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Does anyone know a builder who can build this for me?

user-1146678 | Posted in Green Building Techniques on

Since this is a green building forum I thought I post here

See pic below.
the bricks used are ‘thermo blocks’ however I can live with regular cinder block too.
basically we want 5-6″ slab on each floor and a concrete pillar structure. unlike the example pic below, 2 floors is enough

Does anyone know a builder? Area: MD-VA-DC

Thanks a million!

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  1. GBA Editor
    Martin Holladay | | #1

    Don J.,
    The building looks like a thermal disaster. Are those cantilevered slabs? If so, they will leak heat like the fins on a radiator.

    What is it about this style of construction that attracts you?

  2. user-1146678 | | #2

    Hi Martin
    to prevent thermal disasters the above building is usually covered in foam board insulation and then stucco over. I observed most public buildings around our area are actually built in a similar fashion, except cinder block instead and I don't think they pour concrete slab over each floor perhaps...
    Obviously a roof is going to be installed too, with foam boards on top of the upper most slab
    To answer your second question, comfort and relatively low cost especially in the long term

    I believe ICF builders are coming close to the above aren't they?

  3. Expert Member
    Dana Dorsett | | #3

    Insulating "structural tile" terra cotta blocks were popular in the southwestern US from about 1900-1940, since they were as cheap or cheaper than cinder block and you could finish them easily with plaster on the inside, stucco on the outside, or sometimes with ornate glazed terra cotta tile siding. IIRC it's still a common-enough building material in parts of Latin America, also in parts of Spain & France too as a cheaper alternative to CMU. They're slightly higher-R than standard CMU, but nowhere near code-min R for MD/VA on their own. The ones in the pictures have a greater number of cores than the early 20th century versions which would increase thermal performance, but I'd be surprised if you got even R5 performance out of them in a single wythe (probably more like R3-4, compared to R2-ish for a standard core CMU.)

    A concrete post & beam type structure with insulating terra cotta cladding won't have the radiator fin effects Martin mentioned, but it's still probably not a great material for cladding either. Unlike the dry climate of the southwest or Mexican deserts, in MD/VA you're likely to run into freeze/thaw spalling issues using terra cotta in wall structures. The stuff is very porous and softer than CMU or hard brick. Terra cotta can hold a lot of water, but it's not very resistant to the internal pressures created by water crystalizing in the material- above some minimal moisture level the surfaces will start to crumble as it freezes. It's possible that some manufacturers have improved the process, maybe with higher-temp firing or different glazes and clay component types etc to mitigate those issues. I'd be a bit surprised if it works long term in your climate, but maybe-googling around for info on it there are manufacturers of terra-cotta siding panels for commercial buildings in cooler-wetter Germany. . You'd still need to figure out how to get to code or better on R-values though.

  4. GBA Editor
    Martin Holladay | | #4

    Dana and Don,
    The problem is the cantilevered balcony slabs. You can't really wrap a balcony slab in foam, and no one ever does.

  5. Expert Member
    Dana Dorsett | | #5

    But Martin, he wasn't talking about building balcony slabs, only building structural concrete:

    " ...basically we want 5-6" slab on each floor and a concrete pillar structure. "

    Without the cantilevered slab the structural goods can all stay inside the terra-cotta & foam skin.

    The balconies in picture are sort of a red-herring, not how he intends to build.

    I'm still don't get what the attraction of terra-cotta block construction is- the thermal performance difference between terra cotta block and a poured concrete or CMU wall is less than an inch of EPS, and I doubt it'll be substantially cheaper in a MD/VA location.

  6. user-659915 | | #6

    The blocks shown in the photo are a curtain wall infill, not a cladding. As such they will make no contribution to protecting against the severe thermal bridge provided by the concrete frame. The foam thickness must be calculated to provide all the required wall insulation value, i.e not less than about 4" in most parts of the US. The block contribution is small enough be ignored, although I suppose you could boost it a little in the infill areas by using AAC instead of the tile. The technique is familiar all around the Mediterranean though in those mild climates the insulating foam is usually omitted.

    That said any commercial contractor could build this for you, poured in place slab and column construction is pretty common in commercial construction. Le Corbusier tried to introduce the technique to residential construction with his 1931 Villa Savoie but fortunately it never really caught on in the colder climates. BTW, it will not be a cheap build.

  7. user-1146678 | | #7

    For some reason this forum always drifts into discussions about insulation. ;)
    First off I can assure you you are concerned about the wrong thing. When you live in one of these homes you know its value as well as its shortcomings, as with any home and structure. Insulation, freezing, etc. are definitely no issues.

    I looked up the R value for the brick alone is 5.5 without foam board (it's quite wide). I have seen the foam can be sandwiched between two bricks which is another common practice. I beg to differ regarding cost and cold climate issues. I have seen this technique being used all around the world in all different climates. And by adding a 2" foam you would easily reach R10-15 that's plenty for walls anywhere. The balcony will freeze of course but that doesn't affect much the interior, I can tell from experience. Obviously you need good balcony doors. Never seen/heard any issues whatsoever with freezing even when the house has no roof or isn't painted. Actually even if no stucco is applied. A friend of mine kept the upper slab exposed for almost 20 years. The freeze cycles did take about half an inch off but that's pretty much all that happened after almost two decades.
    Btw, another common brick alternative is aerated concrete blocks,
    especially for interior walls I've seen this being used a lot lately

    Brick does absorb a lot of moisture but also dries very fast. This isn't solid 1800s brick....

    I have seen some homes in NYC in construction, so it is being done but the question is whether someone specializes in this kind of construction for residential properties.

  8. wjrobinson | | #8

    ICF builder.

    That's it as to your quest and as to what's readily available and even with ICF, you are down to 1% of what and who and why and how and... Etc...

    No? OK try this..... Stop in on 100 building sites and note how many are building what you desire....

    0... Is my bet.

    Good luck.

  9. homedesign | | #9

    I believe the blocks pictured look a lot like "Ziegel" blocks.
    I may be wrong... but I believe they are structural (load bearing) and they also have "decent" R-value.
    I believe they are being used in Passivhaus projects in Germany, Switzerland and the UK.

  10. GBA Editor
    Martin Holladay | | #10

    Don J.,
    You wrote, "The balcony will freeze of course but that doesn't affect much the interior, I can tell from experience." Well, you are right that millions of people live in high-rise buildings with cantilevered balcony slabs, and most of them are comfortable. The reason they are comfortable is that the buildings have heating systems that make up for the substantial heat loss through the projecting concrete slabs. Somebody has to pay that heating bill.

    If the building had a better thermal envelope, without the protruding balcony slabs, it would be a wiser design.

  11. user-1146678 | | #11

    yes I bet these bricks are also used at almost 100% of all Swiss building sites, that should be a positive sign this type of construction works well in really cold climates.
    Now the thing about the thermal envelope with balconies may be correct but I wouldn't say it's dramatic. Also each slab may be insulated using XPS encapsulated inside the slab.
    What we plan to do is put XPS on top of the slap and add a thin layer of concrete over it. This is usually done to level the floor nicely so you can install ceramic tile.

    AJ's comment makes sense too but only if you have restricted US vision. If you visit 100 random cities around the world, it's actually our stick frame construction you won't find a lot elsewhere. I have seen stick frame only in Canada, and newer UK and IRL construction. And yes, it's only done by major corporations in UK who want low cost. I haven't met anyone in the UK praising stick frame homes. Did you know in IRL the stick frame homes have vents in every room's exterior wall so the drywall doesn't rot/grow mold!? On a windy day you feel like you're outdoors...Talk about energy efficiency in the long-term!

    Regarding cost, well I have seen the concrete construction shown in the picture also in Brazilian slumps I visited. That's when a bell rang in my head. If they can afford it, there is absolutely no reason we can't do it in the US.

    I haven't seen ICF in person I would like to see how it's done and the finished product. I was thinking about getting the exterior walls done as ICF and using the aerated concrete blocks for interior walls, then stucco over everything.

    Don't you like balconies? I love them. Sunset, a cup of espresso, people watch, fresh air, keep the door open at night. Fantastic feature to have in a home. To offset your energy bill, hang your clothes outside ;)

  12. Expert Member
    Dana Dorsett | | #12

    If these goods work well in Switzerland they're going to work just fine in MD/VA.

    It's good to know that the block actually performs at R5+ rather than R3-4ish levels I was guesstimating. I'm a bit less sanguine about the use of 2" XPS to bring it up to code-min though. Unlike the XPS use in Europe, which is blown with CO2, all XPS currently manufactured in the US has a fairly hefty greenhouse-gas footprint due to the amount of HFC134a used in the blowing agent mix. (It's global warming potential is on the order of 1000x CO2 or depending on the exact mix.) Using either EPS or polyiso instead would have less than 1% of the greenhouse gas hit of XPS from blowing agents. At 2lb density (aka "Type-IX) EPS has the same or better compressive strength as most XPS ( if only 85-90% of the R-value at any given thickness.) Most ICF is made with 1.5lbs density EPS, which is still pretty good stuff, but noticeably softer.

    In walls there are some advantages to using polyisocyanurate (PIR) instead of polystrene (XPS or EPS). With PIR get higher R/inch, and unlike polystyrene it will not melt even while burning, and it has a higher kindling temp than polystyrene too. Both PIR and EPS are usually somewhat less expensive than XPS per unit-R

    The notion that use in Switzerland is "...a positive sign this type of construction works well in really cold climates." is a bit off the mark. Most of Switzerland is fairly temperate even compared to southern New England. The population centers of Zurich & Berne are SUBSTANTIALLY warmer in winter than my US climate zone 5 location, if somewhat cooler than MD. Even Andermatt has a warmer winter, than Springfield MA, or Albany NY, which aren't exactly characterized as "...really cold...", in north American terms, merely a " kind of cold".

    There is also something amiss in the statement, " adding a 2" foam you would easily reach R10-15 that's plenty for walls anywhere."

    R15 continuous-insulation would make code-min in MA, but not R10 (which would also not meet code-min in MD.) R15 is sufficient for meeting code in MD or VA, but not exactly a high-R assembly. "Plenty" depends a bit on what your energy use goals are, and the actual "where" in the term "anywhere".

    R15 would NOT meet IRC2012 code minimum for US climate zones 6 or higher. (Say, northern New England, or southern Wisconsin.) It would squeak by code min in zone 6 only in mass-walls, with the preponderance of the insulation on the exterior, but would still be sub-code in zone 7, even in mass-walls. See:

    While building to IRC 2012 code min isn't exactly an energy-hog, there is usually a longer term rationale (and a comfort rationale in the shorter term) to going higher R that that. A rough guide on the long term financial break-point discussion can be found in Table 2, p10 of this document:

    MD/VA is US climate zone 4, where they're suggesting R25 walls can be rational, depending on construction & energy costs, which is about where you'd be with the R5.5 block (unbroken by thermally bridging concrete) and 3" of continuous rigid polyisocyanurate, or 5" of EPS.

  13. user-659915 | | #13

    "I have seen the concrete construction shown in the picture also in Brazilian slumps (sic) I visited"

    Hmm. 'If it's good enough for Brazilian slums it's good enough for me' is not exactly a resounding recommendation. IMHO.

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