SIPs (Structural Insulated Panel) on a Grass Roots Level?: Off-topic discussion forum: Grassroots Motorsports Magazine

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Jan. 29, 2011 2:02 a.m. Hasbro HalfDork

Could it be feasable to build SIPs on a personal, not commercial, level? Or would the technology/cost of set up be too much? I've looked at a bunch of web pages but wanted to see what yous guys think. This is, after all, the place of ALL KNOWLEDGE.

I've been designing houses as a hobby since I was a kid, have built a fair amount of additions etc. and have a pretty broad understanding of house building including pole, passive solar, bale, cantilever, yada, yada, and was a home/commercial/ building inspector until moving to Tucson to care for a terminally ill brother. But I still design a lot and SIPs could be integrated into just about anything (including a modern Celtic home structure I'm currently messing with, lol). The closest to SIPs I ever did was building two garage doors (4 halves) with solid polyisosyanurate cores. R30+. They were incredibly solid and quiet. It took 160 hours but was the most gratifying building project of all projects and really hooked me.

Could a guy like me do it on a small scale for cheap. One small house?
Jan. 29, 2011 2:13 a.m. Hasbro HalfDork

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Jan. 29, 2011 2:15 a.m. Hasbro HalfDork

I have also wondered the same about interior and exterior spray on insulation.
Jan. 29, 2011 8:47 a.m. Curmudgeon SuperDork

There was a 'Dirty Jobs' episode where Mike Rowe was helping with a spray in insulation. While not true SIP, I thought it was cool because it was sprayed in after the framing was completed and filled all the nooks and crannies around electrical boxes etc. After it set, they used something very similar to an old fashioned reel lawnmower to remove the excess. Then you put up a plastic vapor barrier and installed the inside finish (drywall or etc).

EDIT: It was spray cellulose insulation, like this: http://www.advancedinsulationinc.com/newconstruction/cellulose/default.htm
Jan. 29, 2011 9:30 a.m. carguy123 SuperDork

You can buy spray on foam and DIY. I've done a couple of metal buildings. It's not cheap and it's messy, but you finally get the hang of it.

I saw some SIP panels being assembled and they used a different foam than is usually used in home construction. It looked and felt like regular styrofoam. They just had huge, thick sheets and bonded wood on either side.
Jan. 29, 2011 12:08 p.m. digdug18 HalfDork

You can use the solid sheets of foam, 2" or 3" thick on the exterior of your house, roof, etc. It is expensive and time consuming though, not to mention that you need to then build out your windows and doors. You can make your house much more energy efficient doing so though, but at what cost. Google energy retrofit to find more information.

Andrew
Jan. 29, 2011 11:03 p.m. Hasbro HalfDork

I'm talking about actually creating the foam process in a non factory situation. Can it be dumbed down to a garage procedure?
Jan. 30, 2011 2:46 p.m. digdug18 HalfDork

I'd guess you could make your own, from 4" of foam and OSB, thats all it really is. I believe they use lots of glue to bind them together. The benefit you have of actually using SIP's is that the ends overlap each other, creating a tight bond with the next panel.

What are you trying to make with them though? There are more cost and time effective ways of insulating then either making or using SIP's.

Andrew
Jan. 30, 2011 3:43 p.m. patgizz SuperDork

the panels we used to use were 6 1/2" thick. the middle was 5 1/2" of white styrofoam laminated with 1/2" osb on each side. the panels were 4 feet wide, and made with 1 1/2" extra OSB all around so they could be fastened together with a doubled up 2x6. we only used them for floors for patio enclosures, and most had aluminum laminated to the bottom side to make them water tight. a 2x6 ledger was bolted to the wall and they were slid right over it and at the outside they sat on a beam just like a traditional deck would be framed.
Jan. 30, 2011 7:07 p.m. S2 New Reader

SIPS are also a structural member- a stressed skin panel. I suppose you could do it yourself, but make sure you use the right glue(s). I'd be leery of trying to make a structural panel myself unless I was VERY familiar with the manufacture of standard SIPS panels, because they are what is holding the house up. Doesn't mean you can or can't do it, just be aware. I think SIPS are cool (and pretty strong), but you can also apply rigid insulation to the exterior of conventional construction to add insulation, prevent thermal bridges, and add lateral strength when fully glued. It is often cheaper to go that route than purchasing SIPS, but if you can figure out how to roll your own, your results may differ. Good luck whatever way you go- let us know what you decide and if you figure out the SIPS hack- post a build page
Jan. 30, 2011 11:59 p.m. Hasbro HalfDork

In reply to S2:

Thanks. It wouldn't be cost effective to use pre made rigid foam. The doors I mentioned were very costly. My main inquiry would be re. making the insulation itself. I'll keep looking, there must be someone mixing this stuff up.
Jan. 31, 2011 11:56 a.m. Ian F SuperDork

I remember some 25 years ago when This Old House did the famous barn-reconstruction project where the used foam panels to enclose the timber frame structure. One of the bits was filmed at the panel manufacturing plant. Bascially a sheet of OSB and a sheet of drywall held apart and then they sprayed a 2-part foam between them, which expanded and bonded to the sheets.

In theory, a serious DIY'er could build a jig to hold the panels apart and spray foam in between them. I'm guessing the jig would need to be well reinforced to make sure the sheels don't blow out while the foam is expanding... and maybe rigging up some sort of mulit-head sprayer for even distribution... but even then, I'd still be concerned about voids and I'm not sure where to get the the 2-part foam.
Jan. 31, 2011 7:46 p.m. S2 New Reader

Yeah, polyiso is pretty spendy. Most SIPS are out of polystyrene and make them thicker to meet the R-values, as someone pointed out, but they're still dang spendy. Ian F points out some of my concerns with bonding, but if you made those doors out of ~5" of polyiso, you've at least got experience with the stuff in a structural fashion so you've got a good idea of what you need (missed it in your first post). I've missed out on the tours of local SIPS plants, so I can't shed any light there. Did you hit up instructables and youtube- the only places I can think of off hand that might have some DIY goodness like you're seeking? Good luck- if you find it, hot link it
Feb. 1, 2011 8:41 a.m. SVreX SuperDork

SIPs= Structural Insulated Panels.

Without proper engineering, you are missing the structural part.

Don't mean to be a naysayer, but homebuilt SIPs will NEVER fly for any application connected with the building code.

Officially, the code is applicable to the entire country, although it is obviously enforced differently (or not at all) in different locales.

You won't be able to use them in any place that gets inspected, in any application that includes bank financing, and you take a significant legal risk for any other applications. If the panels ever had a structural failure (even after you've sold it), you would most certainly be liable with or without local inspection requirements. You could also have a lawsuit related to Sick Building Syndrome if the insulating material off-gasses, or seals the structure too tightly without air-to-air transfer.

The problem is the long term performance of the various adhesives and the off-gassing of the insulating products, as well as the load bearing capacity of the OSB faces without proper engineering.

Love the idea- I don't think you can do it unless you have an engineering license.
Feb. 1, 2011 9:09 a.m. minimac SuperDork

SVreX wrote:

..... Sick Building Syndrome if the insulating material off-gasses, or seals the structure too tightly without air-to-air transfer.

The problem is the long term performance of the various adhesives and the off-gassing of the insulating products, as well as ...... the OSB .

This is a concern with a lot of construction ideas. When I built our previous house, the material off gases could be smelled (as fumes)every time the gas range was used. It was such a problem, we even had the utility out to make sure there weren't any leaks.It just flat out smelled bad for about a month and a half. Between the OSB(side walls only), the adhesives (used on plywood sub floor and countertops)and the stains and finishes on the wood work, we had a very sick house. It was fairly airtight and utility costs were relatively low, but we often wondered if we were poisoning ourselves. I'd be willing to try a DIY S.I.P. structure for a shed maybe, but not much else.
Feb. 1, 2011 9:17 a.m. SVreX SuperDork

Officially, a shed is not a house, and therefore is not subject to the Uniform Residential Building Code.

The op asked about a small house. That IS subject to the building code.
Feb. 1, 2011 9:32 a.m. alfadriver SuperDork

Ian F wrote:

I remember some 25 years ago when This Old House did the famous barn-reconstruction project where the used foam panels to enclose the timber frame structure. One of the bits was filmed at the panel manufacturing plant. Bascially a sheet of OSB and a sheet of drywall held apart and then they sprayed a 2-part foam between them, which expanded and bonded to the sheets.

In theory, a serious DIY'er could build a jig to hold the panels apart and spray foam in between them. I'm guessing the jig would need to be well reinforced to make sure the sheels don't blow out while the foam is expanding... and maybe rigging up some sort of mulit-head sprayer for even distribution... but even then, I'd still be concerned about voids and I'm not sure where to get the the 2-part foam.

I remember the same show, and one extra detail- after the foam was sprayed in, and the two sheets of OSB made an oreo, the part was then sent to a series of rollers- to conain the expansion, and increase the structural properties of the parts. It was tons of pressure that the rollers applied to the parts to contain the expansion.

Then the parts were "machined" so that they would fit together and/or connect with the beams.

I'd be more worried about this part of the process before the off gas. Seems like a very important step.

I've seen ads for the foam before- car people would use the slower two part foam to put into car voids to stiffen the car up. Works pretty well.

I know for sure that the spray bottles of foam you get at the hardware store are not even close to being structural. But don't know if the two part insulation can be.
Feb. 1, 2011 11:33 a.m. Ian F SuperDork

SVreX has a good point. Inspections for an occupied structure happen at various points during the construction: open framing being one of the major ones. A discussion with the local inspector would be the first task. Most are not opposed to new high-efficiency technologies, although they do tend to get testy when it's a surprise.

One thing and the TOH barn project is those panels were not really the structure of the house - the timber frame was. And they installed an air-air heat exchanger for air quality since the house was so tightly sealed.
Feb. 1, 2011 12:07 p.m. SVreX SuperDork

SIPs by definition are the structure. The OSB is the structural component.

The TOH episode was not the same. Those were laminated insulating panels (sheetrock on the inside). The structure was built by Benson Woodworking. They have in-house engineering of SIPs, and are licensed for shipping the components to multiple jurisdictions (utilize third party engineering firm certification). (I've done a lot of timber framing, been to their plant). Yes, they also have high pressure rollers.

The building code allows for SIPs, but not without engineering. That's what the local building inspector will tell you.

The uncontrolled manufacturing technique will rule it out for code compliance.