Climate’s Affect on a Bale House

There’s no question that your local climate will have a large affect on your home, whether it be a bale home or a home made of concrete block. In fact, the climate is often a driving force in people’s decision to build with bales. I’m sure you’ve heard people talk about how hot their climate is or how cold it is and how if they only had a more efficient home, they could better stand the extremes. Unfortunately, some people decide to build a straw bale home before they consider the potential affects that their climate could have on it until its too late. It’s important to know what might happen to your home before you build it because there may be steps you can take to minimize those affects if you plan ahead.

Below are some of the affects that climate has on a bale home. Some of these may seem obvious while others may not. I’m sure I’ve missed some, so feel free to add your own in he comments section.

  1. Rain can saturate walls if they are not properly protected. You may have heard the saying “Big Hat and Big Boots” referring to a good roof overhang and a large raised foundation. These are two very good ideas if you live in an area with high rain totals. Also consider adding a waterproof membrane above the bales, just below the bale stop or box beam. The challenge is avoiding punctures in this membrane during construction. Make sure it laps over the edge of the bales a couple inches. Too little overlap and water can still make it down into the bales. Too much overlap and your plaster will not adhere to the bales at the top of the wall.
  2. Humidity, unlike rain, cannot be designed out of the equation with a hat and boots because it permeates everywhere and it can cause moisture to build up in the walls if not handled properly.  The best approach to high humidity is two-fold. First, build with quality materials that can help in removing excess moisture from your air/wall interface. Hygroscopic plaster such as lime or earth is a great idea as it will naturally help keep a constant moisture level in the wall. If there is excess moisture in the air, it will absorb it and hold onto it (until it reaches saturation of course). Once the air dries out below the level of what the plaster is holding, the plaster will release the excess moisture back into the air. The second approach is a mechanical one. Install an Energy Recovery Ventilator (ERV) to help keep the air in your home fresh and to remove excess moisture. These are simple to install and work very well. They are also very energy efficient. Don’t rely solely on them as anything mechanical can fail (power loss, broken parts, etc) so be sure to use them as part of the two-fold approach.
  3. Cold weather can have all kinds of impacts. One that is often overlooked is the condensation of moisture in the walls. Because cold climates require us as humans to heat our indoor air space to stay warm, we create uneven climates from one side of a wall to the other that are quite drastic. If the warm and moisture laden air from the inside of the house pushes into the center of a bale wall where everything is cold, the moisture can condense on the straw. The best way to win this battle is to not heat your home and live in the cold. Not very likely option I suppose, so another plan of attack is to make sure you seal any penetrations into the wall and seams between the wall and other surfaces. The most common areas are around electrical and plumbing installations and at the floor to wall and wall to ceiling transitions. Be sure to pay special attention to these areas and you’ll be fine. Use foam gaskets at the electrical and plumbing installations and vapor tape and/or caulking at the wall to ceiling/floor transitions.
  4. Hot climates pose their own set of issues. Of course, hot climates that are associated with high humidity must be approached in accordance with #2 above; however, dry climates have a different set of concerns. One that is often not considered is the life of the plaster. Natural plasters are not built with chemicals designed to help them resist cracking and thus must be installed carefully. Be sure to plaster the house when it is protected and ONLY then. Hang tarps from the eaves so that you can plaster in the shade and out of the wind. These two aspects of a hot and dry climate can ruin a plaster job. Keep in mind that your plaster is not only the “look” of your house, but also its protection. If it is compromised, so too is the substrate, in this case, your bales.

Like I said at the beginning of the post, this list is in no way complete. There are many other climates that should and will be considered and many other affects of each of those climates. This is a list to do one thing: get you thinking. I hope it does just that. As always, I welcome your comments and input.

14 Responses to Climate’s Affect on a Bale House

  1. Jamie McKay, P.Eng. Wed, November 9, 2011 at 9:22 am #

    Thanks Andrew – this is a big issue and difficult to summarize into a short post. I, as an envelope consultant and owner of a post/beam strawbale infil, am constantly asked if straw makes sense for clients.

    I agree with the “big hat, good boots” philosophy and the air leakage control (especially as people push the boundaries of design and the climates of use). I think that people must understand one big point, which is that of “breathable wall design”, which means vapour movement, not air. Vapour movement means that there is no vapour barrier and vapour diffusion can move from inside to out or vise versa. Strawbale walls typically act on a “storage and release” basis, meaning that the materials will store an amount of moisture wihtin the materials, and then release them when conditions change. This works, as long as the storage is sufficient and the release is timely. As for air leakage, no amount is good, but some amount is tolerable (storage and release basis again). So, Owners/builders please make sure that you review the edges of your exterior walls and use fans in Kitchens and bathrooms to keep the source moisture down.

    Cheers,

    Jamie.

  2. Andrew Morrison Thu, November 10, 2011 at 8:14 am #

    Absolutely Jamie. All good points, clearly made. Thanks for that.

  3. Kallee Fri, November 11, 2011 at 5:03 am #

    Hi Andrew, great website! I live in Nova Scotia, Canada. We have long wet, snowing winters, long rainy springs and moderate summers. Would a straw bale house survive our climate or am I dreaming?

  4. .Ellen Ronis Fri, November 11, 2011 at 5:06 pm #

    I live in the Northeast upstate NY where all those climates are not only possible but likely. It sounds like there are solutions to all the issues but does it make sense to build with straw Bale if you have to keep putting out fires, so to speak?

  5. Andrew Morrison Mon, November 14, 2011 at 1:57 pm #

    Definitely, especially where you are. The moisture (humidity) that you speak of is not a big problem. I’m referring to places like Georgia and Florida when I mention high humidity. There are lots of straw bale houses in Eastern New York. I have done three workshops there as well (NY State). In Hurley, Bainbridge, and Cuyler. Perfect locations as far as I could tell.

  6. Andrew Morrison Mon, November 14, 2011 at 1:57 pm #

    Indeed. In fact a friend of mine just build one there. It will take some detailing, but can work.

  7. Amy @ Six Flower Mom Thu, December 1, 2011 at 5:45 am #

    My family and I are planning to build a house, it has always been my husbands desire to build straw bale. We live in Southern, Central Kentucky and I am concerned about our wet, humid, every changing climate here … do you feel that this is a good location for straw bale or not? I am reading the challenges above and feel like we would have to deal with all of them, I am very nervous about this. Just seeking advice!

  8. Andrew Morrison Sun, December 4, 2011 at 8:22 am #

    Hi Amy. We have built homes with success in Tennessee, Florida, Georgia, and other wet climates. You will definitely need to pay attention to the details and add some mechanical dehumidifying details to the design. Check out this link and talk to the folks there as it may be helpful for you to talk to people in Kentucky who have actually built.

  9. Susan Wed, December 7, 2011 at 8:29 am #

    Hi… I have always dreamed of building strawbale someday, and I thought this would happen in the Texas Hill Country…but…life happens and we have found ourselves in Florida instead! Must I give up my strawbale dreams? Can I still build my forever home here with strawbale? Please advise!

  10. Andrew Morrison Wed, December 7, 2011 at 2:59 pm #

    Hi Susan. It is not as easy in high humidity areas, but it can still be done. You’ll need some extra detailing to handle the humidity, but keep smiling!

  11. Gail Thu, December 29, 2011 at 3:04 pm #

    Hi, My neighbor owns (vacant) rental property next door and has his poor dog outside in a piece of crap dog house, that’s surrounded by mud and water. I started feeding it/playing with it. Now, it’s whimpering during the nice in the 14 degree weather. I can’t afford a insulated dog house. I’m in Pittsburgh, Pa. Can I build a cob house in 40 degree weather?

  12. Andrew Morrison Mon, January 2, 2012 at 2:55 pm #

    Hi Gail. The dog would be better off with a straw bale house as cob does not insulate, it is thermal mass. Meaning that if it´s cold outside the cob house it will be cold inside the house unless there is a heat source. A bale structure will provide insulation and the dog´s body heat (assuming you include a door) will be enough to warm the space. Good luck.

  13. david snow Mon, August 19, 2013 at 9:17 am #

    Thank you for the update.

  14. Church Thu, November 13, 2014 at 4:49 pm #

    Hi A,
    We R presently building a passivise solar straw bale house in Halifax area of Nova Scotia. I have been viewing your videos on U tube and have found them to B helpful Thank U

    ” C “

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