, or the folks who make and install the stuff? OK, so that one is a no-brainer; sorry about that! :laughing: My money is generally with the guys who make the stuff. From what I've been able to glean from all the places I've read and people I've talked to, the Goal, if you will, is to get it to not settle and the rest takes care of itself. High density is, apparently, better for acoustics, and that makes sense; mass is one of the big variables there. Robert Riversong has been using the Force 2 machines to dense pack (very thick) walls for many years, if not decades. I will banter no more on the subject, as it seems this is another bit of building science that has a tad of opinion associated w/ it. Either way, study and make your own call. Cheers.


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## Gary in WA (Mar 11, 2009)

The Force 2 machine and others (similar) are perfect for dense-packing. My concern was; my local Home Depot only carries a 2.3#psi machine, below the DOE requirements. Just ask the attendant before renting a machine if capable of 3.5#pcf, to Do It Yourself. 

I never mentioned the R-value, other than a slight hit it takes when dense-packing. It does loose some R-value and at 3.5# it is self-supporting; no settling over time compared to lesser densities, from some "who make the stuff"; http://www.greenbuildingadvisor.com/green-basics/video-dense-packed-cellulose-1

From a worker "in the field"; "Dense-packed cellulose is cellulose blown into a wall cavity until it reaches 3.5 lbs. per cubic foot — a.k.a. “dense.” From; http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/insulating-stud-cavities-existing-homes

The 1.5X you quoted was incomplete, read the rest from that 1998 paper; 
"The Insulation Contractors Association of America recommends a density of 1.5 times nominal settled density for side wall installations. Some manufacturers recommend an installed density of at least
3.5 p.c.f. in side walls.

8.3.3 Dry cellulose insulation can be installed in new
walls using temporary retainers that are clamped in place
to create a closed cavity. Insulation is blown into the
temporary cavity at sufficient density to keep it in place
when the retainer is removed. An installed density of 3.5
to 4.0 p.c.f. may be necessary."
--------------------------------------------
Or at lesser densities it may settle/fall out. My whole point is when you have the machine at install, go for it! = 3.5# minimum to get better air stoppage, better wicking of incidental water/moisture, and no settling (only with a tubing feeder). I don't see where/how this blew up and upset you, if so; sorry.

Gary


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