Laminated SIPs?

[GPW]

Guys , we have been making laminated foam /ply structures for years and years ...WINGS ... thay have to be strong .... I would suggest making the frames(outsides/attachment points , etc.) first ... add the foam , and the Home Depot pink foam is fine as a structural component, or the Blue foam ...The white bead foam is not as good as the others , but will work , because the strength of the panels is in the skin, and the further apart the skins the stronger it will be (to a point , of course ) we used a contact cement for wing skins ... Southern Sorgum.. Was water based and did not eat the foam .... all other Contact cements eventually would eat the foam in the heat of the Sun ... Vacuum bagging is the way to go for these and is not that hard and produces superior results (and smooth surfaces.... Epoxy is a good adhesive , but heavy , and very expensive ... Pu glue and that expanding business may give you some trouble ...

I've been chided about over complicating my TD , seems like this might be a dead end street , for the same reason ... no real advantages over proper proven TD construction techniques....

I will however be willing to discuss at length , foam skinned structures, of which I have some experience...just not in TD's ...

[Artificer]

Foam Selection: I would stay away from expanded polystyrene (white bead board) because of the lack of strength. That leaves extruded polystyrene (blue or pink) foam board, or more expensive types. If you go with pink, its probably Foamular. Some of its properties are:
Type Comp Str. Flexural Str. Density (lb/ft^3)
150 15psi min 60psi min 1.4
250 25psi min. 75psi min. 1.8
400 40psi min. 115psi min. 2.04

Nowhere near the Corecell that John mentioned: (density of type a, 3.6lb/ft^3), then again... we're not trying to hold up a house. If you can get the Foamular 250, its higher strength is better. Its typically used under concrete for foundation insulation. Don't know if HD has it, but I've seen it at Menards, our reginal big box. Closest Menards to you is probably Jackson, MI. Most lumber yards should have, or be able to get the 250 for you. Last time I looked, it was $30/sheet vs $15/sheet for Foamular 150.

Glue selection: I used polyurethane glue to attach my insulation to my sides. I like its gap filling properties. I actually misted the side sheet before applying to induce the foaming. Elmers brand is less viscous than Gorila, and tends to foam more. I used a water based multi-purpose tile adhesive for my floor foam. I don't know how well its bonded, but I'm not really using it structurally.

As GPW said: the strength is in the skins. As long as the bond between the skins and foam is adequate, and the foam can take the stress, its good to go.

How are you going to use these panels? Standard SIP construction (one method) is to assemble the panels, cut the opening, gouge out the foam around the openings, and put blocking in. I think its easier to put the blocking and foam on, then apply the second skin.

Captainsam: check out U. S. Composites 80cu ft kit for $209 2lb/cu ft densit. Also, for your 4'x8' panel: I was think of how to clamp it, and came up with an idea using a self-propelled weight. Find a flat spot in the driveway, build a frame out of 2x10's and deck it with 3/4 plywood, put side one down, pour the foam, place second skin and deck on top, and drive the front of a car or truck on top of the frame. Kind of silly, but I've been thinking about this for a while. (my foam kit should be arriving today, so I get to play with the stuff )

[Dewayne_Mellen]

I was thinking about using the foam that you pour in. I had no idea on how much force the foam would apply while it was expanding so what I was thinking was to use 2x2 (or whatever) for the frame and add 1/4 inch plywood to each side. Leave the top board out of the frame so that you can pour the foam in. Stand the walls up and then drill holes into the frame boards and attach 2x2s with bolts throught them to each side horizontaly. You can then pour the foam into the cavities. When done remove the bolts and fill the holes with epoxy. Some website that I read said that polyurathane foam will stick to just about anything even itself so a wall doesn't have to be completely done at one time. Smal amounts of foam could be poured in, left to dry and then some more foam put in.

I don't know if I'm going to do this or not. I've been thinking about what I'm going to build for the last month or so after I got a pop-up camper that's in bad shape. The only constant to the design (which changes at least once a week) is that it's going to be for 4 people and my wife wants to be able to stand up and to be able to lean against something.

[mikeschn]

Dewayne,

Welcome to the forum...

4 people and stand up room... that's a tiny trailer for sure... Keep us posted on your design thoughts... there are lots of people looking for exactly what you just described...

Mike...

[Dewayne_Mellen]

When I was younger I traveled with my parents in a 13 foot scotty trailer with 5 people in it. I don't remember that trailer but my mom was telling me that people would line up to watch us come out because it looked like a clown car. People would want to see in just to see how we all fit into it. My dad had added to bunk beds for my brother and me about his and my mom's bed and then they had a board between their beds that my baby ister slept on. My dad said that one person would have to get up and then dressed and leave the trailer before the next person could get out of bed.

[Mark Mckeeman]

Hi,

I think Happitrails teardrops has us all scooped on this one.

I saw his site when I was researching SIPs about a year ago. I queried him ounce about where he got the panels and I think he said he made them. He's been building foam core aluminum/plywood laminate SIP walls for teardrops for a while now. Maybe someone will contact him for some DIY tips.

http://www.happitrails.com/

I never did find a vender for thin sip panels, say 3/4" - 2". There must be a manufacturer of commertial building materials. I see insulated aluminum and stainless covered architectural panels being applied to comercial buildings but I havn't found any source of info or specs.

Mark

[captainsam]

Cap'n, yes indeed we wanna see some pics and thanks for the info...this subject has been discussed before but hasn't really gone anywhere...I am sure there are others here who are as interested as I am to here your results
madjack

Well here goes. I took some pics of my sample SIPs to share. They are just rough experiments but they are stronger that I could have imagined. The polyurathane really bonds to the wood totally. The only way I could separate the sides of a small test panel was to fracture the foam.

FIRST TRY



This 2.5 inch thick SIP was made with two sheets 5.2mm Luan ( 12" X 12") held in a U-shaped frame while the polyurethane foam was poured into the verticle cavity. I lined the frame with waxed paper so it wouldn't stick. I sanded most of the paper off but it is still present. I just dampened the plywood and poured the foam into the three sided cavity. I cut the excess foam that came out the top off with a hand saw.

MORE AMBITIOUS



Here you see my first attempt again as well as a second attempt of larger scale. I wanted to see how I might fasten panels together so I built a sample joint between two 2' X 2' wall sections (now 3" of foam) to simulate the junction of two walls or a wall and a roof or floor. The bracing was 12" centers which is too close for real life. Probably 24" would do. I filled only half the structure with foam. This 3" foam R-22 wall fully filled would be weigh about 3 lbs. per sq.ft. of surface area as built including joints. The smaller sample without supports was about 2 per sq.ft.

STRUCTURE




I built stringers of luan and 1X1 strips (stringers glued with polyurethane glue and stapled) that extend a few inches past the plywood. This way the stringers can be joined to hold the panels together. This shows the unfilled cavity and stringer (I-beam).

EMPTY CAVITY


This shows the foam filled cavity next to the empty cavity. I didn't have enough foam to fill both. I built the structure. foamed one wall and put flexible poster paper around the open joint (where stringers meet I rounded their profile) and foamed the rest,. Then I pulled off the paper I had the rounded shape on the external corner. This would need fiberglass or some other covering.

OUTSIDE CORNER



This shows the external corner that needs some kind of covering. Fiberglass of aluminum flashing might work.

The way I joined the panels was just a hairbrained idea that may or may not be best.

Hope that's not too much band width to make the point. I really want to build a superinsulated camper that can function with very small HVAC loads in all climates. The 3 inches may be overkill, but two inches is probably ok.

Pros:

Insulation of about R-7 per inch

Extremely strong structure

Cons:

Price (40 cubic feet of foam is about $200). A 4' X 4' X 8' camper with 2" thick walls would be 27 cu ft and use close to that amount with waste)

Can be messy

Unproven- as homebuilt panels

The foam requires warm temps ( 70 degrees) to expand correctly so I have been on hold her awaiting spring. No, my wife said no way in the kitchen! I hope to fabricate some 4' X 8' panels that are 2" thick and see:

How strong they really are

How dimensionally accurate they can be built

How structually consistant they can be built

How much they weigh

How best to fasten them or use them in TTT construction

How long it takes to fabricate them

What they cost

I am also looking at a "pressed" luan-Foamula-R-luan panels bonded with gorilla glue (polyurethane). This would proably use vacuum bagging to press the panels with 7psi while curing.

That's what I've been up to. Any comments appreciated.

Sam

[Guy]

Dear Sam,

You are not going to be able to get away with vacumm bagging ureathane and still be making a SIP. You will just be making a IP. I will try and find some of the previous posts on the PSI requirments and the proper Adhesive for ureathane vs. stryrene.

[captainsam]

Dear Sam,

You are not going to be able to get away with vacumm bagging ureathane and still be making a SIP. You will just be making a IP. I will try and find some of the previous posts on the PSI requirments and the proper Adhesive for ureathane vs. stryrene.

Guy

Perhaps I didn't explain what I was planning clearly.

The panels that are "bagged" all use pre-formed EPS (Epanded Poly Styrene) or XPS (Extruded Polystyrene). EPS is white bead foam molded into sheets (and coffee cups) and has lower R-value than XPS. The XPS is the extruded Blueboard (or Pink) used as insulation for house sheathing. EPS is cheaper but weaker (compressive and shear) and less dimensionally consistant than XPS.

I want to explore how to bond facings of luan to both sides of the XPS using a polyurethane based adhesive to create the bond line. The Foamula-R ( see:http://www.owenscorning.com/around/insulation/products/foamular.asp) I referred to is a Pink XPS board made by Owens-Corning). This is how SIPS using OSB and Styrene foam (usually EPS) are made for home construction use. FoamulaR is XPS NOT Polyurethane.

Commercial polyurethane SIPS are made by introducing the foam between panels that are held dimensionally consistant while the foam expands-bonds and cures. There is no adhesive as the foam bonds directly to the facings. The machines cost big $$s.

I prefer the process I have described in my "show-and tell" in the previous post if it works, mostly since I think the bond to the core (foam) by the facings(luan) are fairly reliable and easily reproduced. It is also cheap to do, using no special equipment. I was only saying I would explore the "other" way to make sips to see what I could learn about the possibilities there too in case this trial failed.

But what do I know....this is an experiment for me and I am only armed by what I have learned about this process at the library and through Google. I am not trying to "press" urethane SIP panels though.

Thanks for your comments
Sam

[Artificer]

Captainsam,

This stuff probably looks familiar... We poured my roof foam this weekend. (2lb/ft^3, 2-part)



You're right about strong. This stuff is tenacious. The little mounds to the left in the picture were extra in the bucket of a previous pour. I'm impressed with the gripping strength and hardness of this stuff. With 1/4" outside skin, the bays of the teardrop are rock solid. Now that I have some of this stuff, I think I'll add it to the SIP test I'm probably going to do this week. (didn't get to it this weekend)

Now to finish the rest!

How did your volume calculations and foam expansion match? Did you just make extra? I found the foam didn't quite expand as much as it should. I think the desired temp was 75-80, and I was only around 68-70.

Michael

[captainsam]

Captainsam,

How did your volume calculations and foam expansion match? Did you just make extra? I found the foam didn't quite expand as much as it should. I think the desired temp was 75-80, and I was only around 68-70.

Michael

Looks good.

I agree completely about expansion ratio. I found more like 15-20 times expansion, not 25-35 as advertised. It was a cool fall day. I warmed the liquids to 80 degrees but the cavity walls were in the 60's so maybe that was part of the reduction.

I noticed you are pouring on the surface between the frame members and under what appears to be the roof skin.
Are you cutting the excess foam off flush or just closing the cavity and allowing the foam to expand to fill? If you overfill, where does the excess go? Could the pressure bow the skin out? I'm just not sure how you are doing this and I'm curious as I want to have a curved roof too.

Thanks
Sam

[Artificer]

I noticed you are pouring on the surface between the frame members and under what appears to be the roof skin.
Are you cutting the excess foam off flush or just closing the cavity and allowing the foam to expand to fill? If you overfill, where does the excess go? Could the pressure bow the skin out? I'm just not sure how you are doing this and I'm curious as I want to have a curved roof too.

Just closing the cavity. That way the foam bonds to both skins.

The procedure I used: apply glue to first bay, and staple plywood across the bottom edge. Make sure everything is ready, mix, and pour into crack exposing the cavity. Bend plywood and staple shut. Wait to see if its filled.

I have 1/2" holes drilled through the center of spars, 6" on center. It lets me check the fill level. The idea was that it would allow pressure to be relieved. The calculated foam amount never seemed to fill the bay. Some of the second bays foam dripped trough the holes, however, so I think I've gotten a decent fill. I'll probably drill some inspection holes in the exterior skin. If necesary, I'll use great stuff to finish the fill. The tube should allow me to get into the cracks. I'll have a painted exterior, so bondo and fiberglass patches are no problem.

My interior skin is 1/8" birtch, and the exterior is 1/4" maple. The 1/4" was a pain to bend, but didn't show any bowing, probably due to the curve. Didn'tn notice any bowing of the interior skin either. The two stage fill probably helped. After 20-30 minutes, the foam is hard and fairly strong. It can probably stand to be overfilled then.

This insulating method is slow, costly ($70 for my 8ft^3 kit w/shipping), and somewhat a pain to do. However... it has an extreamly high "coolnes factor" that I couldn't pass up, as well as making an VERY strong roof. I can probably dance on it without denting it.

If you're interested, I have a couple of ideas about your 4'x8' panels, and how to pour and brace them. Should give good dimensional stability for the price of a couple sheets of plywood and a dozen 2x6's.

Good luck on your testing.

[Guy]

Dear Capt.,

Here are two Adhesives for SIPs, from a previous thread:

Isocet or Isogrip adhesive frrom Ashland Chemical (the people who make Valvoline for those who do not know Ashland is one of the premeir construction materials manufacturers in the world).

Please note not all ureathane SIPs are made the Thermacore way, in fact, Thermacore is the exception, not the rule.

Here is the link to Ashland. http://www.ashchem.com/ascc/specialty/insulated.asp

Structural Insulated Panels

ISOSET® Adhesives
Water-based ISOSET adhesives use a two-part, emulsion polymer isocyanate technology to produce bonds with excellent creep, shear and tensile properties. Parts bonded with ISOSET adhesive are extremely durable and offer outstanding resistance to moisture and humidity. ISOSET adhesives have been specified for:

* engineered wood (I-joist, finger jointing, thick LVL)
* glucam
* structural foam-core panels
* hardwood flooring
* architectural and patio enclosures
* doors (fire-rated and lead-lined)
* millwork

ISOGRIP® Adhesives
ISOGRIP adhesives are one-part, 100-percent reactive, moisture-cured urethane adhesives, used for structural bonding of porous or non-porous substrates. For continuous process applications we offer catalyzed moisture-cured urethane adhesives that cure quickly. ISOGRIP has been specified for:

* exterior, structural load-bearing applications
* patio enclosures
* architectural panels
* foam-core panels
* refrigerator cooler panels
* exterior entry doors
* insulated garage door panels

[asianflava]

Isocet or Isogrip adhesive frrom Ashland Chemical (the people who make Valvoline for those who do not know Ashland is one of the premeir construction materials manufacturers in the world).

We use Ashland chemicals at work. We use so many, that we have Ashland staff onsite 24/7. They handle our chemicals, monitor the chemical delivery systems, etc. I don't know about the entire company but the part that we deal with, was bought by Air Products.

[GPW]

Gentlemen , all this talk reeks of "Mass Production" of TD's ... No one would go through all that to make specialized panels unless they're going into production (Mike ?) In that case , I'd like to point out the simpler approach ... mold aTD shell outta' the stuff Coleman canoes/ice chests are made of , spray insulation on , insert inner "finish interior " shell , bolt to frame .... <200lbs ... Cheap ... in the long run ...and how many canoes do you still see around .... mine from 20 years ago is still fine ....

even fiberglass , like boats(molds /chopper gun) would be easy for production .... Hey ? howcome you don''t see any TD's made like boats ???