Super-insulated walls, double 2X4s
Hudson Valley Carpenter
| Posted in Construction Techniques on
Several of us spent some time here on BT a while back, talking about various methods of building super-insulated walls using dimensional lumber.
It was enlightening for me to hear from Mike Smith and others about the Mooney wall system, standard 2X4 framing with 2X2 horizontal strapping on the interior side, insulated with dense-pack cellulose We discussed pushing the Mooney wall dimensions out from 2X4 to 2X8, in order to achieve super-insulation numbers.
We also talked briefly about framing two exterior walls, inner and outer, with 2X4s.
I’d appreciate hearing pros and cons from those who have experience with double 2X4 walls, both building them and living with them.
Thanks for your time.
Replies
When he was still around Riversong sent me a link to a thread which had a good description with pictures of the double walls he built. I think it was in the Green building forum. He didn't include a very reasoned pro and con discussion though...
What I liked about the way he was doing it was that the inner wall was loadbearing so that the outer one ran uninterrupted outside the rim joist, eliminating the complications that usually occur at the second floor level.
I remember looking at photos Riversong posted, showing that wall design. From a framer's point of view, it looked like a clusterhump of major proportions. Just too much labor unless you have a lot of volunteer help to get 'er done. As I recall, Riversong was running a DIYer's school when he built those homes, which may have allowed him to put his students to work, as a class project.
In any case, the Mooney Wall became my main focus after that. But when I ran some numbers yesterday, I saw that if I used 2X8s to achieve enough depth for super-insulation, the cost for my next project would be $500+ more than a double 2X4 wall.
Using a double 2X4 system, leaving a space between them as a thermal break, would eliminate the 2X2 strapping used on Mooney walls. That's a feature of the Mooney wall which requires ripping culled 2Xs, then striking lines and nailing them up.
Trying to imagine the time required to do those steps, it seems to me that it might be roughly comparable to framing a second, unsheathed 2X4 wall. Even if the time difference was more than that, the money saved by building with 2X4s instead of 2X8s would easily cover labor cost.
So that's how I arrived at this double 2X4 super-insulated wall question once again. On paper it makes good sense. But it's possible to make lots of design ideas look good on paper. That's where the knowledge and experience of the BT community comes in.
Edited 7/30/2009 5:14 am by Hudson Valley Carpenter
Here's a modified 2x8 wall.
Our house built into the hillside at the rear. Plenty of glass to the south (downhill side).
So as not to have a ledge either in/out I used 2x8's for the wall atop the 8'' block (stepped). Let in bracing and a Canadian idea at the time-sheeted w/ 1''Dowboard, then vertical furring to catch the siding with felt over the furring. Block had 2'' rigid fibreglass (Warm and Dry) to insulate and facilitate drainage. 3/4'' foam on the interior of the block.
Stud spaces insulated w/fibreglass batts, now I'd have used something else. In the 80's didn't know diddly about anything else but decomposing foam and blown attics.
With the stepsA Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
I can't see how the 2x8 wall is MORE costly than a doubled 2x4 wall.
With the 2x8. you frame one wall once, but with the 2x4 x 2 you have to frame the entire exterior twice. That is a fair amt of labour.The 2x8 is more expensive lumber by a small amt, but surely not enough more to beat up that labor cost by 500 smackers
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I can't see how the 2x8 wall is MORE costly than a doubled 2x4 wall.
The comparison is: 2X8 Mooney wall...with 2X2 strapping for thermal break vs double 2X4 wall spaced for thermal break.
Here's what got my attention yesterday. 2X8-8'=$5.58, 2X4 precuts=$1.97.
My next project will need about about 350 exterior wall studs if using 2X8s. Can't get precut 2X8s, unless it's a special order so there's some additional labor.
Framing with 2x8 plates and studs is going to add time to the process vs 2X4's. Ripping 2X culls for strapping and then nailing them up, quite a bit more labor.
I can figure, pretty close, how much time it would take to layout and frame an unsheathed wall. I don't believe that it would be a lot more time than the additional work associated with a 2X8 Mooney Wall.
In any case, I'm trying to get past the hypotheticals here and see what those with first hand experience have to offer.
Edited 7/30/2009 3:04 pm by Hudson Valley Carpenter
It's funny what time does. I went back and looked at Riversong's system and found it was quite a bit more complicated than I remembered. What I remembered it being was the way I think I would build it.
I would frame the entire house conventionally with 2"x4" walls. The only modification being that the sills were set in 3 1/2". I would then frame an exterior 2"x4" wall continuous from sill to roof. This wall would be framed against and be attached to the second floor rim joist, with fire blocking between the studs at the floor level. The outer wall being attached and blocked this way means it could be loadbearing picking up the roof, and the exterior sheathing would now provide effective shear resistance.
Do you think this makes sense?
(edit: I have no idea why I'm suddenly posting in italics)
Edited 7/30/2009 12:07 pm ET by fingersandtoes
Do you think this makes sense?
Nope. Much simpler, quicker and easier to lay out, frame and sheath the exterior wall on the new floor, then raise it. Next frame and raise the inner wall in the same way.
Suggest you read Marson's earlier post. Let us know if anything sticks out as a problem in his description.
Edited 7/30/2009 3:06 pm by Hudson Valley Carpenter
Considering that all you gain is eliminating the thermal bridging at the second floor it does seem like a lot more work. I'd do it Marson's way.
Considering that all you gain is eliminating the thermal bridging at the second floor it does seem like a lot more work.
That exposed rim joist seems like a big deal but when the adjacent inner cavity is filled with superior insulation it's not a serious problem.
Speaking of avoiding thermal bridging...one of the things that attracts me to the double 2X4 wall is the minimal bridging around window and door openings.
The Mooney wall doesn't avoid bridging next to openings as well as the double 2X4 wall because its strapping must encircle the opening to provide nailing for dry wall and trim. I don't know how significant that is but it's not on the plus side.
I also prefer the bridging being interrupted in the middle of the insulated cavity, rather than so far to the inside, as is the case with strapping. It just seems to be a more effective way to stop the cold from penetrating into the living space.
Edited 7/30/2009 3:15 pm by Hudson Valley Carpenter
Good points. Have you given much thought to the inner wall? Single top plate? 24" o.c. instead of 16"?
To help with the rim joist problem, I framed my own house so that it was inset 1 1/2" and put foam board on the exterior behind the sheathing. That is where my carpenter ants set up shop. They (and much of my foam) are now gone. I'd never do that again - well certainly not here in the rainforest.
Thanks for telling me about the carpenter ants in that cavity. We have them in NY State too, in abundance, so I'll keep that in mind.
Have you given much thought to the inner wall? Single top plate? 24" o.c. instead of 16"?
Not as yet. I've only just switched my thinking to this method so I haven't worked out the details.
What makes sense to me, at the moment, is typical double top plates because it's still necessary to lap them at intersections and in corners, for strength.
In addition, using precut studs as a time saver makes standard framing the necessary choice.
I don't see any advantage in using 24" centers in this case either.
I built a double walled house once. My approach was to frame the house conventionally out of 2x4's. Then, I stood a second wall up on the inside. The window framing RO's were oversized so that I could insert a box made of plywood the full wall width. The rim joists were spray foamed, but otherwise it was dense packed.
It really went pretty smoothly. Riversong's method is interesting, but the flaw I see is the amount of labor to set up scaffolding and frame this second skin from the exterior. My AHJ would also require something like that to be engineered since he doesn't have plywood on the load bearing wall.
The above mentioned house performs wonderfully. The owner calculated his natural gas usage and it was jaw droppingly low (and we live in a climate with about 10000 heating degree days).
If I'm not mistaken, the studs for Riversong's exterior wall, with plywood gussets preattached, were erected from inside the house, simply reaching through the inner wall studs, placing the outer stud, and nailing off the gussets to the inner studs. External sheathing, with diagonally nailed boards, of course would have to be done from the outside. The pictures referred to are posted on the BuildItSolar.com site [edit:] http://www.builditsolar.com/Projects/SolarHomes/LarsenTruss/LarsenTruss.htmAlso, the gussets are said to be rough sawn 1x4, not plywood.
Edited 7/30/2009 8:54 am ET by DickRussell
In 1983 we built a house with foot thick walls. outside standard 2x4 construction. 12" ply for the plates and another 2x 4 wall inside. Sparkies loved it.
No rim jiost between upper and lower floors. Top chord truss suspended from the inner 2x4 wall, so there was no breaks in the thermal skin. A friend was just taking his R 2000 training and we did a blower test with trace gas. less than 1/2 air change an hour. I was anal about sealing every thing and used more acustical snoot than needed.Lived there 13 years and it was way warm only needed a 55,000 BTU furnace to heat it. and the gas bills were low. Of course we put a HVAC system in.The window wells were ply.
Thanks Marson,
That confirms what I've been imagining about that method, pretty simple with lots of benefits.
I appreciate the tip about joining the openings with a plywood skin. Another simple solution which fulfills all the requirements. Did you do the same thing at the top plate?
What spacing did you use between the inner and outer walls? Did you use that as a chase for the wiring?
Seen this?
http://www.jlconline.com/cgi-bin/jlconline.storefront/4a71bf5316fb4b6727170a32100a0661/Product/View/0906buil
Thanks but I ain't payin'.
I don't have the digital access either or I'd send it your way. All I remember at the moment is that they used double, offset, 2x4s and also double framed the rafters using using strips of scrap sheathing to hang the inside 2x4s.
Wait ... I just googled a freebie! Here ya go:
http://www.kaplanthompson.com/_images/publications/09.06-jlc.pdf
Wait ... I just googled a freebie! Here ya go:
Thanks but the link didn't produce. Probably a copywrite violation to do an end run like that.
Edited 7/30/2009 12:39 pm by Hudson Valley Carpenter
Now dadgummit that's frustrating.
Well if the archy's site didn't produce, how about the builder's:
http://kolbertbuilding.com/images/stories/maclehose_hayden/0509jlcmachay.pdf
You probably won't think it is worth all these trys, but I can't stand to not follow through so do me a favor and try one more time. And if that don't work, you can gimme your email and I'll send you what I just downloaded.
Edited 7/30/2009 1:26 pm ET by Righty_Tighty
I appreciate your interest in the topic and in making that article available. It's a PDF file so that may be the problem. My computer doesn't always get along well with them.
I've tried both links a couple of times, refreshing each as well. Nothing appeared, including the hour glass or any of the usual "loading" signs.
You can copy and paste the text in an Email to me, if you wish. I would like to read it. Just click on my screen name, then "send Email".
Thanks, Peter
I wrote the JLC article. E-mail me if you want a copy.I think Riversong's methods are very cool but I also think they rely on relatively cheap labor - my sense is he has a lot of homeowner involvement.The rim joist is definitely an area of concern for us as well.
Well, you can't beat that response.
Enjoyed the article and your website Dan.
Hey, thanks for being so persistent in your efforts to share that article with me. There's a lot to be learned from Dan and that house.
The rim joist is definitely an area of concern for us as well.
I've considered that problem too, every time I get on this super-insulation track.
I've thought about using two rim joists, an inner and outer, to stop thermal bridging but the outer joist needs to be held vertical under various loads. That suggests blocking would be necessary so I'm right back to a bridging problem again.
So, how about this? Make a sandwich of the inner and outer rim joists with XPS or other dense foam insulation in the middle, then bolt them together at wide intervals with blocking adjacent to each bolt or pair of bolts.
How about this between floors:
Comments solicited, if you please.
That assumes your interior wall is bearing. And the exterior wall is looking pretty tall, esp. if the roof load sits on it - looks like it would scissor at the break.My insulators brought their webbing up between the joists and dense-packed the bays to the depth of the walls. Our thermal scans didn't show any difference in the rim than elsewhere, so it may not be as big a problem as we all think it will, esp. if your air-sealing is good.
That detail is similar to what I was suggesting but once both the outer and inner walls are loadbearing you have the problem of needing headers on both walls at openings, and also providing bearing for the inner wall on the foundation.
Considering the benefits you have already gained by going to a double wall, and taking into account that the major losses will be through the windows and doors, probably the small area of thermal bridging at the second floor is not of that great a consequence.
probably the small area of thermal bridging at the second floor is not of that great a consequence.
I agree. IMO, rim joists look like a larger heat loss problem than they really are. A rim joist is really nothing more than part of the exterior skin, except that the floor joists which are fastened to it create a path for thermal bridging/heat loss. If I-beam joists are used, the area of bridging isn't all that significant.
Using a deep joist cavity over a deep exterior wall, both insulated to a high R-value, I expect that heat loss through the rim joist is easily acceptable when compared with the amount of time and effort it would take to lower it further.
How about this between floors:Comments solicited, if you please.
It's a neat, economical idea, eliminating thermal bridging via the rim joist while tying the two walls together with the plywood subfloor.
I expect that if you use trusses for the roof, thereby making the inner wall the major bearing wall, it would work OK. That's if it bears fully on the foundation.
A couple of things that the engineer might not like; the outer 2X4 wall is going to need 2X4's about 9' long, and the inner bearing wall will need to be permanently braced.
Honestly, if it were my idea I'd want to try it. But, at this point, I'm satisfied with the more pragmatic choice, following standard framing practices and adding an inner non-bearing wall.
As previously noted, after due consideration I'm now of the opinion that the rim joist heat loss problem can be dealt with effectively without isolating it from the outer skin.
Edited 7/31/2009 5:48 pm by Hudson Valley Carpenter
The other thing that the designs using continuous exterior studs or at least an exterior wall not interrupted by the second floor don't take into account is the differential shrinkage that will occur between the two walls.
differential shrinkage.
Never been a problem for me. Occasional warpage...that's another story.
I like your second floor detail with the rim joist on the interior wall and no Larsen truss on the outside. I would like to upgrade it to an LVL rim and not use any built up headers over openings.What were you thinking at the foundation?Slab on grade build and tilt both walls one at a time. But on basement ICF or cement block, using the same detail for the floor framing, the outside wall couldn't be built on the floor.At the roof just set the trusses on ply tying the two walls together.Were you thinking of setting your windows to the exterior plane?Ply box back to interior w/ room for foam bd under the drywall returns and solid surface or laminate sills.
That .pdf showing detail between floors came from a set of sketches I have posted before. They are based on ideas derived in part from early work by Gene Leger (late 70s-early 80s) and from Riversong's modified Larson truss. Attached is the .pdf for the detail at the foundation. The sill (in this version) hangs out over the 2" exterior XPS, so the outside of the studs do as well. Inner wall is bearing floor and roof loads, so the outer wall holds up only itself and the windows. In this regard it is similar to the Larson truss.The other way of doing this would be to make the outer wall with 2x6 and have it bear at least the roof load.Riversong uses a full width, rough locally cut sill. Since the BI wants to see PT on the foundation, despite the fact that sill sealer isolates it from the concrete, I drew the split sill in the sketch. I know, it doubles the sill effort.Building on a slab eliminates a lot of the load bearing issues. Load bearing can be on either outer or inner wall.As to bracing of the inner stud wall if it bears all the loads, but the sheathing is on the exterior wall, I have a question. Is it structurally correct that the continuous plywood connecting the tops of the inner and outer walls would transfer all lateral loads between those walls and thus not require bracing at the inner wall itself? In other words, if the outer wall cannot rack from wind or other forces, how could the inner wall if it is attached continuously at the wall tops? Educate me. I don't mind being wrong; I just want to understand why.
The .pdf attachment didn't show up??? Try again:Ah, I forgot to click "Upload."
Is it structurally correct that the continuous plywood connecting the tops of the inner and outer walls would transfer all lateral loads between those walls and thus not require bracing at the inner wall itself?
It's a big benefit and probably would do the job by itself but the plywood subfloor is in another plane so the engineer is likely to want let-in bracing on the inner wall.
It's not a big deal to install such braces, just a saw kerf cut along a chaulk line snapped on a 45 across the face of the studs as the wall lays on the deck.
One of the problems with being an innovator these days is finding an engineer who is willing approve structural items which are non-standard. That's part of the reason why I said previously that I'd stick with standard framing for a double 2X4 wall.
Keep it simple, get it approved, make it easy to lay out and build. There are enough headaches in getting a custom home built within the budget and time constraints. If I can solve a potential problem beforehand, that's the way I'm likely to go.
In the old days, when a visit with the building inspector, a couple of DIY drawings and a check for $100 was enough for a carpenter to build a new custom home of his own design, I didn't think twice about trying new methods or inventing my own practical solutions to potential structural problems. But that scenario is laughable now, since the lawyers have made even the smallest town government afraid to color outside the legal lines.
Edited 8/1/2009 11:18 am by Hudson Valley Carpenter
"It's a big benefit and probably would do the job by itself but the plywood subfloor is in another plane so the engineer is likely to want let-in bracing on the inner wall."In the first sketch, showing wall connection between levels, the subfloor runs out to the outer wall. Why wouldn't the floor be braced laterally by the outer wall?
In the first sketch, showing wall connection between levels, the subfloor runs out to the outer wall. Why wouldn't the floor be braced laterally by the outer wall?
That's what I was referring to, the subfloor connection. It's in a different plane, perpendicular to the potential loads on the inner bearing wall so it might not be cool with the engineer.
Like I said, I like the concept and I wouldn't object. As long as everything is well fastened, it should do the job fine, but it's still non-standard for a bearing wall.
You could easily provide shear for the inner wall by sheathing each corner with ply. I don't see that it would interfere with anything.
interesting thread.
It's not a big deal to install such braces, just a saw kerf cut along a chaulk line snapped on a 45 across the face of the studs
We always laid the brace across the wall, in place. Set your circular saw blade depth to 1 1/2", and set the base on top of the brace, with the blade aligned with the edge. Standing on the brace, cut the length of the brace along one edge, then go back the other way cutting the other edge. Then...
Oh, wait. You're using the L-metal straps. One saw kerf. Never mind.View Image bakersfieldremodel.com
interesting thread.
Indeed. Dancing Dan's article is a real eye opener and others have contributed some useful knowledge and experience too.
How did that picket fence turn out? Did you add more photos to that thread when you'd finished the job? Some threads get knocked off the front page too quickly.
Thanks. Here is the finished photoView Image bakersfieldremodel.com
Thanks for the link. That's a beautiful job, the entire package. I really enjoy creating things like that gate. Too bad you can't charge what it's worth but at least you'll get to see it from time to time, being down the street from your mother's place.
The street number and the style of the house got me thinkin' it's in NoHo somewhere. Am I close?
Absolutely. One block from the Burbank border, near the old railroad tracks now a walking trail.
By the way, I've always thought a double 2x4 wall would be the logical choice for a superinsulated thermal break wall. When you get into framing with wider members, 2x6, 2x8, or whatever, there is a whole different dynamic to the framing process that increases the labor involved. 2x4's are lighter, easier to work with, easier to straighten out, easier and safer to stand the walls, easier to find in clean straight pieces with no checking or bark, etc.View Image bakersfieldremodel.com
You've hit a lot of key points in the comparison.
I'm very pleased with what I've learned from those who shared their experiences on this topic. It all adds up to a winning combination for me.
It was certainly our experience that double 2x4 was pretty simple. Raising all those light walls made my crew's aging backs much happier.
I thought that was how you would detail for a basement.Personally I like the EPS foam inside the basement instead of XPS on the exterior. The XPS gets beat up above grade and limits bearing if I need it on the exterior. No exterior foam and I can set my wall flush to the block and still use 2x4's.If I wanted a clear span basement I would use 2x4 floor trusses hung by the top chord like another poster suggested. With floor trusses I can see sheathing the exterior wall on the floor and standing it up, but I still don't know how I would build that exterior wall with TGI's or 2x floor joists without sheathing later which I despise to do.With sheathing on the exterior and 2nd floor bearing on the interior wall, I would use metal diagonal bracing on the interior. I might not even kerf them in, just nail them upside down to the exterior side and stand the wall.
To All: I wrote the JLC article. E-mail me if you want a copy.
Thanks for posting this offer and for E-mailing the file to me.
Very well conceived and written article, giving plenty of details about methods and materials. Very impressive concept and execution. I'll be studying it carefully and borrowing from what I learn on my next project.
I strongly recommend that anyone interested in this topic take Dan up on his offer and E-mail him a request for that file.
Yes, I joined the top plates with a strip of plywood. My wall was 9" thick, so it had a 2" space between the plates. We were dealing with a very conservative electrical inspector, so the electrician chose to drill the studs. Really, how long does it take to drill studs anyway? I don't think the electrician thought it was worth stapling AND explaining himself to the inspector. Another detail that hit me was on basement walkout walls with ICF forms, the 2x4 did not provide sufficient bearing surface, so the outer wall had to by 2x6 in those cases.
Thanks for completing the picture for me.
May I suggest that you take a look at the JLC article that Dancing Dan wrote and has offered to share with us all. Lots of well conceived methods in there.
Here's a link to a recent discussion over at JLC http://forums.jlconline.com/forums/showthread.php?t=48162
Thanks for the link to that JLC discussion. I read the first few posts and am impressed by the contributors' knowledge and experience. I'll read the rest of it over this weekend.
I really can appreciate why you want a double wall. Lack of heat transferance is your goal. Since there are other ways to achieve that goal you need to consider those as well.
I refer to both SIP's and ICF's..
True you don't have any experiance building those but it sounds like you don't have any experiance building a mooney wall either..
It may be a simple matter of your comfort level. You are familar with stick built homes and anything else seems as complex as me learning how to use a computer..
Perhaps that's why I'm such a vocal fan of those two systems rather than the compromise of a double wall system..
I never had much experiance stick building.. I wasn't mentally committed to it..
I can say that my house is extremely comfortable both winter and summer. Thus far this summer I've run my A/C less than 30 hours total. (and I use two small window units so the expense didn't raise my electric bill hardly at all)
Frenchy,
You're making assumptions about how I think which don't match up with the investigations I've made about other building methods and written about at length on this board.
You've been involved in those previous discussions so it's reasonable to expect you to show better judgement than expressing your unfounded assumptions and opinions about how I make decisions.
If I could put my opinion of your ignorant assumptions in vulgar terms here or in person, you can bet that I wouldn't miss the opportunity.
Edited 8/1/2009 12:31 pm by Hudson Valley Carpenter
I tried to be polite and understanding..
I accept that you don't want to do SIP's or ICF's You have mentioned your experiance so I did make the assumption that it was because of familarity.
If you say you have no such experiance then an apology is due..
You have mentioned your experiance
Experience (without rancor): I began earning a living in the building trades in the mid-sixties. I built my first personal use home of my own design in 1967. I learned a lot from building and living in that house, as I have learned from each successive house I've built for myself and lived in.
I've also learned from designing and building homes for clients and from building other custom designs.
One of the best ways I learn is by asking questions of other builders who have worked in the trades for years, doing custom homes and remodels. I'm also open to ideas from first time builders, like yourself.
I've read what you and others have said about ICF's, done several days of research and concluded that the benefits vs cost are far inferior to what can be achieved using other methods.
You, on the other hand, have built one home for yourself. While I admire that accomplishment, I don't believe that it qualifies you to make proclaimations about materials and methods or about the judgement of others who have much greater experience.
I've had this same discussion with you before here on BT, as have other builders. Why don't you move on and try to learn more, rather than playing your one note concerto here every time you feel the urge?
IMO, if you want to sell ICF's and SIP's, you should look for a job with one of the many companies which manufacturer them, rather than forcing your limited opinions on others here.
Cost benefit ratios..
I've pretty well admitted that as things presently stand if pros build as compared to a DIY'er. Pros with the decades of experiance you and many others here have it's no contest.
However, New materials, new techniques, get initial exposure from enthusists and newbies rather than from experianced pros..
As things stand because of their relative rareity Both SIP's and ICF's are more expensive, far more expensive than traditional stick framing is..
That is because of lack of competition and lack of experiance..
If you consider the real costs of foam used in either ICF's or SIP's they sell for many many multiples of their cost of manufacture.. That due to lack of any real efficencies which are the normal byproduct of acceptance and competition.. With a clear clean slate there is absolutely no way Stick framing could be competitive with either.
On the other hand for Do-It-Yourselfers especially with regard to ICF's there is no competition.
Just a few thoughts from a new guy with no agenda.I like a skeleton. Post and beam is nice if I had a wood lot and was building for myself. The market I want to build for is first time buyers of a new house. Simple ranch with full basement. People who want to upgrade from renting or owning an old house. Someone who wants something new. So post and beam is out, and platform framing is in. The SIP bearing wall has no skeleton. It relies on OSB as a structural component. Which works as long as the wet is kept out, either from the inside or the exterior. The frame can take alot of abuse over the years from neglect and still be remodeled to new again. I think SIP will fail in the long run from neglect.ICF's are great. But my local concrete is running $120 yd and climbing. Again for my client price range I'm looking at a 10" block basement w/ EPS and framed walls like the FH article.Right now the cheapest building material up here is 2x4's. Hence the double wall with cellulose. My own house built in the '80's with 2x6 studs and fiberglass batts is not enough when the Clipper winds comes in off of Canada and drop me down to -30º.