Exterior walls – 6 inch thich outside walls –
they were the energy rage in the 80s energy crunch – what kept them from catching on (at least in the south)?
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they're still all the rage in energy star construction... but for me they don't make much sense..
the 2x6 portion of the wall is only R5.. and creates a thermal bridge.. so the cavity is insulated to R19 (+).. but the studs derate the wall..
if you go to 24 on center, then the wall loses some of it's straightness..
i prefer a Mooney wall with 2x4 @ 16" oc.. and horizontal strapping of 2x2 @ 16" OC vertical with denspak cellulose..
to each their own...
Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike
When you run your horizontal 2x2's 16"o.c. which way do you run your rock?
Vertically or horizontally?
Around here (eastern Canada), 2x6 exterior walls is required by code; energy conscious builders put 1.5" foam on the outside, eliminating the thermal bridging. In 2 storey houses, some guys go 24" oc on the second storey, but most stick with 16".
horizontally..... but the plasterer hangs his own blueboardMike Smith Rhode Island : Design / Build / Repair / Restore
I like the sound of that Mooney wall as far as energy conservation goes....but my first concern was the same as Jims....blueboard fastened 16"OC meets code? I`d also have reservations regarding the need to run plumbing and or wiring in the future.J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
what's the concern ?.. blueboard fastened to studs 16" OC.. or blueboard fastened to 2x2 16" OC...
i don't follow ..
to me 2x6 const.. doesn't make sense from an energy point of view.. all you have to do is see a picture of a thermograph of a 2x6 stud wall with R19 or R21 batts.. and you can see that it is self defeating..
the question about how to fasten INTERIOR foam ?.. we use 2# / cf density EPS and strap it with 3/4 furring ( 1x3 ).. horizontally at 16" OC.. but that will only be used in extreme cases in the future because the Mooney Wall will be our standard energy wall...
as to attics.. we spec 20" of cellulose.. depending on who's counting.. that's either R60 or R74..Mike Smith Rhode Island : Design / Build / Repair / Restore
Sorry...didn`t word that well. As I understand, drywall, blueboard, CB, etc. need to be installed perpendicular to framing and fastened as such. Perhaps I`m mistaken.J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
i don't think so.. it's not structural in most instances..
and of course.. this locale traditionally furrs our ceilings.. and the gypsum is hung either way.... with the furring or across the furring
but hey, whadda i no ?Mike Smith Rhode Island : Design / Build / Repair / Restore
"As I understand, drywall, blueboard, CB, etc. need to be installed perpendicular to framing and fastened as such. Perhaps I`m mistaken."
Well, you're absolutely right that that IS the traditional method, Jaybird. But I think it has more to do with minimizing shadow lines caused by mud filled drywall joints in a person's normal line of sight. Now, if you were to crane your neck against your baseboard and look up along a stairwell wall, you'd probably see shadowlines similar to what you'd see in a house with the drywall hung vertically (you might get some odd looks from the inlaws, too).
Thanks for the confirmation Jim....Along with minimizing the run of uninterupted joints for visual improvements, I`ve also always felt that what structural integrity drywall (wall surfaces in general) may posess, as minimal as that may be, was acheived only when installed perpendicular to framing, as well as the staggering of joints.
However, this strength may be acheived by the use of the firring strips themselves now that I think about it.J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
Mike:
OK, I guess I'm a little dense, but would you mind fully explaining this "Mooney wall " thing. Like maybe exactly what is is composed of from interior finish, each layer to the exterior finish. I did a google and came up with nothing. Maybe you explained it in another thread, that I did not read... Is the cels the blow behind mesh kind or the wet kind... just trying to learn something here.
And sorry I gotta ask: where did the name "Mooney wall" come from? Some guys hanging around the airport with weird haircuts...!?
Thanks,Matt
my wall... designed here on BT... named it after Tim Mooney..
ever remember "The Right Stuff".. how they were always talking about "elegant solutions"... or how to get a space module back from the moon..... and they decided to start throwing things away ?
well... i was building energy walls with dens-pak cells and 1" EPS on the interior.. and then furring the walls with 1x3 furring... Tim asked some fateful questions and started me thinking...
with the foam i was gaining a nice thermal break, but it was only about an R5..
plus i had to special order the EPS, pick it up.. blah, blah , blah..
what we arrrived at was that by furring the walls with 2x4's ripped in half,, we wre gaining an inch & a half (R5.5) .. we were getting a good thermal break because we had reduced the contact bridge to 1.5 x 2 every 16"..
we were moving the electrical devices out from the sheathing 1.5 " so we vould get good dens-pak BEHIND them.. and we could either blow the cells into a Regal wall mesh... or drill 2" holes in the blueboard and blow thru the gypsum..
anyways ... the pluses outweighed the minusues... and i adopted the Mooney Wall as our standard energy wall..
here's the last of the dinosaurs....
Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
I assume blocking for cabinets and such takes the same forsight as it would with verticle studs. You probably run 2x4 & 2x6 instead of 2x2 where blocking is required. No?
I've got to tell you though, this system would throw me for a loop on a remodel job, if i didn't know it was there. When installing anything wall mounted on a traditional wall, even if there is no blocking, you know that you can find a stud at any hight, every 16".
But with the "Mooney" wall, I could see myself going nuts trying to find a stud in the area between the strapping. And after I would figure it out, what do I do to get something to screw off to at a hight other than the location of the strapping?
John Svenson, Builder, Remodeler, NE Ohio (Formerly posted as JRS)
sven... one of the things i figgered is... this is ONLY the exterior walls...
and a resourceful scede like you would come up with something..
besides... whadda ya do when that ONE cabinet misses a conventional stud ?
you come up with something.... that's why you get the big bucks.. hah, hah hahMike Smith Rhode Island : Design / Build / Repair / Restore
Thanks for the explanation. For the price, undoubtedly, the reduction in thermal bridging is unsurpassed. I can see that your method would likely outperform a 2x6 wall.Matt
yeah... and we owe it all to tim... god bless us, everyone of us !Mike Smith Rhode Island : Design / Build / Repair / Restore
OK, how about the 6" wall that was framed by alternating 2x4s on 12" centers between the outside and inside of the mudsill? The idea being that you would not have the thermal breaks from a 2x6 and would have room for 6" of insulation. How much worse to frame was this type of construction than normal framed walls? What is the name for this type of construction?
staggered studs.. good wall.... bet it's harder ( read "more expensive" ) than a Mooney Wall
our house has a similar wall
2x4 exterior..1" airspace... 2x3 interior... too bad it was before my straight cellulose days.. Mike Smith Rhode Island : Design / Build / Repair / Restore
Back about the time that I built my house (1979) I went to a home show.
I remembered that someone was selling a system that used foam modules that had slots in it. They alternated on each side. I don't remember the details, but I probably used 2*4's on 6" plates.
So you ended up with something like this 0 - FOAM X- STUDS
OOOOOXOOOOOXOOOOOOX
OOOOOOOOOOOOOOOOOOO
OOOXOOOOXOOOOOXOOOO
Similar to this:
http://www.truefoam.com/insulwall.html
The best that I remember the details where much different, but a similar concept.
Of course you have to remember that was over a century ago in dog years.
2x4's ripped in half.....god god, give me SIPs.....
Mike,
Regarding thermal bridging- I'm assuming that means there's less than R-19 where a stud is because the wood is not as good an insulator as the fiberglass. In that case, anywall constructed with studs will have thermal bridging, right? Overall though, the 2x6 with R-19 would give you better performance than 2x4 with R-13.
Disregard- I just saw your picture- all clear to me now.
Brian
Edited 12/11/2003 2:17:00 PM ET by stonebm
Hi all
Great timing on this discussion. I have a potential client that wants super insulation and is even considering straw bales. I hope to convince them that 2x6+foam, staggered stud or Mooney wall (new to me) are better choices. Virtually all construction here (Eastern Maine) is 2x6, R-38 cielings, foam sandwich headers and exterior insulated foundations.
Thanks for the Mooney wall tip, wk
hey tim... see dat ... tole you i'd make you famous.........
The Mooney WallMike Smith Rhode Island : Design / Build / Repair / Restore
Here is some web sites with some related info:
Another opinion on 2x4 vx 2x6 walls:
http://www.advancedenergy.org/buildings/publications/on_the_house/onhs211.html
And this one talks about thermal bridging and has an infared picture that illustrates it:
http://www.foam-tech.com/theory/thermal_break.htm
Both of these sites have a bunch of energy related articles, although the second one might be slanted tward the product(s)(?) they are selling.
Matt
It's all got to do with money - is it a good investment for your climate, and what is the amount of time to get the payback? Somebody came up with a formula that says that if your area has a certain number of heating degree days then 2x6 walls are a good investment. Look at this web page: http://www.askthebuilder.com/BT_2x4_vs_2x6.shtml
Then look at this document, and use the search function on your Adobe Acrobat .pdf viewer (the binoculars) to find the US city nearest you. You will be looking at the 65 degree column:
http://www5.ncdc.noaa.gov/climatenormals/clim81_supp/CLIM81_Sup_02.pdf
What I don't understand is why cooling degree days don't figure into the formula too...
Well, here in the temperate Pacific Northwest we have pretty strict energy codes, and unless you go to minimum glazing and heat with gas and get real high "R" values in your ceilings you have to have r-19 in all exterior walls. Now, I guess you could achieve that in a 2x4 framed wall, but I think it would be more expensive than framing walls with 2x6. Haven't seen a new house, or addition framed with 2x4 walls in the 20 some years I've been building out here.
Hey Mike - what kind or "R" values do you get with that wall you described? Don't I remember you saying something about adding insulating board to the exterior surface of your 2x4 walls a couple years ago instead of framing with 2x6?
You guys who DO add a layer of insulating board, how the heck do you nail your exterior trim and siding? That system must affect which type sidings you use most often, doesn't it? Hard to imagine using sidewall shingles, for example. Do tell.
House next door has foamboard, then strapping, then hardiplank.
Used 1" insul board on 2x4 walls with 1 5/8" SS screws to hang certainteed perfection shingles and 3 1/2" trim lineals. No problems...can adjust easily, won't pull loose and no fur strips.
jim, i think it's a true R17...... with almost no thermal bridge...
when we USED to use foam on the exterior... it was 1".. and we used 1" blocking at teh sills, plates corners and openings.. then 1/2" sheathing , so we could have any kind of siding we wanted..
i've also done 1" foam on the interior, with 3/4 strapping horizontally.. that was about an R18...
and we've done 2x4 exterior wall, 1" airspace and 2x3 interior wall... but i think the Mooney wall is the best of the bunchMike Smith Rhode Island : Design / Build / Repair / Restore
I'll be doing something like this soon and would like to know how the foamboard is usually attached. Glued, mechanically fastened, both?
Thanks.
Thon
Nailed, with washers about 1.5 inch diameter. Either plastic washers, or those sheet metal ones. (Sorry for the non-technical terminology).
That's interesting (R-19 is standard). We rarely see it around here. So, what is the standard r-value in your area for ceilings and also floors over crawl spaces? (assuming a vented crawl) Or is unvented the norm...?
Matt
I got a notice in...I think it was July...that the energy codes had just been tightened up again (especially regarding "U" values for glazing) but I haven't pulled a permit since then so I'm not sure about the exact "R" value requirements these days, Dirishinme, but I'm pretty sure the prescriptive requirement is R-30 in the floor over an unheated crawlspace (normal around here) and R-38 in a flat ceiling.
But all I've pulled permits for these past 20 years are remodels and additions, and we always get into "existing space" situations - you know, the inspector stands there and says "well, you filled the space, and they did a nice job", or something like that (our local inspectors take one look at the sprayed in fiberglass I like to use and reach for the permit to sign off, that stuff is GREAT). The two counties I work most often in always give a pretty thourough checklist with the approved permit that has a scale on it that shows if you fall below certain wall thickness, you have to make up for it with less glazing, or thicker ceiling insulation etc.
I'm astonished to hear about all these cold climate areas with people still building 2x4 in the name of saving money. What would it cost, a few hundred, maybe a thousand bucks to go to 2x6? You'd spend that quick enough adding all this strapping and blocking, or in heat bills, wouldn't you? Now, if you're saying it makes for a "better" wall, with less thermal bridging like Mike says, there's some logic to that. But in the name of "saving money"? I'm a little confused about that one.
Hi Jim. King and Snohomish county (maybe the whole state) require r-21 wall insulation now. I was in Home depot the other day, they dont sell r-19 anymore, just r-21 (at twice the price of course). Is that sprayed in FG you use what they call BIBB? Chopped fiberglass blown in behind a netting material? Do you do it yourself?
I like Mikes wall with the horizontal strapping, very little thermal bridging there.
Sometimes I wonder how much difference the wall r-value really makes, if its r13 or r20+. When you figure in window and doors, total wall r-value must be pretty low. I think if you airseal all penetrations carefully, use energy efficient windows and doors and insulate the heck out of the ceiling and floor and ducts, you're doing pretty well.
Hey yourself, Jimbo. You still living the dream?
"Is that sprayed in FG you use what they call BIBB? Chopped fiberglass blown in behind a netting material? Do you do it yourself?"
Yeah, I think the acronym stands for "Blown In Blanket Sysytem" - "BIBS". I hire it done by Carrig & Dancer Insulation Company in Olympia. I think they might hold the regional franchise for it, but I'm not sure. And yes, they first staple a blue netlike membrane, might be about 1/8" mesh, onto the face of the framing, cut a hole in each stud bay and blow it through about a 2" hose.
Have you seen it? GREAT for remodelling. I'm not going back to batts anytime soon, I'll tell you that. You walk into a house after it's been sprayed and can almost feel the difference in the way the air moves. Totally deadens sound transmission. Very impressive stuff, and not that much more expensive than batts...I think last job was 15% more, or something.
You guys can have your cellulose. I have seen the insulating savior for our climate here in the Puget Sound region and she's named BIBS.
By the way, thinking about Carrig and Dancer - they were the first people I ever saw use those Italian pnumatic staplers to affix that netting. Have you seen those? I guess they are really upholstry tools, but they have a dial on them to adjust how many staples come out per second. These guys just dial the knob up, pull the trigger and as fast as they can drag their hand down the length of a stud this thing fires staples - like a fully automatic rifle. Unreal the first time you see it. They come out so fast you hear one constant sound instead of each staple being driven individually. I gotta believe they are illegal according to OSHA, but man, they can drive some staples in a hurry. Small tool, about the size of the old Senco pin nailers. You seen them?
Yes Jimbo, still livin the dream. But if I don't get my contractor business going strong by the time my part-time computer job ends in about 2 years, it could turn into a nightmare. Got 3 kids entering college in the next 4 years. yada yada yada.
I have seen the BIBS system with the netting in one of my previous houses. Mike Smith has an issue with the cellulose getting between the stud and the netting when densepacking it in so he smears glue over the stud/netting to stop the problem. So that isnt an issue with BIBS?
Sounds like maybe that Italian stapler youre describing is made by UZI?
My local lumberyard in Monroe sells bales of chopped FG and lets you use their blower for free.
happy holidays to you and yours
I worked on Habitat for Humanity in Montana, and I'm pretty sure they skinned it like normal, then added the foamboard with fasteners with big plastic washers (Quite colorful, actually. Think I've seen people use similar one with the roofing paper). Then they just attached the siding through the foam. I'm not positive, but I think that's how they went about it.
hey.. i thought i'd resurrect this thread since someone linked to it..
here's a pic . of typical thermal bridging as shown in a thermogram
View Image
you can clearly see the cold studs lurking behind the drywall surface..
thermographs are cool..
some of the ones i've seen of the exterior of homes will just knock your socks off
'course ... on certain frosty mornings you can see this with the frost still in place at the insulated wall section.. but melted off each of the studs from the heat lossMike Smith Rhode Island : Design / Build / Repair / Restore
Ei yi yi, I'm very interested in eliminating thermal bridging, because (but of course) I like building houses with a lot of glazing, but I'd like them to be as inexpensive as possible to operate, ha, ha,ha. Hey, every little bit helps<G>I can't seem to get a wrap on your( dang, I mean Tim's) system. Could you post a cross section I could steal? No, really, Rick Arnold wrapped his place in some foam board on both the outside and inside( if I got it right), but put solid stuff exteriorly around doors and windows for trim, which to me = bridging. I see you have what looks like styro board between interior furring...looks like it takes some time + what's up around window/door penetrations?And, I know I'm probably misfiguring this, but with a 2x4 and a a2x2 I get 5", how do you order your door and window jambs? Special orders?Sorry if I'm being extra thick, but that is my specialty<G> Don't worry, we can fix that later!
snort....
5" + plywood + drywall + 6" so we order doors with 6" jambs.. not an unusual item..
even if they come thru 6 5/8... not a big problem
or depending on the door ( center-swing patio door fer instance) we order a common 4 5/8 and use jamb extensions or wrap the plaster
don't confuse our olde energy wall with our Mooney Wall
the old one had 1" EPS on the interior and 1x3 furring .. no blocking
the mooney is just a 2x2 @ 16" horizontal
then we use insulmesh and blow it with dens-pak cells..
one feature of Mooney.. it's labor intensive.. so for a DIY , it's great.. but i have to watch out that maybe gun foam may be more cost effective.. but i doubt it.. thoise guys get huge $$$$$ for spray foamMike Smith Rhode Island : Design / Build / Repair / Restore
Sorry you guys, the Mooney wall still isn't googling. As we all know, if it aint in Google, it doesn't exist.
How bout a nice diagram of this Mooney wall design for posterity? The whole wall from drywall to exterior siding (assume clapboard) I'm not a pro; just a DIYer and, as they say, a picture is worth ...
If you don't have web space, email me a jpg and I'll put it on my siteand post the URL here. My bet is that once this diagram goes up, people will have some interesting enhancements to this.
My building department won't issue a permit unless you're framing with 2x6s. But it gets real cold here in winter.
You don't say what art of the country you're from. But here in Illinois, I'd say people don't do it because of cost.
Using 2X6 walls obviously costs more, and people just aren't willing to pay the difference.
I'm wearing my Burger King underwear... the home of the whopper.