Air-crete Building

“What is Air-crete? Air-crete is a lightweight cementitious material that contains stable air cells uniformly distributed throughout the mixture. It is a concrete which utilizes a stable air cell rather than traditional aggregate. It is also called cellular concrete, foam concrete, light weight concrete, aerated concrete etc. Typical concrete has a density of 140 lb/cu.ft. Air-crete densities range down to 20 lb./cu. ft.

What is the correct water to cement ratio for the cement water slurry?
Typically, a (1 to 2) water to cement ratio slurry is used as a base mixture for Air-crete. The water cement ratio may be varied according to specific project requirements.

Does Air-crete contain either fine or course aggregate?
Air-crete may contain sand but not coarse aggregates. Air-crete is designed to create a product with a low density and a relatively lower compressive strength when compared to plain concrete. The typical density range of Air-crete is 20 – 60 lbs/cu.ft. which develops a corresponding compressive strength range of 50 psi – 930 psi. When higher compressive strengths are required, the addition of fine and less foam will result in a stronger concrete with resultant higher densities.

What type of cement is appropriate for Air-crete? Air-crete may be produced with any type of portland cement or portland cement & fly ash mixture. The performance characteristics of type II, type III and specialty cements carry forward into the performance of the Air-crete.
What are the advantages of Air-crete? There are many benefits to Air-crete in the appropriate application. It is inexpensive to produce, it has good compressive strength, it bonds well, easy to work with, self compacting, self leveling, uses less material, and offers enhanced sound and heat insulating properties. Air-crete is very easy to clean up and can be removed with only hand tools.”

More at the source: Dome Gaia

Here’s my take on this building system. First, I want to compliment them on their excellent video, photography and stunning design aesthetic. The fact that this home has been reposted on countless websites shows how popular it is. However, I do have some comments and questions:
– how thick are the dome walls? what is the R-value?
– the mixture is just cement, water and dish soap?
– it seems better to use a motor vs. burning up a good drill
– estimated time to construct the forms?
– estimated time to construct one dome with 2 skilled masons with air-crete? size of dome?
– do you use steel reinforcement?
– if air-crete is waterproof, why do you recommend using waterproofed plaster?
– how do you prevent the dome from turning black with mold in rainy climates?
– Cement products absorb moisture. Do you add something special to repel water?
– due to the specialized nature of this system, it seems best for contractors who are building lots of houses.

Video tour of Steve’s dome (stunning)
Previous blog post: Steve’s Thailand Dome Home

77 thoughts on “Air-crete Building”

  1. Hi, do you know if using the portland in air-crete will cause problems with surface mold over time? I have a mold allergy and I know that regular cinderblocks can mold up.

    • Any material can support mold growth. It is moisture that allows mold to form. I’ve seen it in between the double panes of glass in brand new windows. Best to use materials appropriately in an building envelope assembly by following the principals of building science.

        • Depends on what is needed:
          -New wall construction? Infill, structural needs?
          -Old remodel or Retrofit–if so, existing wall assembly? Climate? I don’t know the context.

          If she currently has insulated cinder block walls right now and has a moisture issue causing moldy indoor air quality, then probably look at the basics: gutter cleaning or install, downspouts piped away from house, proper grading of foundation, vapor barrier in crawl space, proper air sealing at penetrations, mechanical dehumidification, etc. If the CMU walls are not insulated or sided sufficiently, then they will be moist.

          If she’s dreaming of new home construction, then everything I just mentioned.

          Take the moisture and food away from the assembly then the conditions that support mold growth will not exist. Be careful about organic materials that are mold food (linseed oil is flax, paper faced drywall or fiberglass bats vs paperless options). Options like alkaline Limewashing, kilz, waterglass, mildewicide, mold remediation sprays, all have their places.

          If this is old work and not new construction dreaming, hiring an experienced local mold remediation company is likely the best approach.
          I’m not an aircrete advocate, unless someone is trying to fill in some awkward spaces above masonry roofs in order to flatten out the shape to properly insulate with salvaged styrofoam or something. Then I can get behind the material.

          Magnesium is more alkaline than Portland. Lime is the most akaline. But they all have different properties. I know AirKrete company foams mag aircrete in between stud cavities and that is said to be mold and insect resistant. But that’s a crazy formula to diy. This is all non structural.
          As far as new construction: Modern code compliant construction, with code compliant air tightness and exchanges, insulation levels, with rain screen siding, properly graded and guttered, and optional mechanical whole house dehumidification should be very robust in many ways including mold attenuation.

  2. We are in the process of making large foam rocks (massive) to surround our duck farm. We were inspired by Disney World’s gigantic foam based rocks. We have started making the rocks from the purple foam insulation sheets and have carved the rocks out of stacked sheets. The problem now is how to cover them to make them look like rocks and be sturdy outside. Could Aircrete be used to COVER the foam rocks, just slathered on? Or does this medium have to be used in block form? This would be so excellent as we could add coloring to it to make it look like real rocks and it would be so sturdy. PLUS super easy! Anyone tried this???

    • In university theater at Oklahoma State we made the set for Macbeth with chicken wire, staple gun and newspaper- painted over with rock coloring. I am now into burlap crete to make strong camoflage structures with the basic same idea. You will need burlap and CementAll. CementAll is 9000 psi. You can drape the burlap over the form or staple gun it into a more jagged pattern then spray or paint brush the cement on the burlap then paint or stain. It’s going to be expensive and labor intensive but really cool.

    • Aircrete is rather runny and takes 24 hours to set enough to cut and stack. I think you wold do better with a sand and cement mix to plaster your foam

  3. OK the aircrete is made and sitting in a 55 gal barrel. Now how do I get it out of the barrel? A ladle is too slow and tilting the barrel and pouring into 5 gallon buckets is quite cumbersome. How does everyone get it out of the drum? I tried using a sewage pump and the pump wouldn’t pick it up.

  4. I am adding a room to my house and wanted to use aircrete – the “foam crete” not AAC (autoclaved aerated concrete). I need some design help. How thick should the walls be? Do I need rebar?? etc. Walls would be 8 feet high – so 3 exterior walls attached to my existing house. I was going to build forms and either pour in place or make “panels” and then connect the panels. I am concerned about separation if I pour an 8 ft high section in place as opposed to making a panel with a form then standing up to connect. Would I need supports (wood posts?) to make a bearing wall – and what spacing? Then will I need (wooden) support beams to attach the roof joists?

    • Treehugger says aircrete insulation has an R-value of about 3.9 per inch, which is pretty good. (Structural aircrete has less.) If this proves correct then it could work in Alaska if you make thick walls 7″-8″ minimum. You might want to hire professionals who have high quality tools and equipment, and a proven track record. Trying to ‘wing it’ can be risky. I suggest a pitched roof design with wide roof overhangs to protect the walls.

      The simplest, lowest cost, most user friendly building method for DIYers is strawbale building. See the Straw Bale Yurt story here on our blog. You could build at roughly 1/10th the cost of aircrete if you do most work yourself, use local wood, etc.

    • Detailed in-depth searches are best done through university library online databases of academic journals. A limited number of free searches are often available if you want complete articles. Or you can get a list of journal article abstracts/summaries and then look up the articles for free.

  5. Maybe a crazy question: can you use the soap method with a clay slurry instead of concrete to make an air-clay for insulation? I am thinking in terms of adding an insulation layer outside of the structural layer…

    Like air-clay insulation outside of earthbags before earth-berming. Also thinking of using it for a mud oven with cob for the inner heatsink/structural layer, then air-clay insulation, then outer clay finish layer.

    Is foam/clay mixture viable for non-structural insulation, or would it just make a mudpie mess that never sets?

    • Sounds like it will just make a mess. But keep thinking along these lines and maybe you’ll think of something that will work.

    • The problems you may encounter with this in the main will be setting time. Clay typically takes days or weeks to “cure” and harden, also it will not act like concrete where a chemical change takes place, turning from powder to solid material. So physically clay, will not change state fast enough, so the bubbles will disperse before a fixed state is achieved. I think this will be the problem, the other fact is if you use a clay/cement mix. again even with the use of a latex bonder. or caulk mixed into the foam I think it will not provide a fast enough setting time.

  6. I’m new to the hole dome idea. It is fascinating to me and I have an idea that I would like to propose. Unlike the traditional monolithic dome concept where a balloon is used as a form and insulation sprayed on the inside of the balloon.

    My idea would be to modify the balloon so that is is two ply. The inside layer would be used to inflate the dome and aircrete would be poured between the tow layers of the balloon. Once the aircrete is set re bar could then be installed and shotcrete applied over the re bar. This would eliminate the need for foam and possibly reduce the cost of construction and provide a greener solution.

    • Your method would have two poorly connected layers so it wouldn’t be as strong as the current method. A strong connection between the rebar and concrete is critical. Also, inflatable forms like companies are using now are reusable. You could only use your form one time, right?

      Not all methods use inflatable forms and not all domes are monolithic shaped. There are lots of methods and shapes.

      • With a monolithic dome the balloon is inflated and then the inside is sprayed with foam. The balloon is not removed as I understand it. The layers would not be anymore poorly bonded than the foam and the concrete layer. The Idea of the aircrete would be to provied insulation not so much for support. However it would provide more support than foam. The shotcrete would be applied over the rebar in the same manner it currently is. Its sprayed on after the layer of foam and re bar are in place.

          • The purpose of the balloon form is to give the dome its shape. Its inflated and sprayed with foam. Its the reason they use a balloon or
            there would be nothing to spray the foam on. The balloon form is inflated and sprayed with foam. Then re bar is installed and covered with shot crete. My idea is to eliminate the foam and replace with aircrete. I think its a superior material

  7. I would like to get contact information, if anyone has it, for finding an Air Crete Builder here or outside of the United States. I would like to have our Retirement home build from Air Crete. We desire to have a one-story home around 3,000 square feet with 1-2 other structures on the property for entertaining, outdoor kitchen, etc.etc. I would be willing to negotiate with the builder/designer to advertise our home to further their business opportunities. Could someone please help?

  8. Retired and tired so need information of an alternative company in Arizona that could build us an Aircrete home on our property please.

    • Air-crete is not common yet in the US. Your best bet is to search for companies online using a variety of different search terms such as lightweight concrete house, insulated concrete house, etc. There are numerous competing methods and products now.

  9. Where can one go to learn how to do this get a class pay for the class in the USA or abroad please let me know thank you yours coming up in Hawaii would not be available for me because of time obligations

  10. From Chris:
    airKrete company uses aireated magnesium cement. They foam stud bays and between multiple masonry wythes. Good claims, cool YouTube videos on it.
    Aircrete can be many things depending upon density, compressive strengths, reinforcements, binders…

  11. I need a lot of help in providing some information on an idea that I have.
    I am manfactureing Tubular Structures for all kinds of uses as well have copy rights on doing such. I am building a steel tube to the exterior and and interior tube to the inside and filling the void with foam. Problems: My basic residential tube is 25ft. in dia. 24ft8in on the interior and the length is 54 foot long. Suspending these heavy metal tubes inside one another is costly and very hard to complete. I am working on another idea. Replace the interior tube with 5ft.x 12ft curverliner foam/cement panels instead. go to my web site: International Steel Structures. or my email if you think you can be of any help what so ever. or call me.

    • Where can i find detailed information on building with aircete? I lots of questions like; can the foam be mixed into a conventional concrete mixer? Is rebar needed or prefered? What mixes ar needed for different structual needs? Bond beamsetc?

          • We answer tens of thousands of questions for free. I don’t have time to search out every answer for every question. Once in a while I throw the question out there for others to pitch in. That’s not a useless answer. It encourages group participation and self empowerment. Virtually everything people ask here is available free online. Don’t rely on someone to do all your work.

  12. I’m planning on building a large two dome house and was wondering if it would be feasible to use aircrete. Dome one will be 35ft wide, 26ft tall, and dome 2 will be 35 ft wide, 17.5 ft tall. I’d like to use fiberglass rear for a frame, wrap that in chicken wire, and apply aircrete to the inner and outer part of this frame so the rear will be the center of the walls. Is there any reason not to do this? And if I do, how thick do you think I should make the walls?

  13. I’m a single mom interested in building a home for my family. Do you supply the steel? Or how can I get steel? Lowes or home depot? After buying you green machine, do you give an itemized list of everything needed to put this together, including power of drill needed? Instructions for foundation, maybe some simple floor plans? I’m not a construction worker or engineer. Is there someway to give details to make this as simple a possible? Also details on preventing cracking and molding. What Products to use and where to buy products. Thank you for your time and feedback in advance.

    • If you do not have a lot of experience with construction, DO NOT TRY THIS AT HOME! There are many pitfalls in this method. I’ve only been exploring this construction for a few hours, and the problems I’ve seen with this homemade setup are many. You must understand concrete – things like water-cement ratio are extremely important. You can end up with a house that the big bad wolf can blow down… or a little thunderstorm.

      • Yes, that’s right. Air-crete products are widespread and well proven in countries like Germany. But that’s way different than trying to do this at home with imperfect methods. You have to do your homework just like anything. We offer it here as just one more interesting option to consider.

      • Just have do do some research…it is not rocket science if you follow the basic mix guidelines and structural dimensions required for the job. Your house will not fall down if you are thorough.

  14. i watched one video of a man who was experimenting with making air-crete and his molded pieceses where very prital and did not have no 9000 lbs of structural strength did he do something wrong he also tried to use 100 psi instead of 60 psi air presure in the foam why was his aircrete so brital???

  15. Greetings!

    I am wondering about the sound proofing of the Air-Crete Domes? With walls that are 4″ thick, what are ways i can create more soundproofing (I will be constructing a dome for a recording studio).
    Thank you for your time and response!

    • Lining the walls with “soundproofing will only block or absorb the high frequencies, allowing all rumbling noises to pass thru the walls. A hi mass wall will block the hi frequencies – you would want thick, dense walls. A double wall can also be effective in blocking the low frequencies.

      • Is there an exterior coating that will dampen rumbling noises as well as help protect walls against moisture damage?

        • Concrete is the best material for dampening the low frequencies. You must have mass – that is, something that weighs a lot. Several layers of drywall are used in conventional construction.

    • Domes are never conducive to audio performance. They produce the worst form of harmonics, frequently expressed as the “fishbowl effect,” or the rotunda-effect in classical literature. But, this is not necessarily the death-knell of a cleverly designed structure.

      Let’s look at the best of the best working studios in the late 1990’s, before digital-direct recording went mainstream. This evolution, BTW, was dependent on stripping-away the vial harmonics we get from actual instruments played in free air. In geek speak, “record everything as dry as possible!”

      A standard rectangular floorplan was often bettered by building a divider-wall running the long side, deliberately set off square. This becomes a hallway, with an area for gathering at the entry, or far end. Across the ceiling, placed at what appear to be utterly random angles and intervals, they suspend single sheets of acoustic tiles at elevations from 2″ away from the ceiling to 2′ below the ceiling. This breaks up standing waves.

      Demonstrably, we’ve crated a horn form that is stuffed with a couple of socks. Next, we look at where the pressure of this horn form is aimed to go. And, we observe the rule that “an open window provides the best acoustics.” -This means is that you simply need to evaluate WHERE those pressures are likely to go.

      This leads you to embrace the Helmholtz resonator, known by most as the Bass Trap. And, this brings us back to all those the former considerations of working within the confines of the fishbowl. Now, we see it as just part of an operative schematic flow.

  16. Family thinking of building a few of these.

    “cracking” was mentioned. How extensive? would adding fiber prevent?

    Can this stuff be used as the footing/slab/floor and the dome on top?

    Can it be cut partially buried into a shallow hillside maybe 3-5′ high on the earth buried side?

    Our potential land has no flat building areas. I was thinking of cutting back into a hill and constructing a dome and replacing the soil so the dome just comes out of the hill. My main concern was how to waterproof the structure. Having found aircreat, I am very excited about the possibilities.

    • Yes, synthetic fiber will reduce cracking. Check with the air-crete company in the video and use what they recommend to make sure it flows through their machine okay.

      I would not use air-crete wherever there are high stresses like foundations and walls that hold back soil unless a licensed engineer studies all the details and comes up with a safe design.

      One option is to build gravel bag retaining walls and ‘stair step’ the building site. Then build the house on the terraces you’ve created. Again, get some professional input because building on slopes is tricky. Your whole house could get washed down hill during a heavy rain. Add extra retaining walls with French drains above the house as needed. All of this adds lots of time and labor so plan carefully.

  17. Hajjar
    Read your article on air-crete.
    1) What is the weight of the entire machine to produce air-crete? I would be taking it overseas.
    2) Have you done comparison cost to for example to cinder block per sq foot or sq meter?
    3) Can air-crete blocks be used to build something similar to a conventional house?

    • Scott, aerated cement blocks are standard. They’re quite popular because they’re light and easy to work with plus the air bubbles add insulation. Usually they are autoclaved. The heat treatment and cement content put them down the list of green materials in my opinion.

    • Hi Scott,
      I don’t’ have the exact weight available at the moment, but it’s about 30lbs, filts in a 15″x10″x42″ box. Light enough and small enough to ship via USPS. It cost $150 to airmail one to Australia recently. That excluded the drill.

      2) Have you done comparison cost to for example to cinder block per sq foot or sq meter? No I haven’t
      3) Can air-crete blocks be used to build something similar to a conventional house? Yes, it’s common and there are companies casting large panels for conventional houses.

  18. Thanks for your compliments, comments and questions Owen.
    – how thick are the dome walls? what is the R-value?
    The walls can be made any thickness. Our Thailand domes were about 10cm (4″) thick. There’s many variations of Air-crete. I just posted an article about R value on our website. here’s the link
    – the mixture is just cement, water and dish soap? That’s right.
    – it seems better to use a motor vs. burning up a good drill. It’s not hard on a high torque, low speed 1/2″ drill. The mixture is light weight. A gear motor cost as much or more then a drill and a drill has multiple functions. It operates Bender for example.
    – estimated time to construct the forms? An arch form can be built in a day. The entire dome takes several day.
    – do you use steel reinforcement? we use steel reinforcement below the center line of the sphere and around the skylight opening.
    – if air-crete is waterproof, why do you recommend using waterproofed plaster? The surface is rough, it can crack. It’s best to finish it with at least a coat of latex paint.
    – how do you prevent the dome from turning black with mold in rainy climates? We finished the dome with mold resistant paint.
    – Cement products absorb moisture. Do you add something special to repel water? We don’t but a person could add any cement additive to air-crete.
    – due to the specialized nature of this system, it seems best for contractors who are building lots of houses.
    Our equipment and Air-crete is inexpensive and it requires only a modest amount of labour. The possibilities are endless for a DIY builder.
    I hope this answered your questions. all my best, Hajjar

    • Hajjar, im getting a 404 error on your website link. Is there a new site or have you guys stopped using your site?
      Thanks for all your wonderful and inspiring work – you too, Owen! I’m a big fan.

      • The video has been cut but their website is working for me:

        Hajjar, did you guys cut the link to the video? We try to promote other sites but when there are broken links like this it works against us in Internet searches.

  19. Please let us know when you get your comments and questions answered Owen. I as well am very interested in learning more about this concept. Thanks and good work amigo!


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