Permanent adhesives for polyiso?

[ken winston caine]

Am experimenting with building an H18 from 4" thick polyiso for a permanent, "tiny home" fixed-location install.

Want to find the right adhesive to permanently adhere the beveled edge, polyiso to polyiso.

Anyone found a great one?

Have, in the past, done small tests with a few adhesives. Found asphalt emulsion to work, but it's messy, odorous, and can't be painted over where it squishes out.

Liquid Nails makes an adhesive it recommends for both polyiso and Styrofoam, but am not finding it locally. I read that R-Max recommends the readily available "Heavy Construction" formula of Liquid Nails. Picked up a tube of that and may today, weather permitting, test it on repairing a broken 4x8 4" board of polyiso.

Seeking others' experience with effective, STRONG, PERMANENT adhesives for adhering polyiso to polyiso.

Thanks, Dylan, for suggesting I open a new thread for this,

[dave rhode]

recommend epoxy resin, at least for the foam > foam joint. It cures without needing air. It also doesn't melt the foam.you will never break the bond once it cures.

i experimented with 4-5 different adhesives for an art project involving 10 layers of polyiso. you may be able to find something cheaper though.

[dave rhode]

Also, for your application, i highly recommend you look into building codes and use a non-flammable adhesive. I'm sure you don't want another grenfell tower disaster (they used same polyiso boards as hexayurts). at the least seal the seams and you probably want to add a layer of sheet rock on the inside. With 4" panels and glue you won't be able to kick your way out of a fire and escape the fumes.

[ken winston caine]

Thanks, Dave. Will price epoxy today.

[ken winston caine]

http://m.ebay.com/itm/Crystal-Clear-Bar-Table-Top-Epoxy-Resin-For-Coating-Wood-Tabletop-1-Gallon-Kit/231164299998?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20161006002618%26meid%3Df9b732533fc44de59f2e2ebb16a764a4%26pid%3D100694%26rk%3D11%26rkt%3D30%26mehot%3Dpp%26sd%3D281756320926&_trksid=p2385738.c100694.m4598

Would this work, Dave?

And please say more about what you mean by "seal the seams." In what manner?

Thank you.

<Snip>

[ken winston caine]

If my math is right, on an H18 design, I would have 118.6 square feet of foam-to-foam edges to attach (with my 4" thick polyiso). That would take 5 gallons of epoxy, it looks like. And that is way out of my budget.

So .... think I am going to run another test with asphalt emulsion. Last time I tested it was with small pieces of foam in 2011. They grabbed together beautifully and would not come apart and I saw no deterioration of the foam over a few weeks. Think I tossed the test pieces after about a year. They firmly held together through freeze and desert summer heat. That may be what I go with for this experimental housing project of mine. Really need to hold the costs down. 

Have about 4 gallons of asphalt emulsion on hand and think that in 2017 it is selling for somewhere around $40 per bucket (is that 4.5 gallons now) at home improvement centers. So it is certainly affordable.

Need to have this figured out within about a week when I expect to be putting together the roof and then rubber coating it. Have to get the roof coating done before about Sept. 1 when the seasons change here in northern New Mexico (usually within a week of Sept. 1 night temps drop 20 or more degrees). The roof coating has to be applied while nighttime temps are 60 or above. So I'm pressed for time to get that part of the project assembled and finished.

Am open to other suggestions for an adhesive, but I really don't want to spend more than about $100 to cover the 119 square feet.

[ken winston caine]

Cheapest I have found epoxy this afternoon is for about $100 per gallon of resin and gallon of hardner. I may be looking in the wrong places. If someone knows of it for substantially less, please share.

[Wolf]

Using asphalt as a glue is a fascinating idea. The first caveat that comes to mind is the potential britlleness of cured asphalt under cold extremes. Yes I see you had a test piece that stayed together, but did you have it under load or apply dynamic stress to it when it was exposed to your coldest outdoor temperatures? I am assuming your yurt will be exposed to buffeting winds, heavy rains, possibly snowpack. Will asphalt or coal tar maintain the shear strength necessary to keep your yurt upright or will it crack and allow joints to fail?

Likely there are reasons why tar isn't used as a glue for building construction and epoxy is. 

As a side note, since your application is using a fairly thick polyiso sheet, have you considered using wood joinery techniques like biscuits, mortise-and-tenon, or pegging to attach your sheets together? Using epoxy just on these smaller joint pieces would not require gallons of expensive glue. And maybe used in conjunction with the asphalt to seal the edges would be a workable solution.

--Wolf

On Monday, August 14, 2017 at 7:00:25 PM UTC-7, ken winston caine wrote:

...

So .... think I am going to run another test with asphalt emulsion. Last time I tested it was with small pieces of foam in 2011. They grabbed together beautifully and would not come apart and I saw no deterioration of the foam over a few weeks. Think I tossed the test pieces after about a year. They firmly held together through freeze and desert summer heat. That may be what I go with for this experimental housing project of mine. Really need to hold the costs down. 

...

[ken winston caine]

Valid concerns. And I do not have answers. Have wondered about its load-bearing ability as an adhesive. Do know the Chumash were have said to have used it to waterproof and help bond the canoes they rowed between the mainland and the Channel Islands.

We do have really powerful spring windstorms here. And occasional extreme snowloads. (4' in 2007. VERY rare. No idea if the 4" polyiso panels could stand up to that weight.)

The H18 essentially is a tension structure. If the tension ring is adequate (and I may do both top and bottom ones), even if the bond on a panel or two broke, wouldn't the building tend to hold together?

This is an experiment.

I remember back in the very early days of this group someone built a model and reported that it failed under winter snowload. But they provided few specifics. No idea what thickness of polyiso they used. And someone else reported that an OSB version failed under snowload. Again, no details on how it was constructed.

So ... I am aware the thing may fail. 

And I am aware that I know very little about construction and engineering. Suppose I will know a little bit more when this project is done. And even more after a few years if it manages to still be standing and livable.

And ... I expect that I will innovate a number of modifications and fixes along the way if this thing holds up well enough to allow that.

On Tuesday, August 15, 2017 at 11:15:56 AM UTC-6, Wolf wrote:

Using asphalt as a glue is a fascinating idea. The first caveat that comes to mind is the potential britlleness of cured asphalt under cold extremes. Yes I see you had a test piece that stayed together, but did you have it under load or apply dynamic stress to it when it was exposed to your coldest outdoor temperatures? I am assuming your yurt will be exposed to buffeting winds, heavy rains, possibly snowpack. Will asphalt or coal tar maintain the shear strength necessary to keep your yurt upright or will it crack and allow joints to fail?

Likely there are reasons why tar isn't used as a glue for building construction and epoxy is. <snip.

[ken winston caine]

Posted this also under "The Story of My Liquid Nails Fail." But is relevant here as well.

REVISION: LIQUID NAILS SUCCESS

NEW TEST: Liquid Nails vs. Epoxy

-1- Liquid Nails, spread thinly with putty knife, on smooth flat beveled-cut surface, with some tiny holes scratched into both facing surfaces with a wallpaper scouring tool, then clamped and cured for 24 hours, works BEAUTIFULLY! Incredible strength. And Liquid Nails *claims* its repairs will outlast the life of the original material. Am going to trust that it will last for my purposes. 

-2- Epoxy, surfaces prepared the same way as above and spread evenly over entire face, simply did not dig in to anything but the utter topmost layer of polyiso fuzz. And the adhered parts easily snapped apart after 24 hours cure time. When snapped apart, I observed the epoxy "bond" covered with maybe 1/100 inch of polyiso fuzz. Is possible that if I had punched a lot of tiny 1/2" deep holes in each face and smeared on the epoxy much thicker to fill those punched holes, that I would have gotten a stronger bond. But, given the positive results with the Liquid Nails, once spread with a putty knife, and its *substantially* lower cost, I am not going to do any further testing with epoxy resin at this time. Also is possible that epoxy would work with NEW polyiso boards. Mine are salvaged boards, possibly 20 or more years old. (They do age, outgas, lose R-Factor over time. And maybe mine are fuzzier along my cuts than new boards would be. I don't know.)

So ... I am going with the much less expensive Liquid Nails for my project.

That means I must create some 30-degree-angle braces (out of 2x4s?) that I can clamp onto roof-cone sections as I glue them to hold the adhered parts together tightly for the 24 hours cure time. And created 30-degree-angle braces for the wall sections.

As an additional measure, am going to use an awl to punch a dozen or more 1/4" deep random holes along each face to be adhered to allow for much greater material penetration in those spot, expecting that will make for a stronger, more durable bond once cured.

Also, am going to test using rubbing alcohol or acetone on a cloth to lightly rub the surfaces to be joined to see if that will help clean away dusty fuzz. (Or whether it melts the polyiso.)

Additional observations regarding my earlier Liquid Nails fail:

Because I was attempting to reattach two broken pieces with very uneven faces, I was not able to smoothly smear Liquid Nails on the broken faces. But on smooth-cut bevels, it smears easily, evenly, with a putty knife despite its vicosity. In this latest test, I applied it to only one of the two surfaces to be joined. I don't recall for sure, but think I might have applied it to both surfaces of the broken pieces in the test that failed.

On Wednesday, August 16, 2017 at 2:54:31 PM UTC-6, ken winston caine wrote:

Fail was my fault. 

1. I didn't clamp the boards after gluing.

2. I thought a 70 lb. pallet would be adequate to keep a wind gust from causing a problem during overnight cure.

3. I had assumed the Liquid Nails compound would be less viscous and more grabby and  that I could spread/smear it over the entire surface of each face to join. Not possible. Instructions say to apply in a zig-zag design, so that is what I tried. <snip>

[Steve Upstill]

Ken,

There are a lot of products under the Liquid Nails brand. Could you post a picture or an Amazon link to the one you used?

Thanks,

Steve

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[ken winston caine]

Steve: I guess I moved my followups on this to "The Story of My Liquid Nails Fail" thread. Is a photo of the tube there.

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