My builder is expressing concern about attaching Hardie Plank to the ICFs.  he suggested putting plywood up first and then attaching the Hardie Plank to the plywood.  The manufacturer of the ICF (TF System) says that the plywood may rot and recommends just attaching to ICF.  The builder thinks there will be gaps.  Any thoughts?

There should be no problem attaching the Hardie Plank directly to the ICF, you certainly don't need to use plywood first.

BUT.... Not all ICFs have continuous vertical mounting strips moulded into the blocks, so the first question is what block are you proposing to use?  If it doesn't have continuous vertical mounting strips then will your Hardie Planks be wide enough to locate the nailing points over a solid point? I doubt it.

How straight will your wall end up? Your comment about ply and your contractor indicate to me that he/she is not highly experienced in building with ICFs and that their ability to understand the need for bracing  means he will not end up with dead straight walls. Although HP is fairly flexible and should pull in to match the wall you may well end up with a wavy effect!

I either of the above cases you may well have to add Vertical 2 by 1 strips of treated timber (or metal high hat) to the wall to give you vertical nailing points to fix the HP to. If the wall is wavy you can add shims between the 2*1 and the ICF to true them.

If you have a block with an integrated vertical mounting strip and a contractor who is competent/takes the trouble & time to align and brace the ICF's before and during the pour then the HP can go straight on to the ICF with no problem.

I'd never heard of TF Systems  but now have Googled them and found their site at: tfinsulatedconcreteforms.com and their vertical panel system has  a continuous vertical fixing strip so you should have no problem. Just make sure your contractor understands the need to true up and brace the forms and not just rely on the top/bottom metal track and you should be good to go!

An inexperiened ICF installer may have a tough time with TF, as they can be tricky -- particularly in windy locations, so make sure he has been properly trained or (as I mentioned to you in another post) please hire a professsional installer. There are good installers in Montauk area.

First of all it will be no problem. Second, the topic of FC siding has been discussed many times the past couple of years on this forum. Here are links to several of those discussions where I've added my 2 cents worth. As you will quickly find out the only thing there is consensus on is it is no problem! Some even discuss TF forms. In some of these threads siding is only one of the topics.

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/41169/afv/topic/afpgj/2/Default.aspx#57902

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/60020/afv/topic/afpgj/2/Default.aspx#43397

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/59500/afv/topic/afpgj/3/Default.aspx#43098

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/56941/afv/topic/afpgj/1/Default.aspx#41199

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/53265/afv/topic/afpgj/2/Default.aspx#38306

I've included this shot of prefinished Hardiboard siding going up directly over TF System vertical ICF.  It should be noted that because the continuous vertical PVC strip is embedded 5/8" below the surface of the EPS, if you screw the HB to the strips (as recommended by TF System), you will compress the foam in an attempt to countersink the screw heads.  I used #8 1-3/4"  Marker Dart CWL-Drill fiber cement screws.  To avoid compressing the foam as the screws countersink themselves, I ended up pre-countersinking each screw with a masonry bit.  This slowed me down a lot.   Next time, I would cut away the EPS over the PVC and attach a wood furring strip over the PVC stud and nail the siding into the wood.  Either that or simply nail the siding into the PVC with ring-grooved nails as others have done.

Clark-- food for thought/consideration. Just reviewed your picture. You will want to put foam over the wood gable - this is more or less critical in my opinion. as you will have very poor thermal performance there. Also, over porch that area of the attic should be vented and "outside". In other words you need a false wall running up with your TF to keep that portion of your attic outside. I am assuming you are foaming your attic (overhead). Regards.

Actually, the attic is vented, therefore no insulation is required on the gables. Thanks.

Clark,

You may want to reconsider. I am concerned that you will be one of the very few ICF guys out there that is not elated with energy costs or lack thereof. At any rate, I hope you at least foam and not BAT. If not (from an energy view) you will have a screen door on a submarine. Regards.

The ceiling is sprayed-on closed cell polyurethane. Measured 2 BTU/sf/HDD energy efficiency.

Posted By BrucePolycrete on 27 Jun 2010 02:11 PM
An inexperiened ICF installer may have a tough time with TF, as they can be tricky -- particularly in windy locations, so make sure he has been properly trained or (as I mentioned to you in another post) please hire a professsional installer. There are good installers in Montauk area.

I know this is an old thread but it came up on a google search so:

My 2 cents, TF is a great system for an inexperienced installer. I did it with no formal construction background.

Posted By onesojourner on 06 Mar 2013 12:10 PM

Posted By BrucePolycrete on 27 Jun 2010 02:11 PM
An inexperiened ICF installer may have a tough time with TF, as they can be tricky -- particularly in windy locations, so make sure he has been properly trained or (as I mentioned to you in another post) please hire a professsional installer. There are good installers in Montauk area.

I know this is an old thread but it came up on a google search so:

My 2 cents, TF is a great system for an inexperienced installer. I did it with no formal construction background.

I agree.  Did you take the two day class offered by the manufacturer?

This sounds like a great product for a passive solar house we are currently designing. It appears to actually allow the concrete core to be better used for thermal mass than block ICF systems given that nearly all of the insulation is on the external side. It also appears to have less issues in getting straight walls than block ICF systems. For those who have actually used this system (and not are promoting their own product), how does it compare to other products in terms of cost and construction labor?  How was the training?

Submitted two customized buildings to TF for takeoffs, so we shall get definitive info from the source. If the cost is acceptable and we go with it for these projects, we will post more info.

So far, I have been impressed with the customer service, pricing, and many design/build advantages of this TFSystem.com product. I will post our experience using it for a remote, two building, with passive solar & hydronic radiant floor heating, residential project. However, you will have to wait until Spring 2014 to see it given the location remoteness and the need to first get the required infra structure accomplished (access, well, hydroelectric power, irrigation/fire suppression, and septic) this season. In the mean time, here’s a good video of this product:

TFSystems

The sales video is pretty much on the mark. Even as an inexperienced ICF builder, I had no problem using TF System. It was actually fun to install. A couple nits, though: The video shows a panel being raised up to retrieve a tool or to inspect the reinforcing. I found that it's not all that easy to slide a foam panel up. It tends to bind on the adjacent panels. Also, maintaining the 12" o.c. spacing of the "studs" around windows and doors increases the number of studs needed and the increased ripping and grooving of panels produces more waste. Although the studs are continuous vertically, they are embedded about 5/8" below the surface of the foam. Screwing finishing materials, e.g., Hardie Board siding, directly to the ICF will compress the foam, distorting the siding noticeably. Power nailing with ring shank nails avoids this problem, but won't have the holding strength of screws. Although a bit more expensive than most block ICF, in all other aspects, I found their system really nice to use.

Had no problems with Hardieplank (4" reveal) over ARXX forms. The exposed web provides an excellent hardpoint so the lines are straight and even. Make sure you really want the 4" reveal, however. It was quite tedious. You can calculate how many more planks need to be cut, aligned and fastened with a 4" reveal than with the next largest reveal (5"). You may want it for closeup viewing, but with any distance at all the 4" reveal starts to blend together. ARXX block corners are a bit irritating due to having only one anchor point.

Yes, thanks for the cautions/tips regarding the fastener issue Clark. We will certainly ask them about that when we get their training in a couple weeks. We won't be installing HardiePlank...likely 10" cedar log siding...but the issue will be the same. Seems like if we were to use self tapping screws with the appropriate dimension of unthreaded shank below the head (i.e., 5/8" + siding fastener thickness), this might address this issue...as there wouldn't be anything to grab and compress the foam...and perhaps with less risk of stripping the studs in the process too.

It's not the threads grabbing and compressing the foam, but pulling the siding in too tight that compresses the foam. Clapboard siding doesn't lay flat, but is at an angle, so there is a pressure point at the top of each plank. Over tightening the screws will pull the top into the foam right where the screw is. If the material lays flat on the foam, and is thick enough, it would strip the stud before it compressed the foam.

I am using battens on my outside walls to create a drainage plane behind the siding. That way, moisture that gets behind the siding can dry rather than staying trapped.

Has anyone used TF in windy conditions?