Are there things I have to keep in mind when building with ICFs?

No doubt the concrete core is solid but the insulation worries me a bit.

Please scroll down halfway down the page. http://www.quadlock.com/insulated-concrete-forms/panels.htm

The R50 wall has a lot of insulation. How am I going to attach things to it? The orange part is over 11" thick. That requires very long bolts to attach something heavy like a sunshade. (not to mention the bolts bending)

My question is: "Does a ICF house require a special floor plan?" If so what do I need to consider when designing? A fireplace and the insulation likely is a very bad combination, but what about a oven? Kitchen cabinets bolted to a wall? Do I need to move all those things to an interior wall

The fastening strips embedded in the walls should be plenty for any normal interior attachments, such as wall cabinets. Any kind of structural element, such as floor ledgers have to have direct concrete contact, so usually the foam is cleared away at the attachment points prior to filling the forms, so the concrete can come to the surface. I'm not sure about something like a sunshade. I don't think the weight would be a factor, but you don't want the wind ripping it off.

Those are really, really thick walls. I'm not sure there would be much of a pay-off in your climate. You should run the numbers to see what the BTU loss is versus a more normal R-24 ICF wall. By the time you factor in windows and doors, that R-59 takes a pretty big hit anyway. My walls are 'only' 12" thick, and I made flared window returns to reduce the tunnel effect.

Yeah the walls are really think. I'm trying to familiarize myself with BEopt to find sensible values.
Besides of that my questions are valid ones I think.
Are those fastening strips at standard locations or do the need to be 'placed' befofe pouring concrete?
If at standardized places it limits the locations I can fasten my things.

Yeah, finding and securing to the "fastening strips" are a problem that never quite goes away. My best solution was to use a hot knife with a box-shaped cutter blade to cut channels in the foam insulation. Then, I bolted treated lumber ripped to match the depth of the foam insulation directly to the concrete wall.

That unfortunately creates thermal bridges.
Where I live about everything is cavity walls an piping (water, electric) is all in the wall. But that obviously isn't a option with ICF because it makes the R value drop because there is quite a bit of piping in a modern house.
How is that usually done with ICFs?
Wooden framework?

As far as finding the fastening strips later I wanted to have something to attach my floor trim so I ripped a section of OSB shorter than the trim and fastened it to the ICF interior walls at the bottom. I then set the drywall on top of them. While I was mounting the OSB I used a permanent marker to mark the strip locations. Anytime I want to fasten something heavy to the wall now all I have to do is pull the trim to find the locations.

As far as plumbing I didn't run any lines in the outside walls. In my area it is poor practice anyway. The only line set that wanted to be on an outside wall was the kitchen sink (I like a window over my sink), I just ran the lines up inside the cabinet. About the only place I could see it being a problem is if you wanted to put a shower unit in the outside corner of a building, in that case I would just stud the wall out.

Shower units on exterior walls are definitely a problem. Most shower valves are made for walls with 4" depth and you don't have that with standard ICF. Avoid it.

Assuming a shower unit has at least 2 walls (corner unit) or 3 walls, you can put a shower on the outside wall as long as the wall with the shower valve and shower head are against on interior wall - I've got three installed this way.  There really is no feasible way to put the shower valve on the outside ICF wall, even if you furred it out with 2x4's to creat a cavity, because the plumber has to have access to the back of the valve to make the connections.

I have no plumbing in my exterior ICF walls other than through-wall penetrations for water supply and outside water faucetts.  All of my drain, waste, and vent (DWV) system is plumbed through interior 2x4 or 2x6 walls.  Plumbing code requires at least one (1) 3" stack vent through the roof and if this vent runs through an interior wall, a 2x6 or other thicker wall is needed to accomodate the 3.5" OD pipe.  My kitchen sink is on a peninsula attached to an interior wall with the water supply and DWV run through the interior wall.  The kitchen sink faces the breakfast area which has a wall of windows on the south and east side (east side partially shaded by a covered porch).  There are many ways to do this.  You just have to be aware of the limitations with ICF walls and plan ahead.

Posted By NewHoosier on 25 Nov 2014 09:36 AM
That unfortunately creates thermal bridges. 

Sometimes strength trumps insulation value.  You don't want your cabinets falling off the wall when you load them up with dishes (they can get quite heavy). 

If you have a lot of cabinets on exterior ICF walls, you might look into installing 1x4 furring strips from floor to ceiling every 16" on-center attached to the ICF screw tabs at least every 2'.  This would provide the strength needed to support the cabinets without compromising the wall insulation value.   All you would loose is 3/4" from the room interior dimensions due to the 1x4 thickness.

Sometimes strength trumps insulation value. You don't want your cabinets falling off the wall when you load them up with dishes (they can get quite heavy).

Don't worry, I'm the overdimensioning type
:-)


The furring strips I don't fully understand. Where exactly are they located? On top of the insulation or is there a little space between the strips and the insulation? The reason I ask is that I obviously want to some sort of wall in front of the insulation. For me such a wall would serve two or even three purposes. It just looks a whole lot better, a space to put wiring (electric, network, TV, etc) in. I might even fill it with some cheap glass fiber bats for a few extra R.

My point is that with adding that extra wall I create a distance between the furring strips and the outside of my interior wall. And by doing that the problem the furring strips fixed is reintroduced.
I think that's a bit advantage of cavity wall. They are worry free. You can hang heavy stuff where you like. Put all sorts of piping in it without having to worry about anything.

Posted By arkie6 on 25 Nov 2014 07:21 PM
There really is no feasible way to put the shower valve on the outside ICF wall, even if you furred it out with 2x4's to creat a cavity, because the plumber has to have access to the back of the valve to make the connections.

Here all connections are made before the wall is finished. The valve is screwed on later and can be replaced without any plumbing. http://www.deltaline.nl/media/2035/07019.37.png

Posted By arkie6 on 25 Nov 2014 07:21 PM

I have no plumbing in my exterior ICF walls other than through-wall penetrations for water supply and outside water faucetts.  All of my drain, waste, and vent (DWV) system is plumbed through interior 2x4 or 2x6 walls.  Plumbing code requires at least one (1) 3" stack vent through the roof and if this vent runs through an interior wall, a 2x6 or other thicker wall is needed to accomodate the 3.5" OD pipe.  My kitchen sink is on a peninsula attached to an interior wall with the water supply and DWV run through the interior wall.  The kitchen sink faces the breakfast area which has a wall of windows on the south and east side (east side partially shaded by a covered porch).  There are many ways to do this.  You just have to be aware of the limitations with ICF walls and plan ahead.

Same here, during the design phase I eliminated all plumbing on exterior ICF walls. The plumbing is all located on interior wood frame walls.

My plumbing code allows for a side wall plumbing vent stack so in my design I have ZERO roof penetrations. The vent stack will run out a 2nd story gable wall. One has to keep it so many feet away from any windows/doors.

Polycrete Big Block has metal fastening strips. Far stronger than plastic. Published screw withdrawal tests (required for building code approval) tell the tale and are on the website for all to see and compare.

What's the gauge and width of the fastening strips?

1.25" X 22 gauge. Screw pull (withdrawal) average ultimate load 311 lbs; shear 375 lbs.As an interesting footnote, on 40% of the shear failures, the screw head pulled through the wood rather than the screw pulling out of the metal fastening strip.

22g is good. Is it electro-galvanized metal?
So, what's your preferred screw, coating and tip for that?
If screw heads are pulling through wood, has any work been done on getting a fastener with an expanded head?

Posted By BrucePolycrete on 26 Nov 2014 11:39 AM
Polycrete Big Block has metal fastening strips. Far stronger than plastic. Published screw withdrawal tests (required for building code approval) tell the tale and are on the website for all to see and compare.

Nudura lists their screw pullout average at 250 lbs. Nudura is used in commercial buildings and the plastic attachment strips have worked perfectly fine.

When attaching cabinets one can screw OSB into the wall and then use the OSB as the anchoring point for cabinets. The OSB will act as a load distribution point and give a larger surface area to screw into.

I just used the IKEA rail and put a screw into every strip (every 8"). I think the cabinets would come apart before the mount came off the wall. The block I used has plastic strips, and the pullout is on the order of 250 lb, so I don't think strength is an issue, you just need to make sure you hit them.

ICFHybrid, The screw heads only pulled through the wood during testing. I have never heard of it happening on a Polycrete wall in the real world. If it's a concern, a washer would solve the problem. This is a #8 self-tapping screw with a coarse thread. And yes, the metal fastening strip is electro-galvanized. If you're interested, the full details including testing protocol with detailed charts and photos are on the PolycreteUSA dot com website on the page called "Technical Stuff". Lbear, the 250lb you quoted leaves the Polycrete attachment strip 24% stronger. Truth is, the real common problem with the plastic strips in the field is stripping them out and spinning the screw. Much tougher to do that in metal.

Posted By BrucePolycrete on 27 Nov 2014 05:59 PM
 Lbear, the 250lb you quoted leaves the Polycrete attachment strip 24% stronger. Truth is, the real common problem with the plastic strips in the field is stripping them out and spinning the screw. Much tougher to do that in metal.

I've never heard of the plastic strips being a problem so making them 24% stronger is creating a solution for a problem that doesn't exist.

I would disagree that stripping screws in metal is tougher to do in metal strips. How many screw threads are you able to cut into 22 gauge metal? Two thread cuts?

With the plastic strips in ICF one just has to set the screw gun to a lower speed and lower torque. High speeds and high torque is the problem. The high speed creates heat which melts the plastic and the high torque strips the threads.