These are comments from builders about what types of insulation they are using. Dense pack cellulose seems to be more popular than fiberglass batts. I think the third guy has the best information.
(https://i56.photobucket.com/albums/g166/jraabe/insulation_survey.jpg)
Here's a link to This months Survey (http://www.jlconline.com/cgi-bin/jlconline.storefront/EN/UserTemplate/78?Section=CurrentSurvey&Action=Add&Productnr=0912survey) (may not work after Dec 09):
I personally find the pink fiberglass insulation very easy to put up. Its easy to cut to shape, fairly cheap. I have not tried spray foam, but holmes on homes raves about it. But im the kinda guy who likes to do the work myself, and i havent seen any do it yourself spray foam kits at any stores or anything.
This was advertised in Fine Homebuilding magazine as a spray foam option for DIYers:
http://www.rhhfoamsystems.com/index.php
Not checked into it other than looking at the web site....
They exist but OMG they are pricey. I looked at DIY foam kit to do my kit ~640 square feet of roof to an R40 level and it was $500 for fiberglass and roughly $3000 for spray foam, you can guess which I picked.
Pretty much all the builders around here who are building better quality homes are using wet blown in cellulose. It is not a DIY proposition. The blower is similar to the dry blow-it-in-your-attic types, but there is also a water mist sprayer. It takes some experience to learn the proper amount of water. It also takes experience to be able to blow pack enough cellulose into the wall cavities to get the right density. That why it's called dense pack. Then it has to be allowed to dry. A quality installer measures the moisture content over a period of days - weeks maybe. It has to dry down to a certain point before he will allow the interior walls to be finished.
All the nooks and crannies get well packed with cellulose. There are no gaps anywhere. Spaces behind electrical boxes, behind pipes and wires are all nicely packed. It's actually beautiful to see. Even taking my time there is no way I could achieve the same well insulated wall using fiberglass batts. I did my best but I just know it is not as good as a professional cellulose installer could achieve. I would have had our cabin done with blown in wet cellulose but I could not find a contractor who would do the job without an exorbitant surcharge for driving up into the mountains. In fact two said "no, sorry, it's not worth my time."
I believe fiberglass batts were invented as a way contractors could cheaply insulate walls with minimally skilled labor. That was back when energy was cheap. Now it is more important to insulate supremely well and it is worth the extra expenditure to install cellulose. With more and more installers the price will likely become even more competitive and batts may end up being used by the DIY'er. At least that's my opinion.
My favorite insulation system has been BIBS (http://www.bibs.com/custom.html), but it not available everywhere and is also a specialty contractor situation. Like dense pack cellulose, a good installer will get complete coverage and fill all the voids and little spots that a batt insulation system will miss.
I did a small study once (for my book, Superinsulated Design and Construction, p. 35) where I compared the total R-value of a 2x6 wall with R-19 insulation and 12% of the wall area in framing. If batts are used and miss 6% of the coverage in voids, the total R-value of the wall is 13.53 due to framing losses and voids.
If you eliminate the voids and use the same R-value insulation (R-19), the total composite value for the wall jumps to R-17.6 (you still have the same framing losses). That is a 30% increase in overall insulation effectiveness.
If you do install batts yourself, then a really great upgrade is to add one inch or more of foamboard sheathing to either the inside or the outside of the wall. That redundant layer insulates those voids and the framing and increases the overall effectiveness by about 1-1/2 times the R-value of the foamboard.
I had a cathedral ceiling with 2x12 rafters and metal roof over sheathing to insulate-----seems to be very difficult to reach R48+ with fiberglass or other material and leave enough space for ventilation----11" of sprayed closed cell foam provided about R66+ and removed the need to ventilate the roof. It was expensive----a little over 3500 for a 24x24 12/12 roof but I think it was worth it. I would have liked to spray the walls and floor also but used R21 FG in DIY mode to manage my costs. If spray foam costs ever come down I think it will come to dominate the market.
Dirt.... a foot and a half of plain old dirt..... [waiting]
I have an insulation question/theoretical problem. If you are in a heating and cooling climate (like Ohio), lets say you frame and dry in your house with tyvec on the outside. Could you build with double staggered 2 by 4 studs:
1) Insulate the outer wall with fiberglass,
2)then put a non pearmiable vapor barrier in the middle of the two 2 by 4 walls
3) and then insulate the inner wall with fiberglass
Would you have to worry about condensation problems in such a design? Would the insulation prevent a temperature difference from causing condensation? Just trying to brainstorm a DIY method of having a sealed envelope and aviod moisture problems.
Mike, you don't want a sealed envelope or non-permiable barriers in Ohio. The walls have to breathe.
Remember that we have both heating days and cooling days so vapor needs to travel both ways through the walls.
I don't remember now where the link is, but there is a reference somewhere on this forum about vapor retarder requirements for various climates.
Don't put your house in a plastic bag.
John
QuoteIf you do install batts yourself, then a really great upgrade is to add one inch or more of foamboard sheathing to either the inside or the outside of the wall.
That's what my research has confirmed. A continuous layer of foamboard goes a long way in providing added R value.
Even before I lucked into the free Polysio sheets, I was planning on using foam board of some type on the walls and roof.
Now I have enough Polysio to do everything including the floor. I may add loose fill cellulose or something under the Polysio in the floor.
I'm trying to avoid fiberglass even though that seems to be the insulation of choice around me.
Building Science (http://www.buildingscience.com/index_html) has several great articles on vapor barriers, insulation, etc.
Their designs are specialized for various climates. You would need the vapor barrier on the inside surface.
vapor barrier (http://www.buildingscience.com/documents/information-sheets/3-water-management-and-vapor-control/info-sheet-310-vapor-control-layer-recommendations)
When I was doing insulation contracting work, mostly retrofitting old houses, we would dense pack cello in the walls then we'd do an open blow in the attic space which was generally at least two feet deep when done. If we were lucky and had exposed rafters and wall studs we'd use strapping and screw one inch Hi-R foam boards to the studs and rafters and tape the seams. Then we'd dense pack cello in the cavities. The Hi-R cuts down on the thermal bridging and also adds about R-7 to the insulation.
My preference is for high expansion extruded foam, but the cost is prohibitive for most people, including me. I've been considering building a double 2X4 wall with the studs offset for each wall. The cavities would be filled with 4 inches of Hi-R giving a total of R 56 with no thermal bridging.
Air sealing is very important as you can have an incredible amount of good insulation but several thousand CFM air movement rendering the insulation worthless.
Actually the system Mike 870 proposes would work since the vapor barrier is buried between two sets of insulated framing and will never reach the dewpoint from either side. Such a double wall system has been built in many climates and was shown (w/ slight variations) in our Superinsulation book (p. 97). It has fallen out of favor in recent years not because it doesn't work, but because it tends to be more expensive for the added R-value than things like foam sheathing and it takes up quite a bit of interior floor area.
Agree John,
For the survey... 1" foam sheathed to a r19 wall. R60 blown glass on top. Really wish the windows were better when I built. :-[
Me too!
Windows have improved a LOT! (Especially since we built in 1983!)
Guess I will chime in, since we are currently in the insulation stage. We have used R21 in the walls, and a layer of R38 with a layer of R21 in the roof trusses. I took my time and carefully fitted every piece. I am sure there are still gaps, but I bet I did a better job than if I had someone come in to do batt insulation. We have been foaming all the gaps as we go along.
I would have liked blown in or expanding foam, but due to our location no one was willing without a huge cost, if they could even reach our cabin.
Cotton Batts - easy for me to install and I hate fiberglass.
I looked at cotton batts (recycled denim) and I would bet the cost is close to spray foam!
Thanks for the info. I have read almost everything I could find online about insulation, vapor retarders, barriers etc. and it's still pretty confusing. Insulation is something I'm willing to bend the return on investment rules on. I consider it a wise hedge against fuel costs and wood chopping. If I ever get to build I'm going to do some form of advanced framing technique. There is a recent issue of fine homebuilding that covers 3 types of walls that are DIY able. It's worth checking out.
Quote from: John Raabe on December 17, 2009, 05:21:59 PM
If you do install batts yourself, then a really great upgrade is to add one inch or more of foamboard sheathing to either the inside or the outside of the wall. That redundant layer insulates those voids and the framing and increases the overall effectiveness by about 1-1/2 times the R-value of the foamboard.
Just wanted to make sure I'm reading this right. d*
I used paper faced fiberglass in my house, and it's ok to add a layer of foamboard (the pink stuff) on the inside before I drywall?
Yes, you could add a layer of that inside. Seal the seams well with tape.
I used Roxul R22 batts on the 2x6 walls and then got R30 high density fiberglass batts for the 2x10 cathedral ceiling.
That is as far as I've gotten.
I would hate to give up another cubic inch on the inside. They are getting precious.
So this rigid foam board is a vapor retarder?
Thanks Don. Is duct tape OK, or do I need the stuff that you use with Tyvek?
3M sells a Builders Sealing Tape that will work... I've seen a builder friend here using it on foam.
You could also caulk the seams with a foam compatible caulk.
Not sure about duct tape... it always seems to dry out after a few years for me.
That aluminum foil sealing tape should work too. Slower to work with as yoy have to remove the backing paper.
Quote from: John_M on December 18, 2009, 09:32:03 PM
I looked at cotton batts (recycled denim) and I would bet the cost is close to spray foam!
A quick googling looks like $.60 sq ft for r19 pink stuff and $1.10 r19 cotton. Any idea what spray foam would be?
We are building a single story 16x18 with a flat truss ceiling. I want R30 something in the attic but it seems that if I put R30 batts between the trusses I will have nothing covering the 2x4s of the trusses. My plan is to install R13 parallel/between the trusses and then lay R20 something perpendicular to them.
Sounds like it could isolate the truss chord better. What kind of trusses are you using? Open web wood? Will it be hard to get them in there?
What about blown in?
I've been thinking about this a lot for our cabin which has 6" walls and ceiling. My thoughts are:
Use 1" foam board for the exterior and 4 1/2" fiberglass inside that on the walls then use 1" foam in the ceiling stood off 1" from the sheeting with 3/1" fiberglass batting.
What are your thoughts? Will this provide better insulation then just the fiberglass batting?
I've also thought of using spray foam for any hard to reach places (like around headers or areas that are just too tough to stuff fiberglass in (becuase I've made voids by goofing up framing here and there)....
Thought I'd check in and see what was going on in here these days and first thread I find is one of my favorite subjects..insulation!
Those of you that remember me know that I'm a huge fan of Icynene spray foam insulation. First used it on a garage I built which has an apartment we lived in while building a new house. Fell in love with Icynene and used it in the new house.
One thing I didn't see mentioned much in the above thread was the technique of completely enclosing the attic area with foam where you would never do that with any other material. They spray the bottom of the roof from top to bottom and then the top of the ceiling throughout the entire house. I also sprayed under the floor (pier and beam) and all exterior walls. With foam, you get a very tight house with no air leaks anywhere. I've had the house finished about 2 years now and am very happy with low utility bills from the start.
But, I also put in an 18 SEER HVAC system and good windows.
Total cost of cooling in E TX hot summer per month...about $100 worst case. So far, heating has been under that. Figure it gives a good payback.
Okie Bob
Okie_Bob:
Ideally, one could build their whole house out of icynene. If they'd only flavor it and fortify it with vitamins, we could eat it too! haha
Merry Christmas!
Naw, Raindog, my dog wouldn't even eat it and she'll eat anything!!
Okie Bob
Foam plus?
While I am still quite a way from insulation I'm following this very closely.
Ideally I'd like to spray foam both the roof and walls. I was not intending to foam the ceiling as well.
Cost however may not permit. So other options?
What about spraying the walls with 1" of foam (to create a great seal) and then filling the cavities with batts or other insulation? (studs are 6x2). Would I need a vapor barrier? where? (I'm in mid Mississippi).
Same thing for the underside of the roof? I could spray and inch or so, put in batts, and still put foam board under the rafters.
Note also, I was thinking of using closed cell foam on the roof (for it's insulation value), and open cell foam on the walls (for it's noise dampening qualities).
Thanks...Paul
I am not a fan of fiberglass batts or loose fiberglass for that matter. I have been trying to find the quote source, but someone has pointed out that fiberglass is a common material used for filters. A good filter must be pourous which of course describes the typical fiberglass insulation batts or loose fiberglass used in attics.
Why would you want to use a filter of any thickness for insulation? ???
Something to think about and also reinforces the notion that air infiltration (pun intended :D) is a main cause of heat loss.
Some builders including Jack A. Sobon advocate the use of rigid fiberglass board which has an R-value of about 4.3 per inch.
I for one, like the idea of any "closed cell" system that is continuous, whether in the form of sprayed or rigid board.
Quote from: Okie_Bob on December 23, 2009, 07:52:49 AM
Thought I'd check in and see what was going on in here these days and first thread I find is one of my favorite subjects..insulation!
Those of you that remember me know that I'm a huge fan of Icynene spray foam insulation. First used it on a garage I built which has an apartment we lived in while building a new house. Fell in love with Icynene and used it in the new house.
One thing I didn't see mentioned much in the above thread was the technique of completely enclosing the attic area with foam where you would never do that with any other material. They spray the bottom of the roof from top to bottom and then the top of the ceiling throughout the entire house. I also sprayed under the floor (pier and beam) and all exterior walls. With foam, you get a very tight house with no air leaks anywhere. I've had the house finished about 2 years now and am very happy with low utility bills from the start.
But, I also put in an 18 SEER HVAC system and good windows.
Total cost of cooling in E TX hot summer per month...about $100 worst case. So far, heating has been under that. Figure it gives a good payback.
Okie Bob
Nice to see our resident Icynene pro checking in BoB. Great to hear from you. :)
Glenn, someone has to keep you guys in line! Or at least check in once in awhile to see how far out of line you have gotten.
I bought a boat a couple of weeks back and the guy I bought it from wants to build a cabin in New Mexico. So, naturally I recommened he check out the site. Found out later he did and says it is just what he was looking for. Unfortunately, I don't know
what name he is using but, he lives in Dallas. I told him to look out for Glenn, Mountain Don and John! So treat him nice, he's a younger guy, not like us old fogies!
Okie Bob
Without you, BoB, this forum would fly apart, so continue to check in and keep us straight once in a while. [waiting]
We'll be watching for your friend and try not to damage him. Us old timers can be a bit rough sometimes. :)
Kiwi, I like your idea of spraying the walls as it gives a great seal even if not the highest R value. But, wouldn't waste
the spray foam on the underside of your roof unless you are going to seal it completely. If you plan on a vented attic the
foam would not be the best choice.
The reason I sprayed the underside of my roof is because it is sealed with no venting at all. So, I don't even need any other insulation in what little attic I have.
If I understand your situation, I'd just go with standard ie: fiberglass, etc. Or, you could also spray just the floor of your attic and that would be great.
Okie Bob
Quote from: OlJarhead on December 23, 2009, 03:51:36 AM
I've been thinking about this a lot for our cabin which has 6" walls and ceiling. My thoughts are:
Use 1" foam board for the exterior and 4 1/2" fiberglass inside that on the walls then use 1" foam in the ceiling stood off 1" from the sheeting with 3/1" fiberglass batting.
What are your thoughts? Will this provide better insulation then just the fiberglass batting?
I've also thought of using spray foam for any hard to reach places (like around headers or areas that are just too tough to stuff fiberglass in (becuase I've made voids by goofing up framing here and there)....
Any thoughts on this? I'm in a remote location so doing anything fancy is pretty unlikely (cost prohibitive) so I'm kinda trying to decide if I do this (foam board then bats) or is I use just bats or if cellulose etc is better and I use that -- or that and foam...
All thoughts welcome
OlJarhead,
Fiberglass will allow air movement, which is why it's used for air filters and also why the manufactures are always telling people to use plastic sheeting as a vapor barrier. Also remember that the R values manufacturers quote are based on laboratory tests where the fiberglass has been installed to their exact recommendations, virtually impossible in the real world, which will have a dramatic negative impact on your R value.
Personally I would recommend the sandwich of one inch Hi-R foam boards with taped seams and then dense pack cellulose in the cavities. Cellulose will not allow any air movement and it will also fill in the entire cavity. Cellulose will give you around R-3.5 per inch, but you'll have no air leakage so it performs far better than fiberglass. If you do sandwich the Hi-R foam boards you'll want to use strapping to secure it to the studs or else when you begin dense packing it'll blow the foam boards off. I've seen sheetrock walls blow out when dense packing cellulose.
Quote from: pagancelt on December 28, 2009, 09:54:33 AM
OlJarhead,
Fiberglass will allow air movement, which is why it's used for air filters and also why the manufactures are always telling people to use plastic sheeting as a vapor barrier. Also remember that the R values manufacturers quote are based on laboratory tests where the fiberglass has been installed to their exact recommendations, virtually impossible in the real world, which will have a dramatic negative impact on your R value.
Personally I would recommend the sandwich of one inch Hi-R foam boards with taped seams and then dense pack cellulose in the cavities. Cellulose will not allow any air movement and it will also fill in the entire cavity. Cellulose will give you around R-3.5 per inch, but you'll have no air leakage so it performs far better than fiberglass. If you do sandwich the Hi-R foam boards you'll want to use strapping to secure it to the studs or else when you begin dense packing it'll blow the foam boards off. I've seen sheetrock walls blow out when dense packing cellulose.
Thanks for the great reply!
I will have to pack by hand -- does this make any difference?
So if I understood you correctly you're suggesting 1" foam board against the outer wall, tape the seems then begin packing in the cellulose and cover with 1" foam board and a vapor barrier? Or did I get that wrong?
Thanks again.
Quote from: glenn kangiser on December 23, 2009, 12:41:59 AM
Sounds like it could isolate the truss chord better. What kind of trusses are you using? Open web wood? Will it be hard to get them in there?
What about blown in?
Probably open web. I'm sure it will require a lot of trimming and fussing and hopefully I won't fall through the ceiling. [waiting]
We are fairly isolated so we will do the work ourselves. I see that you can rent the blower and do your own blown-in insulation so if I can find one of those I might try that.
I wish the spray foam was easier for DIY. We will have a metal roof and I would really like to spray but can't afford a professional crew.
Quote from: MikeOnBike on December 29, 2009, 12:36:28 AM
Probably open web. I'm sure it will require a lot of trimming and fussing and hopefully I won't fall through the ceiling. [waiting]
We are fairly isolated so we will do the work ourselves. I see that you can rent the blower and do your own blown-in insulation so if I can find one of those I might try that.
I wish the spray foam was easier for DIY. We will have a metal roof and I would really like to spray but can't afford a professional crew.
I found a Greenfiber blown-in system in the back corner of HomeDepot. The blower wants 20amps so I'll have to see if our genset can handle that.
At R-30 it is about 50 cents a sqft. I think that is fairly competitive with batt fiberglass and it should be a lot easier than trimming batts to fit.
OlJarhead,
Sorry I didn't get back to you sooner, I had the flu and was out for a while.
Pretty close. Most of what I've done is retrofitting and involved putting one inch Hi-R foam board on the inside of the stud wall using the nails with a plastic washer on the end. I then taped the seams with foil tape. After taping I'd run one inch strapping across the studs, about every sixteen inches or so, screwing through the strapping and foam into the studs. With a knife I cut a small square hole through the foam board near the floor and over any window or door, you can cut a round hole but I've found it's quicker to just cut a small square. This gives you access to the wall cavity. At this point I would take the tube for the blower and snake it up through the hole in the foam and begin dense packing. Once the cavity is done I'd stick the small piece of foam back in the hole and then foil tape it in place. Repeat on every cavity. Dry wall is then screwed to the strapping and finished as usual. Personally I see no reason why you couldn't also attach foam board to the outside of the wall using strapping and then attaching your exterior sheathing to the strapping. This would give you the sandwich of foam board filled with cellulose. Honestly I don't know how this would impact the structural integrity of the wall, perhaps John Raabe, or someone with more engineering experience then me, has some insight on this.
The problem with cellulose is, at least for a wall cavity, you cannot pack it in by hand. You'd either wet spray it in and then allow it to dry in place, or you would dense pack, as explained above. Either method requires a machine. You should be able to rent a dense packing rig. Go to youtube and search for "dense packing cellulose" and you'll find some videos showing how it's done. A lot of good stuff comes up. Also search "wet spray cellulose" to see that application.
If renting equipment is not an option, I imagine that if you also caulk the foam boards to the studs giving you a completely air sealed cavity so that if you used fiberglass it would perform far better than if you used just glass and a vapor barrier alone. In this application you would not need strapping as you would not be filling the cavities with pressurized cellulose insulation. You'd just want to use nails or screws long enough to go through your sheathing material and foam into the studs.
Hope this helps some.
Dave
Quote from: Okie_Bob on December 27, 2009, 05:44:26 PM
Kiwi, I like your idea of spraying the walls as it gives a great seal even if not the highest R value. But, wouldn't waste
the spray foam on the underside of your roof unless you are going to seal it completely. If you plan on a vented attic the
foam would not be the best choice.
The reason I sprayed the underside of my roof is because it is sealed with no venting at all. So, I don't even need any other insulation in what little attic I have.
If I understand your situation, I'd just go with standard ie: fiberglass, etc. Or, you could also spray just the floor of your attic and that would be great.
Okie Bob
Sorry for the delay in responding (I've been away working on the house). I'm planning a non vented attic. Insulation under the roof and none over the ceiling.
...Paul
Don't know if this will help anyone, but thought I'd add since it's some good info this guy has. His name is Dan Perkins and he has written many roofing article for trade mags. This particular article this link will bring you to is an article he wrote for the mag 'Journal of Light Construction'. The article title is Retrofitting an insulated cold roof (http://danperkinsroof.com/articles.htm).
I actually used this on my 3 season porch which has a cathedral ceiling. On top of my rafters I used rough cut 1' pine boards. On top of that I used ice & water shield. Then 2' poly-iso sheets (these were bought used from Insulation Depot .com, they have places all over the country that sell recycled/reused insulation board. I think I paid 9 bucks apiece. I had to buy a pallet. 80 pieces, but sold some and used rest to insulate the outside of my trailer).
I then covered the poly-iso board with 15# felt paper (in case of leaks), used 2x3 for vertical nailer boards. Then horizontal strapping that I attached my metal roof to. For the screening between the vertical nailer boards (top & bottom), I used metal screen gutter guards from Lowes, they formed easily the shape of the 2x3. I figure if I decide to heat, I can insulate between the rafters and bead board the ceiling
If this sound confusing, read the articles Dan wrote. He has great pics also. It's basically keeping the heat below and the cold above. If any one has any questions I will post some photos.
http://danperkinsroof.com/1108_JCL_Perkins_A.pdf
Very interesting article but I wonder about the weight? That's a lot of 2x4's for example and then a 2nd layer of sheeting on top of that. It would be ok on a roof framed with 2x8's or larger but what about 2x6 rafters on 2' centers?
In my case I was thinking that I could fill the 5 1/2 space between the ceiling and roof sheeting with 3 1/2 insulation and 1" foam board leaving 1" of venting.
Thoughts on that?
I did sprayed closed cell foam. Cathedral ceiling R45, walls R30. Not cheap. Of all my over budgets, this took the cake. But wow, it's very tight ie no drafts and the increase in structural rigidity is an impressive bonus. Next time I'd probably just spray the roof & do closed cell sheet foam in the walls myself for less than 1/2. If money means nothing go for it.
I'm still considering 1" foam board followed by 3 1/2" fiberglass batting then the 1" air gap, roof sheeting, 30lbs felt and tin roofing.
I'll vent each bay and finish the inside with pine boards (T&G I'm thinking).
I'll draw it out so it makes sense if my description isn't clear -- I'm mostly wondering if it's worth the money to do this versus 4 1/2 Fiberglass only?
Greetings all -
I am a newbie planning on starting to build this spring. Down here in the Ozarks we get it all, hot, cold, dry, wet. My biggest concern is dealing with moisture buildup inside the house. I spoke with the local spray foam installer, and they recommend building it tight, then using an air exchanger.
My only problem with this, besides the obvious one of expense is that I want to build as simply as possible and keep expensive to repair and replace technology out.
I would prefer to just heat with a wood stove and tough out the summers with fans....what would be my best insulation bet under those circumstances?
Doug
doug,
Still go tight and then crack a window in the winter when you want some fresh air.
(https://i998.photobucket.com/albums/af102/emcvay/Wall-1.jpg)
OK still looking for an answer here (maybe I'm just dense and didn't see it?)....
I have two options available to me (do to location, experience, knowledge, funds, and oh ya, location) so was wondering which is better.
1. As pictured: 1" foam board insulation and 4 1/2" Fiberglass batting with 6mil plastic vapor barrier
2. No foam board with 5 1/2" Fiberglass batting with 6mil vapor barrier.
My thinking was that maybe the foam board would increase the R level and cut down on air movement.
Thanks
Jarhead, I don't like the idea of foam board between the studs. You still have a thermal bridge across the studs, plus more joints for potential leaks. Plus how do you secure the foam board?
Instead of 1" board between the studs, how about 1/2" board across the face of the studs with 5 1/2" between the studs.
The effective R value is what you're looking for, not just adding up 4 1/2" of fiberglass plus 1" of foam. The thermal bridging reduces the effecive R value of the wall system.
I would use a sandwich of 1 inch Hi-R foam board on both sides of the stud wall which will give you R14 right there.
The question is first, how much insulation is required? In many ways a I agree that more insulation is better. However....
My main criticism with insetting the foam panels like that is twofold actually. 1. it is a lot of work cutting those to fit snug within the stud bay. That also will involve a lot of foam edge to stud sealing. That comes from experience on a small trial project years ago. 2. With the cost of foam the results are much better using the foam panels over the studs to break the thermal leak at the stud.
I wonder if anybody makes a paper surfaced foamboard that could be used and finished in place of drywall.
Jim
Quote from: bmafg on February 16, 2010, 03:57:07 PM
I wonder if anybody makes a paper surfaced foamboard that could be used and finished in place of drywall.
Jim
Dow manufactures a product, Thermax Heavy Duty (HD), that I believe fits the criteria. Runs about 30 bucks a sheet.
http://www.silvercote.com/PDF/ThermaxHDLit.pdf (http://www.silvercote.com/PDF/ThermaxHDLit.pdf)
Thanks all -- good points.
In truth I don't know that I need anymore then the 5 1/2 batts but it was something I've been wondering.
I suspect my actual installation won't include the foam but many topics here made me consider it -- I guess it comes down to the need more then anything.
In my case I'm less worried about winter cold as I am about summer heat -- which lead me to consider this.
So, perhaps the real benefit would be in the ceiling since it will get more direct sunlight in the summer?
Quote from: OlJarhead on February 16, 2010, 05:25:24 PM
In my case I'm less worried about winter cold as I am about summer heat -- which lead me to consider this.
So, perhaps the real benefit would be in the ceiling since it will get more direct sunlight in the summer?
Good point there. I believe any dollars and time you spend installing the highest R-value in the roof will give you the greatest comfort payback. My nearest neighbor in the mountains has a 16x24 cabin with a loft design similar to yours. In summer his cabin is always warmer (some days Hot) than ours. I think he has 2x6 rafters, maybe 2x8, and I'm not sure on how it is insulated other than he used fiberglass.
Quote from: RainDog on February 16, 2010, 05:09:59 PM
Quote from: bmafg on February 16, 2010, 03:57:07 PM
I wonder if anybody makes a paper surfaced foamboard that could be used and finished in place of drywall.
Jim
Dow manufactures a product, Thermax Heavy Duty (HD), that I believe fits the criteria. Runs about 30 bucks a sheet.
http://www.silvercote.com/PDF/ThermaxHDLit.pdf (http://www.silvercote.com/PDF/ThermaxHDLit.pdf)
This is a great thread.
Never heard of this thermax stuff. Where do you get it?
Here's my situation. I have a cabin with 2x4 walls that I will never let fiberglass touch again bcause of the mice. They love the stuff. And I don't like sheetrock. So now you have me thinking I can nail this thermax stuff on the 2x4's, fill the cavity with loose pack cellulose diy if there is such a thing. Then I can put my reclaimed barn board over the thermax.
Thoughts? Concerns?
Quote from: eggman on February 16, 2010, 08:37:46 PM
Never heard of this thermax stuff. Where do you get it?
Gee... tried looking for distributors, I'm curious myself, and this is about the best I could come up with. From Dow's "Find Answers" database:
http://dow-styrofoam.custhelp.com/cgi-bin/dow_styrofoam.cfg/php/enduser/std_alp.php?p_prod_lvl1=15&p_cat_lvl1=50 (http://dow-styrofoam.custhelp.com/cgi-bin/dow_styrofoam.cfg/php/enduser/std_alp.php?p_prod_lvl1=15&p_cat_lvl1=50)
Question
Where can I purchase THERMAX*, TUFF-R*, or other polyisocyanurate foam insulation products made by The Dow
Chemical Company?
Answer
There are hundreds of distributors across the United States for THERMAX, TUFF-R, STURDY-R, or other
polyisocyanurate foam insulation products. However, these polyisocyanurate products are not sold in Canada or
Mexico.
Call 1-866-583-2583 for information on the distributors nearest to you.
_______________
Well, guess you could call the number? Good luck, and let us know if you find a dealer, please.
Thanks for the link raindog.
Does anyone know where to get diy cellulose?
eggman,
Most lumber supply companies carry cellulose.
Quote from: pagancelt on February 17, 2010, 07:53:59 AM
eggman,
Most lumber supply companies carry cellulose.
Thanks. Do you need to have a blower? Here's my latest idea. I want to put barn board walls up and leave the top open. Then I want to hand load cellulose into the wall from the top.
Do I need sheet rock since cellulose won't burn?
The walls are 12 x 24.
You don't need sheetrock. You do want to use a blower though and you should be able to rent one from a local rental company. Go to youtube and do a search for dense packed cellulose and a whole bunch of videos should come up. It's not complex, but it can be messy and you'll get a far better pack using the blower. I would recommend using 6 mil poly on both sides of the wall if you're going to be using barn boards because this will keep the cellulose from blowing through the cracks when you dense pack. It isn't really necessary as a vapor barrier because moisture cannot transfer through dense packed cellulose. You don't need to leave the top sill open, rather you drill a hole in the sheathing, it doesn't matter if it's interior or exterior, to access the cavity and then you snake the tube up into the cavity. As the cellulose dense packs it'll back up into the tube and you pull it out a little bit, repeating this step as it backs up. You continue doing this, periodically shoving the tube back up as far as it'll go, until the cavity is completely packed. By shoving the tube up and down into the packed cavity you ensure a complete and thorough dense pack.
You can also use a sandwich of Hi-R foam board. If you use foam board you can cut your access hole through the foam, sealing the hole with some spray foam when the cavity's dense packed, and then put your siding up over that.
Lowes will lend you the blower for free if you buy a certain number of cellulose bricks. 25, maybe? Then you can return the unused packages. *wink wink* *nudge nudge*
:D
pagan
Quotebecause moisture cannot transfer through dense packed cellulose.
Are you sure about that? ???
That's what the literature states. Air cannot travel through dense packed cello so moisture has no method of movement. This link is from a manufacturer recommending against vapor barriers with cellulose.
http://www.paulseninsulation.com/docs/vaporretarder.pdf
Quote from: eggman on February 17, 2010, 08:15:20 AM
Thanks. Do you need to have a blower? Here's my latest idea. I want to put barn board walls up and leave the top open. Then I want to hand load cellulose into the wall from the top.
I personally hope you will try this scheme ... and report back on results! I've thought of giving it a try myself ...
The very top section may need some cut-to-fit sections of foam board, against the outside sheathing, to back up the cellulose.
Re: the info letter on cellulose and vapor....
I note the author is referring to "spray-applied cellulose insulation". To me that means wet blown cellulose, sprayed into open bays in new construction. I also find him a little confusing as he mentions polyethylene sheeting but talks about vapor retarders, not barriers. I think of polyethylene being a barrier, you can carry water in it. Kraft paper is a retarder, water will pass through it.
I do recall reading that a vapor retarder is usually not recommended by most manufacturers of cellulose insulation in walls. I believe this is more important when the interior spaces are air conditioned, that is cooled in summer. That was the point of that post on vapor Barriers for Dummies.
I take issue with the claim that water vapor will not pass through cellulose. In a way that might be true, but in a real world situation I believe the cellulose material will absorb the water vapor much like a piece of solid wood will absorb water from the air. At that point the water is no longer a vapor and can wick through the packed cellulose in one direction or the other depending on where the colder side is located.
In the case of a barn board wall I would recommend applying something like kraft paper or building paper before applying the boards, not polyethylene.
The machines available at my Lowe's and HD are only suitable for loose fill blow in jobs as in an attic. They do not have the smaller hoses that are required for dry blowing cellulose into wall cavities. Here thay have a 15 bag minimum to get the machine free for 24 hours.
Cellulose is treated with a fire retardant. That does not make it fire proof. It makes it burn slower and in a wall can turn the wall into a two hour firewall.
Thanks Don, what you report makes sense to me.
Speaking of insulation, I scanned the March issue of Fine Homebuilding magazine today. There is an article on zero-energy houses.
A couple of things that I noted was that all of the examples used some kind of closed cell foam, either spray or board, and one used SIP's.
No fiberglass or cellulose to be found.
Another thing noted was that a couple of them used earth based heat pumps (I may not have the terminology correct).
And lastly, none of the examples had air conditioning.
Don,
The ability of cellulose to hold embers is one reason firefighters don't care for the stuff. I've read reports where they've been called back to the same house more than once because the fire flares back up, presumably from the interior wall cavity where the cello held live embers it until they got some air. When we did weatherization work on old houses we never used vapor barriers or retarders. I've spoken with some builders who don't use cello because they say it holds moisture.
Poppy,
I've noticed the same thing regarding net zero homes. Reading about the PassivHaus movement in Germany I've seen that they're using a double stud wall with a sandwich of foam boards and dense packed cellulose in the cavities.
Found this wall system.
http://www.builditsolar.com/Projects/Conservation/MooneyWall/MooneyWall.htm
Quote from: MountainDon on February 16, 2010, 08:08:19 PM
Quote from: OlJarhead on February 16, 2010, 05:25:24 PM
In my case I'm less worried about winter cold as I am about summer heat -- which lead me to consider this.
So, perhaps the real benefit would be in the ceiling since it will get more direct sunlight in the summer?
Good point there. I believe any dollars and time you spend installing the highest R-value in the roof will give you the greatest comfort payback. My nearest neighbor in the mountains has a 16x24 cabin with a loft design similar to yours. In summer his cabin is always warmer (some days Hot) than ours. I think he has 2x6 rafters, maybe 2x8, and I'm not sure on how it is insulated other than he used fiberglass.
Interesting.
I wonder if it would be worth using reflecting (aerofoil type) insulation at the top, then the fiberglass, or perhaps the other way around....thoughts? I can try to draw up a couple ideas.
Speaking of foam, not sure if this has been posted yet. Wrap and strap;
http://sustainable.cchrc.org/docs/REMOTE_Manual.pdf
Interesting, Don_P.
I wonder if a full masonry wall wouldn't work well with this exterior wrap scheme? Would definitely move the condensation plane outside the masonry, into the insulation ... I would think.
great post don_p
I have thought about this several times and just failed to throw it out to get some intake. Closed cell spray foam to the rafter bays. For those who are doing asphalt shingles would this not cause a problem with heat buildup and longevity of the shingles. Metal roof not much of a problem but in my mind I think shingles would be a different story.
When insulating against the roof deck, shingles have to be a type that allows hot roof installation if you want to keep the warranty, or you may be able to use vent chutes.
Quote from: KWillets on February 19, 2010, 12:27:33 AM
When insulating against the roof deck, shingles have to be a type that allows hot roof installation if you want to keep the warranty, or you may be able to use vent chutes.
I'm thinking of keeping the vent as well. I have a new metal roof on top of 1x6 RS board. I wish they made long chutes.
Prior to building our small home/cabin I'm building a guest area in one end of out barn. The 10x30 area has a den, shower room and toilet room.
To insulate we applied 1/2 foam sheets to the horizontal boards of the barn to reduce the heat transfer to the interior in the summer. The foam sheets where sealed at the ends with spray foam from the small cans.
The entire guest area is framed with 2x4s on 16in centers and we added foam to the exterior side of the framing prior to adding 7/16 OSB. I now will be installing fiberglass bats with paper vapor retarder to the stud wall.
I thought about a plastic vapor barrier before putting up sheet rock but now think that I will rely on the paper.
My brother inlaw asked it I planned on heating it with a match because of my use of foam sheets.
Just got a spray foam quote back. It looks like they didn't deduct the window and fireplace sqf wall space. Does that make sense?
Also, does anyone know how to prep for spray foam install? Tape up elec boxes etc??
You just don't want a lot of dirt or crud in the wall cavity, other than that there really isn't any prep stuff, like taping around windows or electrical boxes etc. There's quite a bit of control with the spray gun.