A friend installed Hardiboard siding on the exterior of an ICF garage and trimed the corners with a PVC type material.  When the temperatures dropped he saw gaps of up to 1/4".  He thinks the PVC material shrunk.  He said he didn't see this happen with stick construction.  I'm thinking the ICF wall doesn't expand or contract with the cladding like a stick wall with OSB exterior.   He's awaiting inputs from his supplier.   Thoughts?  Dave

Don't blame the ICF wall for being stable. I didn't think Hardiboard or PVC was supposed to react that much to changes in temp and humidity.

PVC can expand/contract quite a bit. That's why vinyl siding has fairly long slots for the screws, why the screws shouldn't be run down tight, and why you overlap adjoining pieces instead of butting them. But 1/4" from trim pieces sounds like a lot even then. I don't think the Hardi will move much at all, otherwise you wouldn't be nailing/screwing it tight. Some plastics will shrink from sunlight or time also. I had plastic floor panels for a shed shrink a 1/2" in 12' from being in the sun for only a few hours. Since these are corner pieces what's the chance they backed off of the ICF for whatever reason? And it just might be bad or exceedingly economically priced material.

Very well put -- don't blame the ICF for being stable. Regards.

I considered using PVC corner boards with my Hardiboard siding over ICF, but my supplier talked me out of it due to the dimensional instability of PVC. I used MDF and haven't had any problems with excessive expansion and contraction.

MDF outside?

Posted By Jelly on 27 Apr 2010 10:20 PM
MDF outside?

I thought exactly the same thing. I think he probably meant composite wood, like Truwood. That's what I used.

Posted By dmaceld on 28 Apr 2010 01:01 AM

Posted By Jelly on 27 Apr 2010 10:20 PM
MDF outside?

I thought exactly the same thing. I think he probably meant composite wood, like Truwood. That's what I used.

It's a product called MiraTec. I was under the impression MiraTec was an exterior grade MDF. My mistake.

MiraTec is a hardboard product.
What shrunk the siding or the PVC trim?
If it was the trim it was probably installation error.
Fiber cement siding was supposed to be a stable product but is clearly shrinking and cracking on installations all over the US, in fact doing a warranty job in a couple weeks where the siding failed. It lasted about 4 years and gapped all over the place, now 20 square need to come down and get replaced.

And the injection of icf being so stable that this only occurs on stick is complete bollocks.

Greentree, ICF is the top bollocks/dog's bollocks -- when it comes to stable. I'm sure you know what that means or you wouldn't use the term. This thread started with someone trying to determine if ICF had something to do with a problem. The implication that this might occur with ICF and not with stick is what is bollocks. ICF is rock and stick is sand. Regards.

Yea, and concrete never cracks. Regards.

Yes. It's all temporary in the big picture. In the absense of fire and termites -- it's the relative scale I'm referring to -- a few years for wood and a thousand for reinforced concrete. Regards.

Posted By TexasICF on 30 Apr 2010 09:11 AM
a thousand for reinforced concrete. Regards.

Not necessarily. It's my understanding concrete is good for about 100 yrs + is all. 50 yrs curing and getting stronger and 50 yrs going in the reverse. There are some schools in Idaho where the concrete basement foundation wall wasn't much more than sand after something like 50 yrs. Falling Water, the all concrete mountain summer house Frank Lloyd Wright built for the Kaufman family in Pittsburgh started to come apart after about 50 yrs. The Kaufman children donated the house and land to the state for a wildlife conservatory rather than face the cost of repairs. There's concern about old concrete dams on rivers in the NW because of deterioration, and they go back less than 100 yrs.

That concrete you speek of was not protected from all of mother nature's elements.
Now icf's are. I know you're a fan of icf's ,what you're take on protected concrete?

Never really thought of it terms of protected vs. unprotected. It's my understanding the deterioration with time is a chemical reaction that takes place through the entire mass of concrete. The deterioration of unprotected concrete would only be "skin deep" I think. One example that demonstrates the continuing chemical reaction is the fact that the cooling water pipes that were embedded in Grand Coulee dam weren't taken out of service until sometime in the 1960s. Dam construction started in 1933.

What would be really interesting would be to see some data that correlates the stability of concrete over 100 yrs vs. the slump, water/cement/aggregate ratio, additives, etc. Although there is no way to know now, I think it's possible an ICF wall might crumble after about 100, or 150, or 200 yrs. But in any case, I'm absolutely sure my ICF walls won't crumble in my lifetime! After that, I really don't care what happens!

Good thing those Egyptians didn't construct the Pyramids out of concrete! ;)

Update. The supplier is coming to assess the situation and has offered to upgrade to a denser material. Also, correction...the gap was a total of 5/8". Or 5/16" for each piece of trim on about 10' long.

The thread did take a very interesting sidetrack regading the lifespan of concrete, which I look forward to learning more about. In the late nineties, I did drive on the 1930's vintage concrete autobahn in the former East Germany which appeared to in structurally sound condition. Except for the rough construction joints, it was still performing well 70+ years later.

Just finished salvaging much of the 1920 house on our farm and exposed the original 10-12" thick stem walls constructed of concrete which used a bit of local limestone and gravel for aggregate and was reinforced with strands of barbed wire. A couple of sledge hammer blows knocked them apart which will make it easier to remove, but at least they supported the walls for 90 years. The Pyramids probably wouldn't have lasted long with this mortar mix.

Concrete does not get harder for 50 years and then begin to deteriorate. Throughout it's life it continues to cure, which means gain compressive strength. It is substantially cured in 28 days, but try drilling into 5 year old concrete versus 2 month old concrete, and you will understand that it gets significantly harder.
As concrete cures, the chemical bonds do not deteriorate. When one sees crumbling concrete there are quite a few possibilities.
1) the concrete was loaded beyond what it was designed for.
2) Poor quality materials and/or installation (this could take ages to discuss)
3) Non air-entrained concrete was exposed to freeze/thaw cycles.
Properly done, concrete will last hundreds of years, and perhaps thousands.
Jake Vierzen
R-Value Concrete Structures

Thank you rvalue - some of this discussion... well is a little painful....

The oldest known concrete shell, the Pantheon in Rome, was completed about AD 125, and is still standing. It has a massive concrete dome 43m in diameter, with an oculus at its centre. A monolithic structure, it appears to have been sculpted in place by applying thin layers on top of each other in decreasing diameter. Massively thick at the bottom and thinning (with aerated volcanic pumice as part of the concrete mix) at the top, the Pantheon is a remarkable feat of engineering.

The Panthon is quite an accoplishment but i doubt the Romans knew more about about concrete design mix 2000 years ago than we do today. Regards.