Fiber Cement on ICF
Last Post 13 Jun 2009 06:31 PM by Alton. 16 Replies.
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Boontucky-girlUser is Offline
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28 May 2009 10:35 AM
We are going to be installing certainteed fiber cement on ICF using screws.
The debate now is screw every 8" onto each tie, or screw 16" o.c. every other tie?

Certainteed says see block manufacturer recommendations, block mfg. says follow siding instructions. I'm at a loss here, and I've contacted certainteed but no one ever gets back to me.

Any help?
icfcontractorUser is Offline
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28 May 2009 11:32 AM
Boontucky,

Certainteed has scant info about proper installation of their product. If you go to the James-Hardie site you will find that they have a way more comprehensive site for installation of their product. I have not personally installed the Certainteed product but know other contractors that install it to the Hardie specs of 16" OC.

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JakeGUser is Offline
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28 May 2009 12:18 PM

Boontucky,

I have installed the James-Hardie at 16" OC with ICFs.

It is up to Certainteed to spec how to mount their product, NOT the substrate manufacturer.  If you have already purchased your Certainteed product, I would be a little more forceful and request info.  Start at your supplier and work your way up.  When I've purchased product from my local hardware store and had questions they couldn't answer, they have called the manufacturer right then and there while I wait for an answer.

If you haven't purchased the board already, it might be a good time to price out other similar products if you are not getting the answers you are looking for.  Don't take chances and pay for it later.

Good luck.

 

dmaceldUser is Offline
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28 May 2009 08:44 PM
A good resource anytime questions like this come up is the ICC-Safe web site, http://www.icc-es.org, to see if the mfr has an ESR report available. For Certainteed lap siding download this PDF: http://www.icc-es.org/reports/pdf_files/ICC-ES/ESR-1668.pdf.

Dig down in the report and you'll find the nailing and screwing schedule for various siding widths for face nailing and blind nailing, and the wind loads that nailing or screwing schedule is rated for. The only other bit of info you'll need is what design wind load is required by the applicable building code for your locale. Your local building officials should have that number.

Find the schedule for the siding you plan to use for the wind load you need to fasten for, and do at least that or more.

From what you've said you'll find more info in that report than those you've asked have been able to give you. Sadly, people in the business of selling products often don't know what the mfr actually recommends about installing or using it. And people in the trade often don't know. They just do what they've always done to get the job done, collect the check, and move on.

Once you've studied that report and if you have any questions for which you don't find the exact answer, come back and we'll see what more help we can offer.

For my house I used Hardiplank. Because the ESR didn't address fastening into ICF webs I took the closest nailing schedule I could find and went better, i.e. a nail in every web.

One example of lack of knowledge I just encountered. The sales manager at the local distributor, a national green color landscape company, for Hunter lawn sprinkler products didn't know Hunter recommends a 100 mesh filter for the MP Rotator sprinkler heads. I had to show it to him in the Hunter installation manual. "Everybody just uses 32 mesh," he said.

Even a retired engineer can build a house successfully w/ GBT help!
ClarkUser is Offline
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31 May 2009 12:26 PM
I just completed installing 18 squares of 7.25” fiber cement (Hardiplank) siding over ICF. The ICF (TF system) has a continuous vertical 2” wide PVC strip, 12” on center, embedded 5/8” below the surface of the EPS for attaching siding, drywall, etc. The manufacture recommends using screws to attach this siding. James Hardie does not specifically address installation over ICF. My experiments with ring shank nails showed inadequate holding strength. I chose to use 1-5/8” Marker Dart fiber cement, coated screws which are self-countersinking. This screw accepts either a #2 Philips or #2 square bit to drive the screw. I attached the siding at each PVC “stud.” The screws would not self countersink without compressing the foam about 1/8”, deforming the siding in the process, and making the siding appear wavy. To prevent this effect, I had to pre-countersink each screw using a carbide tipped drill bit and take care not to overdrive each screw.

Before siding, I used a rasp to knock down high spots on the ICF wall. TF system uses a dense 2 lbs/cu ft EPS for their forms which is a lot of work to rasp, so shimming was also necessary to compensate for any remaining variations in the flatness of the ICF wall. Fiber cement siding is not very stiff and will telegraphs the contours of the underlying wall surface. If you want a nice looking job in the end, you have to take the time to flatten the wall and prevent screw compression of the foam.
jdebreeUser is Offline
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31 May 2009 01:45 PM
Thanks for the comprehensive info. I'm thinking about TF system, and I'll definitely be going fiber-cement siding. Sounds rather labor intensive to do it right.
AltonUser is Offline
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31 May 2009 02:05 PM
I wonder if installing furring strips over the ICF would have simplified the HardiePlank installation.  At least it would create a drain plane.  I believe the amount of shimming and sanding would have been reduced and regular screws could have been used to attach the HardiePlank.  What am I missing here?
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ClarkUser is Offline
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31 May 2009 02:29 PM
When I took the ICF construction course offered by TF System, the subject of siding over ICF was brought up by a student. An experienced contractor in the audience recommended using furring strips screwed to the ICF and nailing the siding to the furring strips. I assumed his point was that this method would provide better ventilation of the siding to preserve the paint/stain finish. That may have been the case, however, I now believe it could also make installing fiber cement siding over ICF easier and give superior results. Of course, one would have to account for the extra thickness of the exterior cladded when installing the windows and doors. Has anyone used this method successfully?
icfblocksUser is Offline
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31 May 2009 09:37 PM
Not being completely with the TF system I don't understand the "High spots".  Having done quite a few ICF jobs using both assembled block and panel block systems They typically don't end up with any "high spots" or other unevenness.  If some occur certainly they need to be rasped flush. 
The system I am currently installing has a built in "drain screen".  I have seen Hardy plank installed over it with no special care taken.  I certainly would not want to have to furr out the exterior to add a siding product to finish an ICF job. 
Thanks,<br>Tom<br>www.advbuildingtech.com
jamesmacdonald1User is Offline
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01 Jun 2009 08:30 AM
I agree with Clark. Although it may not be necessary, having the additional airspace/drainage plane is never a bad idea and worth the effort. I certainly would do it on my own home and therefore recommend it to others.
BruceUser is Offline
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01 Jun 2009 12:00 PM
Posted By icfblocks on 05/31/2009 9:37 PM
Not being completely with the TF system I don't understand the "High spots".  Having done quite a few ICF jobs using both assembled block and panel block systems They typically don't end up with any "high spots" or other unevenness.  If some occur certainly they need to be rasped flush. 
The system I am currently installing has a built in "drain screen".  I have seen Hardy plank installed over it with no special care taken.  I certainly would not want to have to furr out the exterior to add a siding product to finish an ICF job. 

What system are you currently using that has a built in "drain screen"?

Thanks,
Bruce
icfblocksUser is Offline
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02 Jun 2009 07:33 PM
Currently using IntegraSpec. 
Thanks,<br>Tom<br>www.advbuildingtech.com
jonrUser is Offline
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03 Jun 2009 09:16 PM
If you were going to use furring strips, might as well throw a layer of Tyvek attic wrap on first (for the insulating benefit of a radiant barrier next to an air space).

I wouldn't use furring strips if there were termites though.

AltonUser is Offline
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04 Jun 2009 08:20 AM

Synthetic furring strips are available - no food for termites.

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ClarkUser is Offline
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07 Jun 2009 11:20 AM
With TF System (or any type of ICF block for that matter) it's difficult to get a perfectly flat wall.  TF System uses vertical EPS panels 1' wide tied together with PVC I-beams.  This makes for walls which are quite straight vertically, but allows some variation in the horizontal direction, mostly at mid-wall.  Also, if the slump of the concrete is too high, or if the concrete is over consolidated, some bowing of the panel can occur between the ties.  Rasping out these irregularities to get perfectly flat surface is hard work due to the rather high density of the EPS used by TF.  A lesson learned is to pay more attention to the horizontal bracing of the TF panels at mid-wall.  The manufacturer's installation guidelines don't call for mid-wall horizontal bracing, but, in the future, I would include it.  I, too, prefer not to use furring.
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13 Jun 2009 02:03 PM
Alton, where would I find info on synthetic furring strips? maker, product name? thanks so much!
AltonUser is Offline
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13 Jun 2009 06:31 PM

Chris37,

The synthetic furring strips that I had in mind are really designed for roofs but I think they should work also for ICF walls to make a rain screen if desired.  You could always ask the company.  Here is the web site for the product that I have seen:  http://www.battensplus.com/

The price for these could be compared with other synthetic products such as Trex:  http://www.trex.com/  and other composites.

Or compare with http://www.timbersilwood.com/ for real wood with a warranty for 40 years.

Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979


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