Interesting new insulated block from Eco-Panels
Thought people might be interested this new (not on market yet) post-tension, CMU block …
excerpt:
What is the EPIC BLOCK?
A traditional CMU wall is much stronger than it needs to be for most projects and it lacks any real semblance of energy efficiency or simple assembly. Combining the benefits of durable and fire resistant concrete with the best insulation on the market, the easily stackable EPIC Block consists of a dense molded insulating foam core which, like the web of an I-Beam, bonds together two load bearing durable side “skin” materials. The patented profiled nature of the molded foam core allows for a strong and air-tight sealing of multiple blocks even without the use of adhesives or a compression fitting.
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It looks interesting. I had to go pretty deep on the website to find it, but they claim it is structurally superior to CMU's. I think that would be a big selling point. Around here CMU is mostly used for small projects where pouring concrete wouldn't be feasible, like an addition on the back of a house with a land-locked back yard. If it's faster than CMU and doesn't require a skilled trade I could see that making up for the blocks being somewhat more expensive.
I thought it was an interesting use case that the blocks could come with wood on the interior for hanging drywall or cabinets.
Below ground the outside would have to have a fluid applied coating to keep out water and bugs.
One thing is that it looks like it can only be used in preset sizes, the blocks won't fit together if they're cut. I could see blocks coming in quarter-block increments, probably about 2" increments. I'm not sure that's precise enough.
I also didn't see how openings for windows and doors are done.
When I worked at FoamTech (long time ago) we also had a post-tension, CMU block that we would inject with polyurethane foam called the Integra Wall (Old Castle parent - no longer available)...
It wasn't completely thermally broken, but the foam was applied in the field rather than the factory (kind of like the concrete is for the "Perfect Wall").
https://www.integrawall.com/introduction.htm
re: "the wood on the interior" it's actual shown on both sides like a true SIPs panel, but that reminded me of the Gablok product in Europe
https://www.gablok.com/
I'm very skeptical. The website mentions I-beam strengths for an individual block but the strength of a wall assembly would depend on the bonds between the skins on the individual blocks. The blocks aren't bonded together at all at the skins if I understand correctly. So much for your I-beam. Even if they were bonded together, concrete would make an exceedingly poor skin material in tension.
From the company I used to work for that had a similar "post-tension" block system with poured in place polyurethane foam ...
From "Energy Design Update" newsletter (by JD "Ned" Nisson)
http://www.foam-tech.com/products/integra_post.htm
excerpt:
"Post-tensioning should not be confused with conventional reinforced concrete, which uses reinforcement bar-embedded in grout to provide strength. Post-tensioning employs a completely different engineering principle. The purpose of the tensioning bars is to compress the blocks. Once compressed, the inner and outer block faces carry the full load."
The Epic blocks use threaded rod where you would normally put rebar, and it also provides the tension.
Looking at the Home Depot website, 1/2" rebar is about $0.70 per foot, and 1/2" all-thread is about $3.00 per foot. It looks like they want rods on 8" centers, so you'd need 1.5 feet of rod per square foot of wall. So that would be $4.50 per square foot just for the rods. That seems like a lot to me.
Actually a 10' all-thread rod is $16, so $1.60 per foot. So $2.40 per square foot.
Note that there are various grades of threaded rod. The usual hardware store stuff is grade 2, and not particularly great for tensile strength. You can get grade 5 threaded rod which is very much better, and the minimum I would use for something like this.
BTW, I like that the blocks don't seem to have the usual web of masonry, they look like a concrete version of a SIP. Lots less thermal bridging that way. I'm very concerned that they closely resemble Lego bricks though, which means my 7 year old daughter is going to want to play with them ;-)
Bill
Forget 7 year old, I want to stack those. Lego for adults!
At least you don't have to worry about stepping on them!
They do look like they'd be really appealing for DIY types. Pour a slab and some footers, throw up walls and some trusses for the roof and you'd have a pretty good building pretty quick. They'd look particularly appealing for off-grid sites where things can't be trucked in, you could carry in enough for a house on your back if you had to.
If they intend to market this nationwide they'll certainly be doing some kind of seismic testing of full scale wall sections, otherwise it will be useless in seismic zones C and D. The strength of the block itself matters little if they wall assembly can't be tied together to properly resist in plane shear, which is not the only structural issue, but the key one for avoiding dangerous non-ductile failures.
I got my degrees in architecture and structural engineering. And my first job out of university was in an engineering office. I can hear my boss's voice now. He wouldn't go near these without comprehensive physical test results.
But if you're building in zones A or B and you provide good uplift for your roof connections, blocks like this might be a good solution. So they're probably a best fit for Florida and the Gulf coast.
I cannot see where this would be cost competitive for anywhere within 50 miles of a concrete plant. Mixers can be rented, and concrete can be pumped.
Gus-
Many in the industry are trying to find alternatives to concrete (climate) that you don't need to go to a sub-contractor for & can be DIY
This is why there seems to be (at least I am noticing) renewed interest in Permanent Wood Foundations, as well as, "slabless" slabs (plywood over foam).
I understand this, but it comes down to money. There is still a fair bit of concrete in the product.
Getting too deep for nesting.
Re Threaded rod.
You can get much lower cost from wholesale suppliers significantly cheaper than a box store.
There are also nuts you can put on rebar, don't know if that would work in this application but would certainly be cheaper and easier as you won't have to deal with splicing.
Today I learned that you can get rebar with threaded ends. I'm not sure what it's for, I think it's for when you need a long continuous piece of rebar.
I think that would be perfect for these blocks. Sink a j-bolt into the footer, screw a piece of rebar into it, build your wall and then put the sill plate on and put bolts on the top to tension the rebar and hold it all together.
The wall seems to have a lot of steel in it, more than I would think it would need. I think it's driven by the need to have two rods in each block so they tension evenly. I don't see why the blocks can't be bigger, if they were 32" the bar would be on 16" centers. I'd make the blocks as big as they can be and still practical for one person to install. Everything about the construction goes faster if the blocks are bigger. Which begs the question, would it work better if the blocks were, say, 8'x8' sections?
The sill plate is being asked to do a lot structurally to tension the wall and hold it together, I wonder if a piece of treated 2x8 is up to the task or whether it needs to be something more robust. The sill is going to have a bunch of holes all in a straight line down the middle of the board, I could see it splitting in two when all those nuts are tightened.
I like this idea but it seems like it still needs some fleshing out.
Hi DC!
In speaking to eco-panels, I was told you don’t need a threaded rod for every chase – that the assembly was not tested in the way you described above w/your "$4.50 per square foot just for the rods" estimate. The frequency of the threaded rods - depending on a number of factors - will be determined by a structural engineer.
Their expectation in an apples to apples comparison of costs (after having to potentially cover the EPS on both sides) is to come in at par with an ICF (Insulated Concrete Form) construction when fully assembled.
If people had read their website a little closer, you should see that after essentially seeding the market, their longer term growth strategy is to actually partner with concrete companies across the country so production would always be relatively local to the build location.
A little bit of googling tells me you can get SIP's meant for below-ground use as basement walls. I have no idea how good they are, I know there's a history in the SIP business of over-promising and under-delivering.
But it seems to me that if what you want is a pre-assembled, insulated basement wall assembly, you're much better off starting with a full-height panel rather than an 8" block.