ModCell Construction: Straw Bale Modular Company

Written by Andrew Morrison

ModCell Construction large structure
ModCell Construction has come up with one of the coolest and most beautiful straw bale construction concepts I have seen in a long time. Although not something for the owner builder per se, this technique makes the potential for commercial straw bale construction a reality and can even be used in residential applications if the site location and project scale are right.

ModCell Construction structure
The overall beauty of the finish product is amazing enough, but couple that with the fact that the building is carbon negative, not carbon neutral, and you have a super insulated, beautiful, and environmentally responsible building. Even the factory that makes the panels is mobile, thus reducing the shipping impacts of the panels once they are manufactured.

All in all, I think this product could have a large impact on the way commercial buildings are built. I certainly hope it does. I strongly recommend that you check out the website for this company at There is a cool slide presentation on the overview page that is worth checking out to see how the process works from start to finish.

17 Responses

  1. this looks like it could be modified to for residential use. pre-fab your own home or out building or am i overlooking something or wishfull thinking?

  2. I think it could be Gary. The only issue I see is the cost to mobe the factory to a nearby site. If the home is too small, the cost of that might overshadow the project. Hopefully the folks at ModCell will comment directly on this blog to answer these questions. I hate to make assumptions about some one else’s project.

  3. Hello
    If you go to the ModCell website and look for the BaleHaus on the projects page, also in photo galleries. This is one design for a house using ModCell. Ideally we would lime to do 5 or more houses in on one site. This helps us ensure that we can viably set up the Flying Factory. However we are speaking to a number if people about one off homes. We are very happy to discuss any project. The ModCell panel was developed primarily by an architect. As such we have the in house expertise to help you plan the home.
    We also built a house live on TV over 6 days. We had to slow down so the camera crew could keep up. Left to our own devises we could have structurally built it in 2 days. This is also on the websit.
    I hope this answers your question
    Finlay White

  4. This a very cool concept that I will have to look into further. Thank you for providing us with such great info Andrew it really helps to try to stay on top of the green building wave.

    Real quick question on another note. I am retrofitting a straw bale structure that was never plastered on the inside. New owners own it now and want sheet rock inside. I know i have tried to talk them out of it. My question is do I need to put a scratch coat of plaster under the sheet rock? I was planning on it but don’t want to do all that work if it is not necesary.
    Thank you for all that you do.
    Heirloom Construction

  5. Thanks Jordan. If you can get the drywall completely tight against the bales then you don’t need to plaster; however, this is almost impossible to do over the entire wall surface. I would do at least a quick slip coat of earthen plaster if you can.

    On another note, how do you plan to deal with the window wells with drywall? That seems daunting to me in terms of making it look good. Let me know your plan as I am curious.

    If you can, talk them out of the drywall idea. It is not a good plan. Drywall is inferior to plaster no matter what the building type. Plaster is much stronger and can have a much more quality finish to it than drywall mud. I think they really should change their mind. My 2 cents (ok that’s more like 90 cents, but you get the idea).

  6. Andrew,

    I’m new to straw bale, so forgive my naivety…but wouldn’t you just make the window bucks a little wider, attach a furring strip around the buck and screw the drywall to the strips. Then trim out as normal?

    Thanks, love the site.

  7. Doug, the issue is that the bales are not flat and square, especially around the windows. It is all but impossible to get a clean finish with drywall here. It can be done, but you end up with very sterile looking window wells as opposed to the organic style of the bale construction. It’s a case of: “If you want a conventional look, you should build with conventional materials. If you want the advantages of straw bale, then you should plan on the look and feel of straw bale.”

  8. Hello Andrew and fellow straw bale construction devotees
    Some news about ModCell.
    We are currently building a two storey BaleHaus at the University of Bath. The building is constructed using ModCell pre-fabricated straw bale panels. We are reusing the panels previously used for a TV project we were on involved with last year. This was called ‘The House That Kevin Built’ (THTKB). Kevin is a well known TV presenter here in the UK. Anyway, the ground floor of THTKB is now the first floor of the new building. I think this clearly shows one of the advantages of pre-fabricated straw bale panels. The new house, the BaleHaus, is being constructed to allow us to continue our research. There are over 85 sensors in the BaleHaus that will record data on the performance of the ModCell panels and the environment within the house.
    At the time of writing we are in week two of the build. We managed to build the main structure and roof of the building within 4 days. Now we are waiting for the glazing and timber cladding to arrive and be installed. If you are interested there is a live strawcam showing the build as it progresses. go to to find out more. This includes photos of the build as well as the strawcam link.

  9. While I love this idea, I keep asking myself what’s its advantage over SIPs? If you look at the amount of lumber used for the ModCell framing, you’ve easily got the equivalent of a standard stud wall, one you could insulate with soy-based iso insulation.

    I see the advantage of carbon sequestration, but I need to better understand why I would want to do this from both an environmental and economic perspective.

  10. Bill

    Thanks for the challenges, below are some answers, I hope:

    The ModCell frame uses less lumber than a stud frame wall of the same depth. The ModCell system takes the lumber and moves it to create a structural ‘picture’ frame into which we infill with straw and lime render. We end up using 13% less timber for the same surface area of wall.

    SIPs are excellent solutions and can deliver high R/U Values. However they result in a thermally lightweight building, which is great in winter but not so good in summer. Thermally lightweight buildings tend to over heat in summer requiring air conditioning to be engaged.

    ModCell is also thermally massive. Thermal mass slows down the response times of a building to overheating. The research at the University of Bath shows that ModCell has a thermal lag of 13 hours. This combined with the lime render and solid timber means that a BaleHaus stays cool in summer as well as warm in winter.

    Soya foams still use polyurethane, the soya is a small part of the agent that catalyses the foam reaction. Polyurethane (PU) is mainly used in insulation and soft/foamed products. It uses several hazardous intermediates and creates numerous hazardous by-products. These include phosgene, isocyanates, toluene, diamines, and the ozone-depleting gases methylene chloride and CFCs, as well as halogenated flame retardants and pigments. The burning of PU releases numerous hazardous chemicals such as isocyanates, carbon dioxide, hydrogen cyanide, PAHs and dioxins.

    The straw used in ModCell is a by product of the agricultural industry ie it is not grown to perform as an insulating material. For example, in the UK 3m tonnes of straw is generated as a by product every year. It used to be burnt in the field, now outlawed, and today is predominantly used as animal bedding.

    Even if every new house in the UK were to be made using ModCell, it would only use 1/5th of the available straw each year. The figures for wheat production in the US are of an order of magnitude higher!

    Soya crops, if not sustainably managed, can have serious environmental impacts. The whole food/biofuel debate, for example.

    So why use ModCell?

    It’s carbon negative in manufacture.
    Reduces heating bills by up to 85%.
    Reduces CO2 emissions by 60%.
    Uses local skills, labour and material.
    Creates homes that are beautiful, affordable and sustainable.

    The cost of ModCell in the UK is market driven. The enormous timber framed market in America would mean the unit cost of ModCell would be less than in the UK!

    We hope to be coming to the US soon to find partners to work with.

    Watch this space!

    Best regards

    Craig White

  11. Hi. Great site. I’m wondering just how large a Southern California straw bale structure can be….big enough to build a gymnasium, for example (court is 94 x 50 feet, or 29 x 15 meters, plus perimeter)?

  12. Hi Lauren. With the proper engineering, you could definitely build a large structure like that. Let me know if you want to move forward and I can recommend some architects/designers and engineers.

  13. Do you build in the US. Everything seems to be in UK. I am very interested in building a passiv haus standard straw bale home. Thank you.

    Ellen Smith

  14. Hi Ellen. That’s probably a better question for the ModCell folks to answer. I have been in touch with them for some time and they have specific plans to build here in the States although you are correct that most of their work has been done in the UK to date.

  15. Hello, I’ve been doing some research regarding strawbale construction and have particularly noticed the trend of prefabricated strawbale construction here..
    What are the actual benefits and limitations of prefabricated strawbale construction compared to in-situ load bearing and in-fill forms of straw bale construction?
    And how would these relate to different building sectors..e.g Schools, office buildings and domestic sector houses on the other hand?
    Where can I find more info on this?
    Thank you.

  16. Hi Jeff. Prefab panels can be great in the right situation. I have to admit that I am not the expert when it comes to prefab. You would be better off contacting the ModCell guys directly. I like what they have shared with me, although it is certainly not for the owner/builder.

  17. Reference to Jeff Kayina’s question
    HI Jeff,
    I work for ModCell, so hopefully can answer some of your questions about pre-farication of straw bale panels.
    We have now been involved in a number of schools, Colleges and University buildings (9 so far with another 3 to start in early 2012) together with commercial, and residential. This includes just completing a 2,900m2 business centre and we are about to start building 20 new homes. See for projects.
    By prefabricating the panels we are able to assemble the the buildings in a very short period of time on site. An 800m2 school building had the structural panels installed within 7 days. This is ideal and allows for a much shorter time on site than traditional methods of straw bale construction.
    By prefabrication the panel it also goes a long way to removing concerns developers have about using straw including: Fear of fire risk, our panels have been awarded a 2hr15min fire certificate.
    Manufactured using modern methods of construction and offering factory controlled quality standards.
    Building control are happier knowing the panels are all of uniform quality and standards.
    By having a panel that is replicable we are opening the way for the use of straw to become mainstream. We are in talks with four of the top five supermarket chains in the UK. We haven’t approached the fifth one yet.
    We are approached from countries all over the world on an almost daily basis to use our panels (which are patented). We are looking to expand outside the UK in the coming months via Licensing, Franchising and/or Joint ventures.
    I hope the above goes some way to answering your question. If you need more information or just want to chat then drop me an email (assuming it OK to do this) at [email protected]
    All the best, Finlay

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