Tropical Climates and Straw Bale Construction

Do you live in a Tropical Rain Forest?

tropical houseI am a big believer in the merits of straw bale construction. That’s probably obvious by now; however, there is one major drawback to working with bales: climate conditions. Bale homes are ideal for dry and mostly dry climates, acceptable in wet climates, and difficult to deal with in very wet and humid climates. So what about tropical climates and straw bale construction?

The big demon is not water, in the form of rain at least. In stead, it is humidity. Rain can be handled with proper design so even the wettest climates can accommodate straw bale structures. Humidity, on the other hand, cannot easily be designed out of a structure. It pervades everything and gets into everything. A bale house can stay dry from rain and still be saturated with moisture inside the plaster due to the acclimation of the bales to the area’s relative humidity. Everything eventually settles on a moisture content that is in direct relation to the relative humidity of its surroundings. Therefore, if the humidity is high, so too is the moisture content of your bread, your clothes, and your bales!

Let me give you an example, I used to live in Northern California, where humidity was often very high due to the coastal fog. My wife put her leather boots under our bed for a month and when she took them out, they were covered in green mold! Our house seemed fine and we surely did not expect to see that kind of mold anywhere near the inside of our house. But, the space under the bed is dark and has limited air movement, kind of like the space in between your layers of plaster.

What to do? Well, you must first consider if your climate is right for straw bale construction. If you have really high humidity and very little dry season each year, you may want to consider something other than bale construction. Another option is to consider mechanical help. If you install a whole house de-humidifier, you can minimize the amount of moisture in your house and therefore in your bales. Remember that when pressurized under normal living conditions, air moves out through the walls. If the air is dry, it is safe to pass through the walls. Systems like this can be installed into your HVAC system, if you have one, or can be stand alone units utilizing 4″ duct work.

Remember to design and build for the water and humidity. You not only need to design to keep water out, but also to allow it to escape should it get in (nature has a way of blowing even the greatest plans!) Plan for both, and you will be okay. Nevertheless, if you live some where that you think is too risky, ask for advice and then make whatever decision you feel is best around the use of bales in your home. And know that this is coming from some one who loves bale construction so I’m trying to talk you out of your dream!

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59 Responses to Tropical Climates and Straw Bale Construction

  1. Andrew Morrison
    Andrew Morrison Fri, March 26, 2021 at 12:03 pm #

    Hello Kitanega. I am not familiar with the Ugandan climate, so I am not able to comment from a place of clarity. That said, I have built houses in many different climates, including very humid areas in the US with success. Much will depend on the design details and the construction execution. If you have a dry season during the year, that will usually be enough to “reboot” the bales for another year of rain and humidity. If, on the other hand, it is always either rainy or humid (or both), straw bale may not be the best option for you. TO give you an idea of climates that have worked for straw bale in the US that might seem to humid or wet, please consider the successes we have had in places like Arkansas, West Virginia, Virginia, Texas, Tennessee, Missouri, Oregon, Washington, Iowa, and Georgia. I hope that helps.

  2. Avatar
    Matthew Ponsano Thu, July 1, 2021 at 10:46 am #

    I live in Sarasota Florida about mid state.
    It has a dry season (winter) and a wet one (summer).
    Buying a conventional house is beyond my financial means.
    But is it dry enough in total enough here for a bail house?
    What is the minimal amount of yearly dry air required to make my bail house a reality?

  3. Andrew Morrison
    Andrew Morrison Thu, July 22, 2021 at 7:27 am #

    Hi Matthew. That’s an impossible question to accurately answer. “Dry enough” will be totally relevant to the house, the solar exposure, access to dry wind, etc. I should also note that if the main (or only) reason you are building a straw bale house is to save money, you are going to be disappointed. Bale houses are actually a bit more expensive to build than conventional houses when comparing the homes by size alone. They are very labor intensive to build, and labor is expensive. The savings come in the long-term holding costs of the house because they are SO inexpensive to operate (heating and cooling costs, etc.).

  4. Avatar
    Bruce Sun, August 1, 2021 at 11:55 am #

    Hi Andrew,
    I love this site. And your passion is unmatched. Thank you

    I have a question, I live in the Highlands of Panama, about 2500′ up. It rains and is more than 80% humidity for 7 months and is windy (more than 20mph) throughout the other 5 months. Also, fires crop up during the 5 month dry season.

    Is it even possible, doable to build a strawbale house? Or do you think I should stick with brick n mortar, and tin.?

    Thanks again,

    Bruce

  5. Andrew Morrison
    Andrew Morrison Mon, August 2, 2021 at 8:28 am #

    Hi Bruce. Thanks for your kind words. The biggest issue would be the humidity as moisture is tough for bale structures. That said, if the house has 5 months of dry season, I don’t expect there to be a problem. High winds and fires (although a terrible combination) are not a big problem for bale structures. They are very fire resistant and can handle strong winds if designed and built properly.

  6. Avatar
    Charles Sabourin Thu, October 14, 2021 at 10:54 am #

    Andrew, ordered your videos. Very informative and thorough. Looking to build a compression round house in Suwannee County in north Fl. Was originally going to build a hyper adobe house, but there seems to be more precedent for Bale houses getting through the permitting process and Bale walls go up much faster. With average humidity between 60 and 70 percent, and no dry season to speak of, is it even feasible to build with bales and if so, what mitigating options can I implement to deal with that issue to avoid it being a problem? Thanks.

    Charles

  7. Andrew Morrison
    Andrew Morrison Thu, October 14, 2021 at 4:04 pm #

    Hi Charles. I would be concerned about that level of humidity. You might be okay if you added a mechanical system to remove excess interior moisture, but it feels pretty risky to me. I’ve never built anywhere with that level of constant humidity. If you had a dry season, that would be diffrent.

  8. Avatar
    Nicole Mon, November 15, 2021 at 1:01 am #

    Hello
    I am learning a lot from your site and am interested in straw bale construction for a small unit. I’m in West Auckland, near the Waitakere Ranges in NZ, however, where the weather is very unpredictable. It can rain on and off in a day, or look like rain but then not rain for days, and then there will be thunderstoms out of nowhere and the rain coming in sideways (I stopped paying attention to weather reports when I moved here – there is no point, they are rarely right!). Sometimes it is very humid but not like Florida humid, and sometimes it is very hot, but it never gets below maybe 40F in winter.

    From what you have said to others, Auckland is probably safer than really highly humid places, but I really don’t thing we’d get a solid block of time to build anything without risking it all getting rained on – potentally sideways so even a good roof wouldn’t be that helpful. Should we maybe think about cob or something instead?
    Thank you!

  9. Andrew Morrison
    Andrew Morrison Mon, November 15, 2021 at 10:24 am #

    Hi Nicole. That sounds like a challenge, but nothing that should stop you from building with bales. You would just need to protect the build site during construction by using tarps. Simply attach them at the top of the wall, under the roof line so roof water drains OVER them, with a solid piece of wood so that the connection is sturdy (wrap the tarp around a 2×2 and then screw the 2×2 to the house frame). Roll the tarps up and attach them at the roof with a piece of baling twine or some other material that would allow you to quickly release the rolls when it starts raining. At the bottom of the wall, you can have attachment points for the bottom of the tarp (again, wrapped around a 2×2) such as metal concrete form stakes driven into the ground with safety caps on them. You could then drill holes in the 2×2 that would allow you to slip the tarp frame over the stakes, slide a pin through the stake holes to secure the tarp to the ground. In this way, you can pull the tarps back from the wall and continue to work underneath them.

    No matter what type of construction you choose, the rain will have an impact, so rather than have the rain become the determining factor of what you build, I suggest you build what you really want to live in and then adjust to manage the rain as needed. Hope that helps!

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