Anyone built with SIPs?

[cbcansurvive]

Structural Insulated Panels (SIPs), for those who have never heard of them are panels which consist of a "sandwich" of an oriented strand board outer skin, a rigid foam core, and another oriented strand board outer skin. Picture a sheet of of foam insulation with sheets of OSB glued to either side. You can see what they look like here and watch a video about how they work here. Basically SIP homes come in panelized kits that are put together like puzzle pieces. The SIPs form the shell of the building (outer walls and roof)-conventional stick framing is used to form interior walls and floors. The SIPs used to make up the roof only need a "post and beam" style structure to hold them up since they are very rigid and strong. I am seriously considering building with these for a number of reasons.

First, the energy savings are pretty impressive. A 6.5" (you can get them thicker) is rated around R-30 depending on the type of foam used, and that's just for the panel-whatever is applied to the outside plus the sheetrock on the inside provides a bit more insulation. The average 2x6 stick framed wall is about R-15. Those are just calculated numbers though. Stick framed walls have what are called "cold bridges"-the studs which bridge the gap between the outer sheathing and the sheetrock on the inside. A lot of heat is lost through these-SIPs do not have them, so in the real world application the insulation factor is even greater compared to stick built. Next, if you watch a little of the video you can see how easily they go together. This is important because we plan to build our own home and constructing the entire dried in shell quickly would be a huge help. I know I sound pretty convinced at this point, but I'm a skeptic at heart, so I'm trying to get some feedback from folks who have actually built a home with these things and any pitfalls, setbacks, or other difficulties. I'm also eager to hear about actual energy savings, and addressing air movement issues since these homes are so tightly constructed.

In case you're curious, we plan on building something similar to this, which may seem odd since its a log home, but the log companies are now making pretty convincing false corners to compliment their log siding, so you really can have an authentic looking log home now without the drafts, leaks, etc...(I know because I grew up in one) I'm also hoping that the energy savings are as good as they claim-we're planning on supplying all heat and domestic hot water through a wood gasification boiler and home built flat plate solar collectors. The energy savings combined with the efficiency of the gasifier and the free heat from the sun should allow us to conserve our woodlot for years to come. So, any homesteaders building with SIPs out there?

[ErinP]

We seriously considered it. You're right. They make a very convincing case!
But the DIY factor wasn't really there. I mean, yeah, you can put them up yourself, but it's considerably more difficult.
I also don't like how much "fake" material is used. The more time goes by, the more I come to realize that the materials that make up my human environment should be as healthy as absolutely possible. I want "natural" wherever I possibly can.
(Or really old so that all the off-gassing has already given someone else cancer. )

However, I'm REALLY sold on the sealed-envelope type of insulating system that SIPs give, so this is what I found as a compromise:
FirstDay Cottages
It's a modified post and beam frame. No composite materials except in the insulation itself. Construction is straight-forward and very DIY-friendly and, best of all, it uses that sealed-envelope system of solid insulation with no thermal bridging (except at obvious holes like doors/windows!)
Step 1. Erect the frame
Step 2. Sheathe the outside of the frame with the 1xT&G that'll make the interior wall surface.
Step 3. Sheathe the outside with poly-iso insulation boards
Step 4. Sheathe one last time with the 1x that makes the exterior siding.

[tiogacounty]

I've done a few SIPS houses as a volunteer in some really cold areas of SD. and MT. They perform real well, and they certainly avoid a lot of thermal bridging. They can be used to create a really energy efficient house. Issues include the fact that they are not the least bit DIY friendly. They are heavy, bulky, very difficult to deal with once you are above the first story walls, tough to wire, and need to be installed with great attention to detail for the system to perform properly. They also can create a very air-tight structure that needs an air exchanger or heat recover ventilator. As for the foam and boards approach of the other suggestion....This could get real ugly fast. Foam on the outside of structures can create a real disaster. Everything from water saturation, wrong side vapor barriers, insect infestation etc.... IMHE, Insulation belongs in walls, not nailed to the outside. The exterior should be sheathed in a ridged material, like plywood or OSB and covered with a high grade house wrap, Tyvek or similar. Then all the windows, doors and other penetrations need to be properly flashed and sealed. It now required and industry standard to do it that way. Building up layers of Iso board and covering them with pine boards is looking for trouble. I have done extensive repairs on structures less than ten years old, with foam sheathing and a lack of a proper "drainage plane" to direct water out of the wall, when it inevitably penetrates at doors and windows. It gets rotten, moldy and insect infested remarkably fast, and it is extremely expensive to repair.

[ErinP]

I just listed basic structure...
I figured anyone who was interested would click on the link I posted and see that house wrap is applied (between the sheathing and the insulation) as well as flashing, etc.

So far as "getting ugly really fast" I guess that's possible. That method has only been in use (that I'm aware of) for 30 years or so. It's entirely possible that it will be failing any day now...

Insulation belongs in walls, not nailed to the outside.

By this I assume that you don't believe in putting a layer of foam under new siding??
That's really unusual...

[Common Tator]

I'll be watching this thread to see what others have experienced. I would love to use SIPS, if they work as advertised.

[cbcansurvive]

Originally Posted by tiogacounty

I've done a few SIPS houses as a volunteer in some really cold areas of SD. and MT. They perform real well, and they certainly avoid a lot of thermal bridging. They can be used to create a really energy efficient house. Issues include the fact that they are not the least bit DIY friendly. They are heavy, bulky, very difficult to deal with once you are above the first story walls, tough to wire, and need to be installed with great attention to detail for the system to perform properly.

All good points to consider. As far as getting the second floor/roof panels up I would think that the best way to go would be to rent a large man-lift. By hand it could be done but you'd need a lot of people. The wiring is certainly more of a challenge than stick framing, but not insurmountable I would think. Great attention to detail is always important though isn't it?

Originally Posted by tiogacounty

They also can create a very air-tight structure that needs an air exchanger or heat recover ventilator.

Very good point-this is totally uncharted territory for me. Obviously the air-tightness helps a great deal with the energy efficiency, but this also requires mechanical ventilation to keep the air fresh and clean. I'm assuming that a heat recovery ventilator ensures that you're not pumping your nice warm air outside. We plan on installing hot water heat-not sure if this makes a difference at all. Guess I better do a little research.

[tiogacounty]

Originally Posted by ErinP

I just listed basic structure...
I figured anyone who was interested would click on the link I posted and see that house wrap is applied (between the sheathing and the insulation) as well as flashing, etc.

So far as "getting ugly really fast" I guess that's possible. That method has only been in use (that I'm aware of) for 30 years or so. It's entirely possible that it will be failing any day now...


By this I assume that you don't believe in putting a layer of foam under new siding??
That's really unusual...

I actually had a complete structural failure of a new home within seven years of occupancy, and I am hardly alone on this issue. The house had typical construction with the exception of a layer of 1/2" extruded polystyrene added under the siding. The windows had an issue that allowed water to penetrate the sill in extreme conditions, as in high winds and heavy rain. The water was trapped by the foam on one side and the full poly vapor barrier on the interior. The front wall of the house was collapsing with rotten band joists, plates and headers. In that case the attached garage was fine, the windows leaked in the same manner and left slightly discoloration on the rough sills and plywood sheathing. The garage and house were built the same, the only difference was the lack of foam sheathing. The garage, therefore, had the potential to full dry between these unusual weather events, preventing damage. I have also done major structural repairs to other fairly new homes that were similarly constructed, including replacing an entire corner of a home that had an miniscule flashing leak, yet the foam had so effectively sealed all the moisture in and rotted a significant portion of two walls and part of the floor system.In a similar situation, EIFS (or Dryvit) exterior foam installations on thousands of homes homes created astounding amounts of damage for many of the same reasons, including the inability to properly dry out the wall and reach a mold free moisture equalibrium between saturation events. Damage caused by foam sheathing, wrong side vapor barriers, failures in, or lack of, an effective drainage plane, and other issues created by an attempt to increase insulation levels are far from new, or unheard of.
As for your claim that housewrap is being used properly, and for the last thirty years in the method shown? Doubtful, yes it may be used as pictured, but it is an invitation to failure. At no point will you find a reputable house wrap manufacturer recommending that it's product be used to in the middle of an exterior wall assembly. Also, by continuing the layering on top of the housewrap with strapping, more Iso board, windows, doors and other penetrations, the ability to effectively seal the exterior as an air tight, water tight drainage plane is basically non-existent.
So to answer your questions. No I no longer put foam sheathing of any type under siding. I would never recommend it, or buy an existing structure with this system in place. Failures are well known in the industry and hardly unusual. Second, the method show of a lightly construction post and beam, multiple layer of foam, and boards clearly had a huge potential for issues. Just because a building looks attractive and isn't falling down doesn't mean that it's well engineered, executed, or durable. Until you have pulled siding, and foam, off of a building, then removed framing that was the consistency of potting soil, it's hard to appreciate how easy it is to build a building that can destroy itself in a few years. There are a lot of complicated, interdependent issues at work when designing, building and living in an energy efficient building. At any step along the way, a great idea can turn to mush. SIPS can be great, or a disaster. They are now discovering the obvious regarding SIPS used in extreme climates. If you have any void from a lack of proper detailing, such as an improperly spray foamed joint or other missed framing void, the air passing through the void will condense and quickly start to get moldy and rot. There are reports of SIPS homes in Alaska with major issues due to minor detailing mistakes during the construction process. The same mistakes made in Va, or NV might never be an issue. The whole situation is extremely complex, climate dependent and often leads to hidden issues that are only discovered after the mold and the insects take up residence. A building that performs well for thirty years in one environment may be in serious trouble during it's first winter in another locale.

[painterswife]

Living in a SIP home about 8 years now. Will build this way again.

I just love watching the snow and wind going sideways in the winter and not feeling a bit of draft.

We had the shell put up and then did all the rest ourselves. We could have done the shell but did not have the time. We will do it ourselves next time.

[Common Tator]

Has anyone tried the sprayed foam insulation with stud and frame construction? Does that also have problems with retained moisture? I keep seeing it used on the home improvement shows, and I keep hearng that a vapor barrier isn't necessary.

[ErinP]

Originally Posted by tiogacounty

The windows had an issue that allowed water to penetrate the sill in extreme conditions, as in high winds and heavy rain. The water was trapped by the foam on one side and the full poly vapor barrier on the interior.

So correct me if I'm reading this wrong--This was all caused by the windows being improperly flashed/sealed, yes?
If the foam is the problem, why is it still recommended?

As for your claim that housewrap is being used properly, and for the last thirty years in the method shown? Doubtful, yes it may be used as pictured, but it is an invitation to failure. At no point will you find a reputable house wrap manufacturer recommending that it's product be used to in the middle of an exterior wall assembly.

Middle of the exterior wall?
Again, I think it's fairly obvious you haven't actually investigated the link I posted...

Second, the method show of a lightly construction post and beam, multiple layer of foam, and boards clearly had a huge potential for issues.

Multiple layers??
Now I'm positive you really don't understand what you're talking about...


But then, you earlier said:

The exterior should be sheathed in a ridged material, like plywood or OSB

in relation to a post and beam structure.
Which of course is redundant. Otherwise how would timber-framed structures have stayed up for centuries without a "ridged material" like ply or OSB?


I realize you have experience to share. But it would seem that experience is primarily in standard, stud-framed structures and you're having trouble getting out of that box...

[Riverdale]

Back in the early 90's I worked on one in the little bit of Charlevoix County on the west side of Six Mile Lake. The worst part about it was the wiring. It was a major pain.

The best part, you could put a window wherever you wanted one.

The walls (and roof) went up fast.

It was one of the first housed I worked on with the engineered plywood floor joists. Interesting seeing a 28' wide clear span basement.

[MushCreek]

SIP's are not all that hard to put up as long as you have the man power and/or equipment. They can go up much faster than framing and conventional insulation. The best I've seen are metal SIP's. They are fully weatherproof, and are used as-is on commercial buildings, with no further siding. Of course, that would be ugly on a house! The easiest way to deal with wiring and plumbing is to put shallow metal studs up, wire everything, and put drywall on top of that. It does make for thicker walls, though.

As for foam sheathing- it works great, and eliminates thermal bridging, IF it is done right. I've put a lot of research into this in the last 4 years, and a lot of changes and advances have been made. The best method is to sheath the house like usual. Then put house wrap on it. The foam layer(s) is then installed, and the seams are taped. Two layers of 1" foam, with the seams staggered and taped is both air and water tight. You then have to create a drainage plane, which is recommended anyhow. Vertical strips of furring are screwed on over the foam. The siding is applied to the furring. This creates a drainage plane so that water driven under the siding has somewhere to go, rather than sit there and cause trouble. Clapboards should also have a flashing piece put under butted seams to prevent water from entering there. The bottom of the foam needs to have a protective barrier to keep critters out, and the drainage plane has a special barrier at the top and bottom to allow ventilation, but keep the aforementioned critters out. Regardless of how the house is built, window flashing is very important, and rarely done properly. Sound like a lot of work? It is, to do it right. But anything less will simply result in failure of one kind or another.

If I had the money, I'd either build my house form ICF or metal SIP's. It's likely I won't be able to afford either, so it will probably be the system I described above, although it's a lot more labor than ICF or SIP's. Labor is the one thing I DO have!

The other problem with any of these systems is the you HAVE to have a ventilation system, such as an HRV, to exchange fresh air with the outside. I think we're going to see a lot more people with sick-building syndrome now that hermetically sealed houses are becoming code. BTW- Metal SIP's can't out gas, since the metal skin is impervious and inert.

[Witterbound]

We look into using SIPs, and decided the cost and DIYability wasn't in us, so we went with stick framing (on the outside of our post and beam home), with sprayed in foam insulation in the walls, and 2 3" layers of 4x8 foam panels on the roof. In addition, with SIPs you need to have everything planned in advance (doors, windows & electrical), so that it can all be made up that way at the factory. We liked the ability to change these things as our house went up. We used ICFs for 1/2 our basement. The other 1/2 is stick construction with sprayed in foam.

[ErinP]

Originally Posted by MushCreek

As for foam sheathing- it works great, and eliminates thermal bridging, IF it is done right. I've put a lot of research into this in the last 4 years, and a lot of changes and advances have been made. The best method is to sheath the house like usual. Then put house wrap on it. The foam layer(s) is then installed, and the seams are taped. Two layers of 1" foam, with the seams staggered and taped is both air and water tight. You then have to create a drainage plane, which is recommended anyhow. Vertical strips of furring are screwed on over the foam. The siding is applied to the furring. This creates a drainage plane so that water driven under the siding has somewhere to go, rather than sit there and cause trouble. Clapboards should also have a flashing piece put under butted seams to prevent water from entering there. The bottom of the foam needs to have a protective barrier to keep critters out, and the drainage plane has a special barrier at the top and bottom to allow ventilation, but keep the aforementioned critters out. Regardless of how the house is built, window flashing is very important, and rarely done properly. Sound like a lot of work? It is, to do it right. But anything less will simply result in failure of one kind or another.

Exactly.
Here's a really good write-up on the science and function of housewraps/vapor barriers/retarders, btw, for anyone who's interested.
http://bct.eco.umass.edu/publication...tion-barriers/

And here's one that actually tested individual types and brands.
http://bct.eco.umass.edu/publication...ky-housewraps/

[sammyd]

with SIPs you need to have everything planned in advance (doors, windows & electrical), so that it can all be made up that way at the factory.

valu build includes the tools to put your own holes in the walls as part of their kit. They also include a chaseway in the panels for wiring.

[tiogacounty]

Erin, You might want to dial back a bit on the arrogance and tell us of your real world experience, as in, swinging from the scaffold repair rot infested newer homes, installing SIPS panels with a crane, building low cost super-insulated homes in brutal climates and ending up with $1/day utility bills, erecting timber frames you cut yourself or what?..... Not to sound arrogant, but after a few decades I've done these things and learned a little bit. I have spent a huge amount of time and money fixing failures, some of which I created by following "great ideas" from folks that had a product to sell, and no real concern if it was good, or stood the test of time.
To address your comments
#1 The windows on this home were defective and allowed water to penetrate into the wall cavity. In the part of the building with no external foam vapor barrier (the garage) the wall cavity had the ability to dry below 50% R.H between extreme weather events and there was no damage. In the area of the structure with a wrong side vapor barrier (extruded polystrene, specifically DOW brand "blueboard), there was no potential for drying and severe rot ensued. This is becoming more of an issue as more homes are done in this manner, and more older homes are resided with the addition of a foam vapor barrier on the exterior of the structure. Defective windows are far from an isolated issue. I just spent time speaking with a homeowner from coastal VA who replaced the entire front wall of his two story colonial. The issue? Wind driven rain, vinyl windows that failed and allowed moisture to penetrate the wall cavity, 1/2" Poly-Iso sheathing and a brick facing. The brick hid the damage until the drywall turned black, the wall was full of black mold, and the framing was mush. $20K later, the front wall is back up. Fourteen year old house BTW. But, don't listen to what I say, I'm clueless.
#2 Regarding the "Layering of foam issue", I made an incorrect assumption based on a real basic assumption. The house pictures shown on the website show a structure wrapped in housewrap and being sheathed. Give the fact that it appears to be a single 1-1/2 to 2" layer of foam, I assumed that the housewrap is covering another layer of the same product. A reasonable assumption based on the fact that you are not even getting close to an acceptable level of insulation with a single thin layer of ISO-board. Current code requirements require a MINIMUM of R21 in heating climates. The OP's question refers to SIPS, and energy efficiency. You don't build a SIPS structure with the goal of meeting minimum energy standards. Typically SIPS, in a heating climate are 6-8" thick. IMHO, this home pictured is not only poorly built, but GROSSLY under-insulated. This is all meaningless, except for two issues. It would be exceptionally difficult to get the pictured home passed most code officials that I deal with, for a lot of issues including structural, fire and energy code deficiencies. The other big issue still remains and that is the fact that the housewrap is still a wrong side vapor barrier, and in the wrong location. As I have stated previously, this is using a product in a manner inconsistent with what is know in the industry as "AMI" or according to manufacturer's instructions. Any decent building code official would flag this technique and need to see an engineer accept responsibility for a move like that, and for good reason.
3. Your question about timber framing and durability is complex and often misunderstood by folks that are not builders and structural engineers. First of all the link you posted is not of a timber framed structure, it is post and beam, which is a huge difference. Second timber framed structures are only as durable as the maintenance they get. I have seen barns that look great at 300 years old. I have seen many barns in my area, (an area rich with not only timber barns, but covered bridges) that fail is 10-15 years after the roof first starts to leak. As for the need for structural sheathing? A well designed and built timber frame is properly braced with diagonal bracing (knee braces) and will stand fairly straight and rigid without the use of sheathing. However, a timber-framed structure, without any exterior wall coverings, is unbelievably flexible and "bendable", way less rigid than a well build stick framed structure! I have erected and repaired several timber frames. It is common to use cables and ratchets to make huge adjustments to the structure prior to spiking the SIPS panels on. That said, barns are typically sheathed in board siding and have at least roof strapping installed to provide a measure of shear bracing against wind and other dynamic loading. In this discussion, structural sheathing on a modern building, IE, stick built, SIPS, panelized, etc, provide a smooth, solid nailbase for exterior wall finishes and, if installed correctly, contributes enormous amounts of structural strength to the structure. It provides bracing against dynamic loads such as wind, snow and seismic loads, and it provides a huge amount of structural rigidity for static loads. It also makes a great base for a properly detailed drainage plain, one of the keys to a durable structure.
In closing, Mushcreek provides some excellent info. in his post. Specifically he is referring to a system know as a "vented rain screen" It is expensive and difficult to detail properly, but it will result in a very durable structure that dries out properly. I have seen a few failures in some of the techniques he describes however. First, as I have rambled on at length about. The housewrap need to be the last layer, not behind a few layers of foam. Second, foam and various tapes, in particular those listed as housewrap tapes, do not make for a durable drainage plane. I have seen this method fail in installations that were only a few years old. Foam, particularly on the south side of homes, can shrink, causing fractures in the tape, or allowing the tape to delaminate from one side of the joint. The tape itself can loose it's plasticizers and get brittle, even if it's protected from UV damage. And don't forget, carpenter ants, termites, mice and earwigs are all quite fond of foam, apparently it's warm and delicious. Hope this info, help somebody out there? It's one thing to be an "armchair expert" or fall for a builder, or manufacturer that has a great way to re-invent the wheel. It's quite another to spent the last few decades in the field and see what works and what fails. Good luck

[SolarGary]

Originally Posted by cbcansurvive

Structural Insulated Panels (SIPs), for those who have never heard of them are panels which consist of a "sandwich" of an oriented strand board outer skin, a rigid foam core, and another oriented strand board outer skin. Picture a sheet of of foam insulation with sheets of OSB glued to either side. You can see what they look like here and watch a video about how they work here. Basically SIP homes come in panelized kits that are put together like puzzle pieces. The SIPs form the shell of the building (outer walls and roof)-conventional stick framing is used to form interior walls and floors. The SIPs used to make up the roof only need a "post and beam" style structure to hold them up since they are very rigid and strong. I am seriously considering building with these for a number of reasons.

First, the energy savings are pretty impressive. A 6.5" (you can get them thicker) is rated around R-30 depending on the type of foam used, and that's just for the panel-whatever is applied to the outside plus the sheetrock on the inside provides a bit more insulation. The average 2x6 stick framed wall is about R-15. Those are just calculated numbers though. Stick framed walls have what are called "cold bridges"-the studs which bridge the gap between the outer sheathing and the sheetrock on the inside. A lot of heat is lost through these-SIPs do not have them, so in the real world application the insulation factor is even greater compared to stick built. Next, if you watch a little of the video you can see how easily they go together. This is important because we plan to build our own home and constructing the entire dried in shell quickly would be a huge help. I know I sound pretty convinced at this point, but I'm a skeptic at heart, so I'm trying to get some feedback from folks who have actually built a home with these things and any pitfalls, setbacks, or other difficulties. I'm also eager to hear about actual energy savings, and addressing air movement issues since these homes are so tightly constructed.

In case you're curious, we plan on building something similar to this, which may seem odd since its a log home, but the log companies are now making pretty convincing false corners to compliment their log siding, so you really can have an authentic looking log home now without the drafts, leaks, etc...(I know because I grew up in one) I'm also hoping that the energy savings are as good as they claim-we're planning on supplying all heat and domestic hot water through a wood gasification boiler and home built flat plate solar collectors. The energy savings combined with the efficiency of the gasifier and the free heat from the sun should allow us to conserve our woodlot for years to come. So, any homesteaders building with SIPs out there?

Hi,
I think the SIPS can be quite a good choice, but, as others have pointed out, they are susceptible to any kinds of defects that allow water penetration.

Not to argue against the SIP approach, but another couple methods you might consider, which will also give a good wall with low thermal bridging, and might be cheaper and more DIY friendly:

The double stud wall:
http://www.builditsolar.com/Projects...nps.htm#Double
and,
http://www.builditsolar.com/Projects...ZeroEnergy.htm

The horizontally strapped wall:
http://www.builditsolar.com/Projects...onps.htm#Stick
(see the "Gimmie Shelter, "Mooney Wall" links)


More alternatives:
http://www.builditsolar.com/Projects...tructionps.htm

Gary

[ErinP]

My apologies, tioga. How DARE I think there are other options.


BTW, it's obvious you STILL haven't read up on the method I posted. And no, looking at the pictures doesn't count. lol

[texican]

No go for me.

I've never seen any SIP's available for salvage. Actually never seen or heard of anyone using them in this area.

Not salvageable, not scroungable, you can't grow em, you can't make em... you have to buy them, and have a crane on site to place them. Absolutely great, if you're having someone build your home for you... as long as you don't have any problems with flakeboard. Several years ago, I made my living re-finishing homes... made quite a few 'boat payments' off of flakeboard... get it it a little wet and it goes south immediately. I've 'heard' that it's better now... I'm yet to be convinced.

[PhilJohnson]

If I were to build a house I would build a cordwood house. It is very DYI friendly and cheap