aardvarcus
"all the seams are taped, and all penetrations are caulked or foamed". you're right, of course in that the more careful you are with caulking and foam, the more you'll cut down on infltration; especially if you caulk the sheathing to the studs. If you don't you could get air between the 2x & the plywood, coming in below the sheathing. I've seen a lot of framing by good carpenters but the problem is that stopping air by caulking is not (yet) in the radar of most of them, so I lean towards an approach which stops infiltration by more than one method including the use of insulation which blocks it in & of itself.

http://www.coastalforestproducts.com/catalog/files/Envirowall.pdf

Here is an excellent alternative framing approach to eliminate thermal bridging. Staggered stud design is another approach. Securing a sheets of rigid foam board on the exterior of wall sheathing is still another. Foam or cellulose used in conjunction with these methods is tight, efficient and proven.

The recent popularity of SIP's and ICF's leaves me scratching my head. Is this technology proven? We know conventional framing works - we've been building homes like this for decades and they have withstood the test of time. Design freedom, the ability to make on the fly changes to layouts and the ability to make structural alterations without the need of a structural engineer stamp.

I think new home builders and prospective home owners should really think twice about investing money in these fadish construction styles (SIP or ICF) when these two methods of construction have not been in use in residential applications for more than a decade and a half.

Do your homework, check the facts, account for all associated construction costs (ie. crane rental with SIP's), talk to people who built and live in one of these hoems and make an educated decision.

Johnny Boy
"these two methods of construction have not been in use in residential applications for more than a decade and a half."
Actually thats not true - SIPS were used in constructing houses in the late 30's, although I don't know if any of those are still around. I first used stress skin panels over thirty years ago in houses that are still around and still working fine, and I was far from the first to do so. So it is not an unproven technology. One huge advantage with SIPS is their use minimizes infiltration when installed correctly, whereas cutting "normal" infiltration in stick framing takes products and methods that are still unknown to most framing crews.

My other problem with this approach is that it implies that increasing the R value of the walls to by 21%- 27% to R-16 or 17 will somehow help us build the houses of the future, where in reality we need far higher values. It could help as one part of a multi part system, but only if the unit cost is low enough to make that work - which I doubt.

JB, Not proven. What you see in the market today are folks attempting to reach the performance of ICF walls and a SIPs roof. Once you double stud (to avoid stud convection) and go to all the trouble to create a SIP or an ICF on site you are spending money. Thermal mass is real too. Good luck.

this is what you choose for post #1 to this forum?  off to a great start, bud....

Without getting into any of that, I looked at your system.  It seems to me that there would be a lot of waste & a lot of extra labor to cut all of those small strips of osb & foam board, for very little gain.  You could build a conventional wall & cover the entire thing with foam board, which would give you much better performance in a much simpler design.

I'm going to have to disagree here, What's not proven, foamboard? Its a thermal framing break not some digital technology, but I bet it costs alot. You keep posting about icf walls - sips roof, and I do see you are from texas which explains a few things but being from a cold climate my take is: ICF walls are basically air infiltration reduction for dummies, which is great, but then the r-value is lacking unless you have these super thick walls. And how is thermal mass real when you're insulating (buffering) both sides of your "mass". SIP roofs are an ABSOLUTELY horrible idea when osb is involved. Everyone who reroofs homes yearly raise your hand and testify to never seeing osb damage after the tearoff. There's always signs of water issues, sometimes nothing to worry about other times you need to start cutting out sheathing. Easy fix when you can cut it out and replace on a trussed or raftered roof, what do you do when a panels shot on a sip roof? In a cold climate you dont need a conditioned attic and if you need a cathedral go scissor truss. Sip walls give a MUCH better r-value for the thickness and a good crew can focus on the proper installation but their sheathed with osb which is so tempermental to moisture so you add many more critical moisture details to deal with ($$$,) unlike traditional framing where osb could essentially be a sacrificial layer as its easy to repair and replace compared to sips. And seriously, not talking diy weekend warrior here, double stud is not exactly going through much trouble unless your contractor is incompetent; it is after all working with the typical contractors main medium. Its an easy replication a grunt could do after layout. My .02 COLD CLIMATE prediction: Multi construction phase blower door testing will become mandatory per energy codes (and frankly putting auditors to work) as will higher r-values. Given both mandatory requirements and a post-framing pre-drywall blower door test and subsequent envelope adjustment (sealing) the result will be icf's lose, sips have a chance if they prove easier and more durable than stick with foamboard to meet the new rules. Much better chance if they dump osb for the outer skin (I know this is available but everybody needs to start doing it) and much much better chance when economies of scale drops the price of panels. So that's my rant for the day.

It was broken up before I posted it but I see it posted as one giant blob, sorry.

Greentree,

You have some valid points. It seems all of the energy comparisons that we see for stick built is the typical 2x4 or 2x6 walls w/ 1/2" OSB & fiberglass batt insulation with batt insulation in the attic. I guess if I was selling ICF and/or SIP I would be giving the same comparison to make my product more attractive. I would like to see some real energy comparisons if one was to add foam board (comparison w/ 1/2", 1", & 2" to see the difference) to the exterior of the framing sealing/taping the seams, spray foam the bonds, either spray foam the wall cavity & / or spray in dense pack cellulose, proper air sealing, in the attic r49 min. with blown in cellulose (maybe spray foam 1"-2" to air seal, then blown in cellulose on top).

As another comparison, the same as above but staggered stud w/ 2x4's , 2x6 top and bottom plates (comparison if foam board was added to exterior).

Another comparison, the same as above but double stud 2x4 exterior walls (comparison if foam board was added to exterior).

Tree, re: ICF walls: If you don't know about wall capacitance then you might do a little research. The foam on the inside dampens this tradeoff so basically the walls store energy. The heat exchange takes place both ways. Direct attachment of sheetrock with no biodegradable wood behind it is the plus. Once your buiding reaches temperature it will stay there with little effort - like pushing a car that's already moving. I prefer SIPs that do not utlize osb but don't believe i've ever mentioned obs as a desirable material.

Greentree,

 

I get your points.  However, I'm uncertain what you are recommending as the exterior sheeting for the walls and roof if you don't use OSB.  What is your preferred materials in your build?

 

Thanks,

Bruce

 

TexasICF,

I'm from Michigan, and right now it is about 20 degrees or so outside.  I keep my house around 70 degrees or so, which today would leave a differential of 50 degrees.  In my case, if I had ICF, would the concrete temp. between the foam be somewhere in the middle... around 45 degrees or so? I understand that there is ICF blocks that has more foam on the outside than on the inside, so in those cases the concrete would be a little warmer.

Greentree: In his book "Builder's Guide to SIPS", Dr Joe Lstiburek says "in extreme snow climates it is necessary to add a vented air space between the shingles and the SIPS..." Also, Winter Panel in Vermont rercommends venting the roof. THis venting would probably eliminate or greatly minimize any tendency for the OSB to deteriorate, as you are venting the moisture before it hits the moisture barrier of the shingles. Problem is, I don't think most SIPS builders do this because of the extra cost involved. (Installers: is that right?) Amos Winter told me years ago that OSB was more stable than plywood and was used for that reason. Would be nice if they could join it with something like Advantech.

Jere: I did a comparison between SIPS and 2x6/cellulose & 2" XPS; stick was cheaper and same energy rating, providing the infiltration was low enough, which it was. But, I think if SIPS manufacturers lowered their prices to be less than the alternative they would gather market share quickly.

just curious, in doing this comparison are you comparing the stick framed wall to a 6" SIP or 8" SIP?  If you build 2x6 & add the 2" of foam you have an 8" thick wall, so for apples to apples, you should look at the 8" SIP wall right?

I was comparing R value to R value, so it would have had to be the 8" panel. I believe we should be using 8" or thicker panels to get the higher R value at least in the north. I was using the REM Design energy modeling program which is the same one used for the HERS rating, and that program has SIPS as a predetermined wall type. My energy auditor said they've had good results when comparing modeled results with actual energy usage.

That's really good to know.  As I mentioned in previous posts, I'd really like to do SIPs but have to balance cost vs. performance.  It's sounding like our builder will be able to do the blown cellulose + xps cheaper than SIP, so that will free up some money for the window budget.  I'm REALLY trying to make the Serious windows work too.  Oh yeah, and geothermal....  budgets suck.

TexasICF, we have had this discussion before and decided (mostly) that ICF is a lightweight when it comes to thermal mass. Search for "thermal mass." Or go straight to the source at Oak Ridge National Laboratories: http://www.ornl.gov/sci/roofs+walls/research/detailed_papers/thermal/index.html
The building envelope researchers at ORNL say that ICF's thermal mass is worth between 6 percent and 8 percent energy savings over regular stick built with comparable insulation. It comes in third in a list of the four ways to arrange insulation and concrete in a wall. Exterior foam is best. A concrete-insulation-concrete sandwich is second best and interior foam is worst. In the lefthand column, click on "Potential energy savings..."
The Cliff Notes: Mass offers no energy savings whatsoever when the ambient temperature climbs above 80 or falls below 60 and stays there. Heat is only going in one direction, and it's the wrong way. In a power outage, a massive house would stay warmer longer than a low-mass house, but when the lights come back on, it will take that much longer to heat up.
Mass does cuts energy bills when the average daily temperature is something you'd consider comfortable. Even when the thermometer outside swings from 50 to 90 during a 24-hour period, buffering by thermal mass can keep things comfortable inside without need of HVAC. Not surprisingly, it works best when the concrete is directly exposed to the interior. If you look at Figure 8 in the ORNL page mentioned above, "Potential energy savings..." you'll see that reducing the insulation in an ICF wall in Phoenix from R25 to R5 makes it perform BETTER by about 33 percent, and that in Bakersfield, insulation has very little impact on savings. This tradeoff is entirely a function of where you live.
(Divide the year into too hot, too cold and the days in between; the bigger the daily swing, the bigger the savings; drier is better because mass can't do anything about humidity.)

This thread certainly offers a lot of different opinions for would be home builders to sift through in order to determine what best meets their requirements in connection with any new building project that they may be contemplating.
I suppose that it has morphed into a "hijacking" of sorts, with all of the various opinions, suggestions, advice, and "discussions" among the participants. However, that's OK isn't it? Isn't the information that's posted on these forums as much for the 100's of daily "visitors" to the GBT site, as for the instigator of the individual threads?

Having said that, now I get to add some additional thoughts, from my perspective, in response to others who have commented since my earlier posts on this thread.

SIPs (Structural Insulated Panels) have been around, in one form or another for over 50 years. They are an extremely viable option when one is looking to build a super energy efficient structure at a price point that is competitive with the complicated "stick" framing systems that are often discussed in these forums. I've expressed before an OPINION that the only way that the cost of one of these systems is going to be appreciably less than SIPs is if labor is FREE or very CHEAP, and time is not an issue. Having said that, I've worked with many owner builders who have installed their own SIPs, maybe with the assistance of family and friends, with little, or no, investment in labor. Another point here is the simplicity of the system. It is my contention that (and there's much anecdotal evidence to back this up) the "SIP learning curve" is extremely short, particularly for experienced, competent, contractors and framers.
I've virtually seen "the light bulb come on" for contractors who are witnessing a SIP installation for the first time, or even attending a demonstration at a home show or a workshop. Now, I will admit that many individuals who are interested in building with SIPs are discouraged by contractors who are legitimately concerned because they don't understand the system, or, in many cases, don't want to give up the additional revenues that they can generate from
"stick" framing, particularly from one of the "alternative to SIPs" methods. I've commented to a number of contractors over the years that "If you want to get aboard with a "new" technology, you shouldn't expect your client to pay your tuition" (some buy into this theory, some don't)

Following are some additional points in support of SIPs:

Is it really "greener" to use 2 to 3 times as much lumber? (As with the DSW (Double Stud Wall) system) Some of the suggestions that have been proposed in these forums would result in walls from 8" to 16" thick (still more lumber)

The "SSW" (Staggered Stud Wall)? Wouldn't you at least need a stud at every 12", and that gives you 24" spacing on each side for attaching siding and drywall, which I know is acceptable, but not necessarily as satisfactory as 16" OC spacing (Neither of which is as efficient as having the OSB sheathing on the interior side of the exterior wall, for easier, faster, and less wasteful, drywall installation. Also, many finish carpenters have commented on how nice it is to work with a wall that is perfectly flat and plumb)

SIP jobsites typically generate less waste for the landfills (That is when pre-cut, ready to assemble, panels are delivered to the jobsite) Actually, in the case of projects that have been designed to best utilize the 4' or 8' SIP module, not much fabrication is required required anyway so standard production sized panels can be used. The scraps that are generated from this approach are generally large enough to be used for something else or on another project. None of this is intended to imply that we can't effectively utilize SIPs in connection with more complex, custom, designs, we do it all the time. It's just that when the "B" word (budget) is a primary concern, what are the priorities?
Performance, function, comfort, `etc? or Style, size, and "bling"? (Uh oh,sorry, I'm afraid that I'm having a "Yogi moment" as in "this is like deja vu all over again", in other words I'm sure that I expressed a similar sentiment in an earlier post on this thread)

There is considerable evidence that SIP structures are stronger than those that are conventionally framed. For example see articles about the survival of SIP homes that were located near the epicenter of the Kobe earthquake as well as a house that remained virtually intact while being blown off of its foundation by a tornado in Tennessee, at www.r-control.com (Does anyone think that homes constructed with a "DSW or "SSW" system would have fared as well?)

In regards to all of the negative comments about OSB. It is still the most widely used product in the US, both for SIP "skins" and conventional sheathing applications. It's a "sustainable" building material (can go into details if necessary) It is dimensionally uniform, with no voids. OSB SIPs are available in sizes up to 8' x 24' which, where appropriate, allows for a large floor, wall, or roof, area to be covered by a single panel. (YES, a crane, pettibone, forkilift, or some type of mechanical lifting device, is usually required to install these "jumbo" panels, particularly in the case of roof applications) Also, it should go without saying, as with any building product, proper design and installation, is imperative, if one expects optimum performance. And, local codes, weather, and building site conditions, are critical in the planning and design phases of any building project. As has been pointed out many times on these forums, this is where, in many cases, an "expert" may be "cheap at twice the price".

ICF's? I don't think that anyone would argue that they're not stronger than SIPs, or than any of the stick framed systems that are being discussed. However, In my area, California, a finished ICF wall is considerably more expensive than a SIP wall so benefits and budget considerations are key if one has narrowed their choices down to one of these two systems. I won't even get into the B&B (Benefits and Budget) issues of SIPS vs Concrete for roofs because I have no experience with the latter (But I'm willing to get up to speed with this option when the opportunity presents itself)

My perception regarding the actual comparison of the energy efficiency of SIP walls vs ICF walls is that, in most areas, a 6 1/2" SIP (5 1/2") of EPS is comparable to an ICF wall with 6" to 8" of concrete and 2 1/2" of EPS on each side. Now, I'm still in an educational mode in connection with the real world "thermal mass" benefits of an ICF wall. I understand the concept but I'm still a bit perplexed by the diversity of claims and explanations that are tossed around out there. Maybe Dana1 will now jump in and clarify this issue for us.

By the way, Jere, TF, the original "Vertical" ICF system does offer the option of as little as 2" of foam on the interior side, with up to 12" on the exterior (though 4" to 6" is likely to be sufficient in most areas)

In the meantime, as I've been composing this post, I see that it appears that jerkylip's contractor has convinced him that he can provide him with a stick framed wall that will perform as well as SIPs at a "cheaper" price (I'm assuming that this will be a "substantially cheaper" price since there is going to be enough extra $$ to go for upgraded windows.........and geothermal?) Hey, Jerkylips, we all understand "budget", good luck, and let us know how things turn out once you're underway, and your home is completed. By the way, ask your contractor if he's priced in KD lumber, and ask about the moisture content of the blown in cellulose, and be sure that he doesn't "rock" until its completely dry. (This latter statement is not intended to imply that wet blown cellulose is not a safe, viable, and effective, insulation option. However, as I previously stated, just as is the case with any building product, proper design and installation is imperative.)

Next?

Hello Sipper. Great post! Thanks, Steve

OK, I'll bite:
"I've expressed before an OPINION that the only way that the cost of one of these systems is going to be appreciably less than SIPs is if labor is FREE or very CHEAP"

Let me give you some FACTS: Last house I quoted stick with XPS vs precut SIPS. R value = R value. Infiltration rate = infiltration rate. Got written quotes from framing company (not estimates) for labor and material. They do their own panelizing of stick walls; not the cheapest framer around by any means & they do excellent work. Also got written quotes from two (2) SIPS companies - one who installs their own. Results: SIPS more expensive. Stick + cellulose + XPS, plus rainscreen, all installed= 94,991.38. SIPS, fabricated off site + rainscreen, all installed= 116,577.34. I like SIPS, have long history going back 32 years with them; I'd like to use them. Problem is, in a competitive environment selling the same result for more $$ doesn't get many takers. BTW Dense packed cellulose is dry & doesn't need to dry in the wall like wet spray cellulose.