So I had posted a few months ago asking about ICF for a farmstead creamery, and got a lot of helpful feedback. Now have a question specific to the interior finish.

I had been thinking using FRP, or more recently came across NuPlank which was installed in a neighbors cheese plant. Talking with a contractor though, I hadn't realized at first that these would require drywall as a fire barrier between the panels and the foam. These products, I think, run around $1 on the low end to $2 on the high for the material, and while I gather drywall is not very expensive, it will be in a rather wet environment. Another builder asked about just doing drywall and giving a really good layer of exterior paint, but I think long term that would not hold up well.

Wondering then how products like PermaCrete and PlasterMax might compare in this situation, price-wise and long term durability. The finish does need to be smooth. Since I'm not really comparing these products simply to painted drywall in this situation, but rather to drywall topped with FRPs or vinyl, I image it should be more cost comparable? It would be a matter of spraying or troweling the product, then painting. Would products like these handle well washing and spray-downs and high humidity? Any thoughts from experienced users would be appreciated, or recommendations for yet other options as well. Stainless steel (probably expensive!)? Tile (any more/less work and product than PermaCrete or PlasterMax)?

Another option, probably fairly costly but very water tight and durable, would be to put Kerdi waterproofing membrane and tile. Check it out at http://www.schluter.com/143.aspx. The product is intended for showers, saunas, and such but would work real good for what you need, I believe. You might even be able to cover the Kerdi membrane with something other than tile for less cost and still have a good waterproof surface.

I used it for my showers. The membrane is so waterproof it is applied to ordinary drywall.

Posted By dmaceld on 17 Apr 2013 01:32 AM
Another option, probably fairly costly but very water tight and durable, would be to put Kerdi waterproofing membrane and tile. Check it out at http://www.schluter.com/143.aspx. The product is intended for showers, saunas, and such but would work real good for what you need, I believe. You might even be able to cover the Kerdi membrane with something other than tile for less cost and still have a good waterproof surface.

I used it for my showers. The membrane is so waterproof it is applied to ordinary drywall.

Schluter seems to make pretty good waterproofing products (at least from my research).  I will be using their Ditra product for waterproofing my 2nd floor balconies over occupied space.  It is also a decoupling membrane, so it allows for more movement between the the concrete deck (insuldeck) and porcelain tile I will be putting on top. 

They do have some pretty good videos on their site if you check it out.

We have used acrylic stucco on the inside for service garages in the automotive trade. It meets the requirement of a thermal barrier and is washable. Just use the finest texture you can get.

FBBP acrylic stucco does not have a fire rating and is for exterior use only. If you want a thermal barrier, washable and fire resistant coating StuccoMax is the answer

Posted By ICFcoatings on 18 Apr 2013 09:15 AM
FBBP acrylic stucco does not have a fire rating and is for exterior use only. If you want a thermal barrier, washable and fire resistant coating StuccoMax is the answer

Why do you say that? It has enough cement in it to provide the thermal barrier and I have seen nothing to indicate that it is hazardous so why not inside?
I have two car dealerships in Alberta that it was approved for in the past five years.

Have you considered Magnesium Board? I have never used the product, but from my research they should have no problem handling the moisture and meeting thermal barrier requirements.

Here is another option:

1. Screw 1/2" x 3' x 5' Durock cement tile baker board panels to the ICF. They cost ~$11 each or ~$0.73/sq ft.
2. Seal joints in cement board with cement and Durock fiberglass tile backer tape designed for cement board tile underlayment. Figure ~$0.10/sq ft for screws and fiberglass tape.
3. Parge the cement board with a ~1/8" thick coating of fiber reinforced surface bonding cement. Quikrete Quickwall cost ~$17 for 50 lb and covers ~50 sq ft @ 1/8" thick or ~$0.34/sq ft. Can get in grey or white or other colors.
4. The surface bonding cement provides a pretty good water resistant surface; however, if you want it to be waterproof, you can seal the cured cement coating with a silicate sealer such as RadonSeal. 5 gallons cost $165 and covers 1000 sq ft or ~$0.17/sq ft.

Total material cost ~$1.35/sq ft.

I've got a wood framed wall covered with OSB and 30# roofing felt that is behind my garage and under a covered porch that I intend to use this Durock cement board and surface bonding cement approach to covering.

Posted By ICFcoatings on 18 Apr 2013 09:15 AM
FBBP acrylic stucco does not have a fire rating and is for exterior use only. If you want a thermal barrier, washable and fire resistant coating StuccoMax is the answer

ICFcoatings, why StuccoMax rather than PlasterMax? Just curious.