Hi everybody, we built an ICF (Nudura) house over 5 years ago in Ontario. Passive solar design, wood furnace, traditional stucco, slab on Hambro. Very happy with it. However, it looks that we will start all over again, so I wonder if you guys can suggest a better technology than ICF, that maybe developed during the last years. Thanks!

Kind of dumb to go on an ICF forum full of passionate ICF aficionados and ask for something different, dontcha think, Einstein?

Beno,
We are currently building an ICF home with Nudura blocks as well. When we started our research in 2012 we found that ICF was the best technology then and still is. We haven't seen or heard about a better technology and I constantly do have my eyes and ears open for improved building methods and systems. But in regards to energy efficient, sound proofed walls, versatility and durability and fire proved material I think ICF is among the best for walls. I am a fan of ICF and would talk about the advantages to anybody who wants to listen to me, nevertheless I would not have a problem to say something different if I knew of something better.

I don't think that there is one 'best' system for every location. I think ICF is a little weak on R-factor for very cold climates, at least for most blocks. ICF works very well in our mild SC climate, and I like the strength and sound-proofing, but at R-24, you could do much better where higher insulation factors are needed/wanted.

I love ICF and after 5 years in an ICF home I know its advantages. However, I'd prefer a system where the foam is inside the concrete wall. The foam is a fire hazard, and is much easier to apply traditional stucco directly on the concrete.

Not to be confrontational, but to correct Beno's misconception, no EPS foam used in insulated concrete forms in the USA and Canada is a "fire hazard." It is required to contain a fire suppression agent and must pass strict performance guidelines with regard to flame spread and smoke generation. In fact, in most cases, the EPS will not ever ignite. The smoke generated by EPS in a fire is typically less toxic than wood smoke. With regard to beno's opinion on stucco application, it's a standard practice all over North America to apply stucco finishes over EPS insulation -- not just on ICF buildings.

If you want to increase your R-value with ICF, Nudura has released their Plus-Series product since you last used their product. They have some info on their website, but it can increase the R-value of Nudura forms to R-48 (true R-value, not equivalent).

ICFbdr has a good point. Polycrete has developed the R-Stak, which allows you to increase the total EPS thickness on your ICF wall to 23" on a 6" wall. That's an actual R-value of 96.6. Why anyone would want that much is beyond me, but it is the maximum thickness within our manufacturing capability. More common are 7.5" and 9" which yield actual R values of 31.5 and 37.8 respectively.

I have done extensive research on ICF, geothermal, impact resistant windows, SIP, etc and have come to the conclusion that nothing to date beats ICF. I am building in 3 months with Nudura and currently living in a Hebel home to include concrete lightened ceiling. If there was something out there that was practical and met code I would be all over it. Living in a concrete bunker with thermal mass allows for low electric bills (Florida panhandle location).
I don't know the cost of Nudrua in R48 configuration but the current 2 /58" EPS on each side is sufficient for my needs.
You never said what your requirements were for better?
I am an engineer and to me defining my requirements gives me direction regarding what I want. For example how good are your windows going to be and how many, doors how good, ceiling assuming stick construction how well is it insulated and sealed...

Please post what you do regarding your new home. I plan to post my construction to benefit this forum for future readers that might be interested in one of the technologies I am employing in my house...

Posted By beno on 10 Sep 2014 07:54 AM
I love ICF and after 5 years in an ICF home I know its advantages. However, I'd prefer a system where the foam is inside the concrete wall. The foam is a fire hazard, and is much easier to apply traditional stucco directly on the concrete.

What you are looking for exists, and it called SCIP (Structural Concrete Insulated Panel).  The wall cores are typically EPS (in a number of thicknesses with wire-reinforced concrete on both sides of the EPS (with steel ties between the skins on some spacing, but not so much that it's a huge thermal bridge.)

The concrete is typically sprayed rather than poured (similar to how swimming pools are often done), and usually textured as the scratch coat for hard-plaster on the interior, and stucco on the exterior.)









SCIP roofs typically involve some amount of rebar or light channel iron type reinforcement, but it's possible to build with fairly continuous EPS on all sides of the structure from sub-slab to roof ridge and very low thermal bridging.

SCIP is a very good way to build in hurricane zones when you make the roof SCIP as well, since you end up with a steel reinforced concrete monocoque as the building shell which cannot be torn apart by the wind.  The R-values can also be dialed down to something appropriate for warmer climates as well. 

An R22 mass-wall such as ICF in Florida is great and all, but totally overkill, given that even R6 would meet IRC 2012 code min. with 50% or more of the insulation outside the concrete.  In cooling dominated climates a 3"  (~R12) SCIP would usually meet or beat an R22 ICF on thermal performance, since there is more thermal mass fully inside the thermal envelope to manage the diurnal cooling loads from window gains, etc.  In heating dominated climates you'd want more R than that, but it's possible to build SCIPs with even 12" EPS (R50 steady-state for just the foam without using any fuzzy dynamic-performance R-equivalent type numbers.)

There are multiple vendors, of this stuff.

You sure that meets US building codes? looks like a way to build in a 3rd wrld country. That chicken wire the structural part?

Posted By Leon Possible on 10 Sep 2014 03:35 PM
You sure that meets US building codes? looks like a way to build in a 3rd wrld country. That chicken wire the structural part?

SCIP technology was invented in the US, and there have been SCIP buildings from Texas to  Hawaii to Florida to Oregon.  The wire is part of the structural aspect, just as re-bar is required in heavier concrete, but the monocoque nature of both individual panels and the full house gives it a great deal of structure.

It's at LEAST as structural as OSB-clad EPS core SIPs- it doesn't have the inherent weaknesses at the seams, since the wire from one panel to the next get tied together prior to adding the shot-crete. An inch or two of wire-reinforced shot crete is quite rigid, and when bonded to an EPS core (and to the concrete on each side of the EPS, via the through-wires) the thing is as good or better than a 4" rebar reinforced concrete wall.

The wire reinforcement is significantly heavier than chicken wire, and it's more hurricane proof,  fire proof, insect proof, and earthquake resistant than most other construction methods. The foam is completely encapsulated in concrete when you're done, and there are two thin concrete monocoques mechanically coupled with EPS and wire.

It's not cheap- it depends on how hungry the shot-crete installers are in your neighborhood. In locations with lots of in-ground pool installers you probably have more competitive shot-crete installers than in say, Whitehorse Yukon, where not even crazy people are installing outdoor swimming pools.  In third world countries where labor is cheap the concrete can be mixed & applied by hand, but in the US & Canada that would be more expensive than hiring a swimming-pool shot-crete outfit to do that part.

Another option is a one-sided ICF (another product nudura recently released). You can have an ICF with bare concrete on one-side and EPS foam on the other.

Posted By Dana1 on 10 Sep 2014 04:45 PM

It's not cheap- it depends on how hungry the shot-crete installers are in your neighborhood.

It is very regional dependent. If you are in the Southeast US, then shotcrete and SCIPs are easier to attain. Before I decided on a wall assembly I priced out SCIPs and it was impossible to find anyone who could do shotcrete in my area. So when I priced it out to have a contractor from a SCIP company from California come out, it was priced out to around $25+ per square foot of wall space. So yes, it is not cheap.

The other obstacle was code approval. As far as I know, the IRC/IBC does not recognize SCIP to the point where it would have its own section heading. ICF is recognized and does have its own code section. That may have changed since I researched it.

ORNL's limited study on SCIPs showed a 7-10% R-Value loss* due to the thermal bridging of the wire trusses.

* The trusses tested were stainless steel, which has a much lower thermal transfer vs. standard steel. So the thermal bridging would be worse with standard steel trusses.

 

I think that you refer to: http://www.nudura.com/divisions/nudura-products/one-series Looks interesting, but you loose half the insulation.

You could always combine the One-Series and the Plus Series to get as much insulation as you want on one side of the concrete.

I couldn't find this specified on the Nudura web site but I take your word for it. If I choose a form with no foam for exterior (keeping all the insulation inside), will I be able to apply a good stucco paint directly on the concrete outside? Will this affect negatively the thermal mass of the house? It is recommended to have the foam outside.

My current home has just that. Concrete Hebel with Stucco applied. Much easier to apply to raw concrete than most anything else. It is very common in Florida as most building are block construction along the coasts (Ft Meyer, Naples, etc building codes)...

It is best to keep the thermal mass inside the insulation. Why not go with an acrylic stucco and direct apply to the exterior of the ICF? Double check that this is allowed in your region, as some areas do required a drainage layer beneath any stucco.

Posted By beno on 10 Sep 2014 08:48 PM
I couldn't find this specified on the Nudura web site but I take your word for it. If I choose a form with no foam for exterior (keeping all the insulation inside), will I be able to apply a good stucco paint directly on the concrete outside? Will this affect negatively the thermal mass of the house? It is recommended to have the foam outside.

A mass wall in a cold climate with all of the thermal mass OUTSIDE the insulation has lower thermal performance than almost any other type of construction of equivalent whole-wall R.  Not only is it's performance worse than a symmetric ICF, it's worse than a low mass stick built wall of equal whole-wall R.  In a cooling dominated climate it's only slightly worse than a symmetric ICF.

If you put 100% of the thermal mass on the interior the thermal mass benefit is maximized, but if it ever gets too cool/warm it takes a lot longer to bring the place up/down to temperature.