We will likely be working with blocks that have a fixed thickness of EPS insulation on either side. On part of our building I did want to have more insulation, but we're already maxing out the size of the block with the amount of concrete we will use.
I wonder if it's reasonable to apply additional insulation to the exterior, such as 4x8 1" EPS panels. I was not sure how these would be fastened or glued to the outside. I've also never worked with wall construction before so I don't know if this would be an effective way of adding insulation. For example temperature might be transferred between or around the panels despite efforts to attach them securely to the ICF.
And, we don't care at all about appearance for this building, so I was thinking we might leave it at that and not use any exterior siding since it's an area without code enforcement. I know siding is a good idea to protect the insulation from flying objects and such, say during a storm. I wasn't sure if there was some other protection they needed, like from sunlight or harsh conditions.
Then it could even be finished off with ground contact plywood. In total it might be cheaper than vinyl.
Thanks

Edit: I think I might mean "XPS" panels- they are the ones that are easily bent and cut, with some effort, but pretty durable otherwise, and have a smooth, hard surface. Dow industries sells what I'm thinking of as Styrofoam (TM) Residential Sheathing Insulation, and they're blue.

From what I've seen with ICF, you normally don't apply more insulation EXTERIOR to the block.
What you do is you increase the core width, and they sell "plus panels" that you slide in INSIDE the form. Then, when you pour, the concrete presses them against the exterior face of the block.

And DO NOT simply leave the foam exposed!
The foam, and any sort of weatherproofing have definite limits on UV exposure. Usually about 6 months to a year.
After that, it starts breaking down.
Not to mention leaving it open for animal damage.

Don't be lazy, finish your walls. I've seen the byproduct of "We'll just put this off..."
It's a colossal waste of time and money.

Stole this image off the QuadLock site to demonstrate what I'm talking about with extra panels of insulation.

You can easily glue more insulation to the outside. I've done it on a couple of occasions. Used gum foam from JR Products, glued the extra reclaimed eps to the exterior with not many screws. The exterior was coated with concrete bonding cement which I think came in at about $.35 per sq ft. It installed with a cheap mason brush. Simple.

Thanks to you both.

From what I've seen with ICF, you normally don't apply more insulation EXTERIOR to the block.
What you do is you increase the core width, and they sell "plus panels" that you slide in INSIDE the form. Then, when you pour, the concrete presses them against the exterior face of the block.

And DO NOT simply leave the foam exposed!
The foam, and any sort of weatherproofing have definite limits on UV exposure. Usually about 6 months to a year.
After that, it starts breaking down.
Not to mention leaving it open for animal damage.

Don't be lazy, finish your walls. I've seen the byproduct of "We'll just put this off..."
It's a colossal waste of time and money.

The issue is money not work or laziness. We have also been considering Quadlock, and the flexibility with insulation thickness is definitely a plus.

You can easily glue more insulation to the outside. I've done it on a couple of occasions. Used gum foam from JR Products, glued the extra reclaimed eps to the exterior with not many screws. The exterior was coated with concrete bonding cement which I think came in at about $.35 per sq ft. It installed with a cheap mason brush. Simple.

Just so I understand correctly, you coated the ICF exterior with the bonding compound first, then placed the insulation product (the gum foam) on the coated exterior?
This gum foam functions as insulation?
Sorry, I'm new to all of this.

Basically you COULD use any exterior-rated, foam-safe construction adhesive to attach additional sheeting to the exterior.
One of the downsides is that you will be covering the exterior attachment strips in the ICF.
So be aware that this could become a hindrance in later stages of your build.

I'm generally leery of "tack-on" solutions for systemized setups like ICF for just this reason.
I'd be more inclined to figure out what my budget is, and then simply buy the best offered solution that fits within that budget.

No. We built an ICF building for a customer and he wanted more r-value as cheaply as possible. Found 3.25" eps from a reroof project at a really reasonable price. Having started my business career as an insulation contractor I knew that attaching the foam with a lot of screws would devalue the foam . So we installed it with the poly foam that you buy in 24 oz cans. Once the foam was dry we removed the screws and coated the surface with bonding cement. So you're not confused , we glued the sheets in place and then coated the surface with bonding cement.

We have done similar, i.e., use adhesive to add more EPS to exterior of ICF and then stucco the exterior surface. While I personally don’t trust depending on adhesive in SIP wall applications because a SIP failure would be a disaster, I am more comfortable using adhesive for this application as any failure (and we have not had any yet) would be repairable as structural integrity is still retained.

Posted By smartwall on 22 Oct 2019 12:23 PM
No. We built an ICF building for a customer and he wanted more r-value as cheaply as possible. Found 3.25" eps from a reroof project at a really reasonable price. Having started my business career as an insulation contractor I knew that attaching the foam with a lot of screws would devalue the foam . So we installed it with the poly foam that you buy in 24 oz cans. Once the foam was dry we removed the screws and coated the surface with bonding cement. So you're not confused , we glued the sheets in place and then coated the surface with bonding cement.

So did you use a product like the 24 ounce Great Stuff-Window and Door (low expansion) canned foam as a glue agent to attach the additional EPS to the outside ICF?

No actually the best product for gluing eps together is silcone

Posted By smartwall on 01 Nov 2023 08:20 PM
No actually the best product for gluing eps together is silcone

I thought silicone would melt the foam? Polyurethane spray can foam like Great Stuff glue is safer?

Silicone won't melt the foam. Holds much better thr poly foam. Should , lightly scuff the surface . Molding creates a surface film.

Posted By smartwall on 02 Nov 2023 02:47 PM
Silicone won't melt the foam. Holds much better thr poly foam. Should , lightly scuff the surface . Molding creates a surface film.

I will pick up some Gorilla Waterproof Caulk & Seal 100% Silicone Sealant tube and give it a shot. Is it a good idea to still mechanically attach the foam in some spots? I usually use the Wind-lock plastic 1.75" washer and screw and attach that to the ICF attachment strips to provide a mechanical connection.

I use the cheapest silicone caulk. A few screws are all you need until dry..