Debunking the Rodent Myth

I know, I know…For most of you this is old information, BUT if there are any folks out there that still have a worry in their minds (and it’s OK if you do!) about straw bale houses and rodent invasions, this latest “Straw Bale Minute” is a must watch. Trust me, rodents would much prefer to set up residence in your neighbor’s conventionally built house with lovely pink insulation than live in straw bale walls. You can hear why in this “Minute” below:


Want to learn more about straw bale houses and how to build one? Want to do so for FREE? Sign up for our totally free 16 Day Straw Bale eCourse! Find out more HERE.

16 Responses to Debunking the Rodent Myth

  1. Avatar
    David Knapp Mon, January 27, 2014 at 4:30 am #

    Our strawbale house only had mice issues in the conventional constructed areas where they came down through the roof into the utility area and also into chase areas under tall windows where they construction a boxed in area. Any place of regular straw bale construction & practices had no mice issues at all. This was a big lesson learned & what can drive you crazy trying to secure conventional built sub-areas. We learned what we will do differently on the next build.

  2. Avatar
    Andrew Morrison Mon, January 27, 2014 at 7:57 am #

    Thanks David. I bet folks would be interested to hear what you would do differently if you feel like sharing that too…

  3. Avatar
    Lisa Burroughs Mon, January 27, 2014 at 8:05 am #

    Liked the mice rodent info. Here is my question. We have land in Cibolla National Forest near Magdalena, New Mexico and it is populated with several different rates/mice. You have answered part of my question but the other is the storage of bales at the site, and while they are stored they acquire livein rodents. Also say we are working on site and our bales are sitting around open on one side to the elements (not coated yet) and the desperate critters get in then? Would you say at this point the answer is the fact that the bales are so dense it would be nearly impossible for them to enter?

  4. Avatar
    Andrew Morrison Mon, January 27, 2014 at 8:09 pm #

    In a loose stack of bales, you will get some rodents, i.e. when your bales are waiting on site to be used. They will make little nests in the space between the bales and may even scratch and chew out a little depression in the top of a bale as a nest. They won’t, however, cause serious damage to the bales. Be sure to stack the bottom bales on edge so that the twine is not on the bottom of the stack. Rodents have a knack for chewing those strings (where they meet the pallets) and ruining those bales. If the bales are on edge, that problem will be eliminated. This is old school farmer info! Some folks will recommend that you throw lime powder on the bale stack as you build it (when storing the bales) as a means to deter the rodents. I have seen this done and have seen mice still making nests in the stack. The only difference is that now you have bales that blow lime powder all over the place whenever you touch them or move them. Not a good situation and not worth the (poor) results you will get from the action.

    Once the bales are in the walls, the density comes into play. Even if they were to get in, they would come out as soon as the plaster starts to be applies because they would see that they would be trapped. This happened in Australia on a build I did. The area had a MASSIVE mouse infestation (the whole shire due to the killing off of the foxes). The walls would fill with mice each night after we built. On the final night of the workshop, a guy sleeping inside the freshly plastered walls kept hearing a weird sound. He discovered that the mice were scratching their way OUT of the walls and running to freedom. After three days of this (yes, three days of mouse exodus…maybe five mice/day) it stopped. The owner has never had a problem since then. Keep in mind, this is in a shire with a major mouse infestation. The ground would literally shift like a blanket of mice when a flashlight was shone on it.

  5. Avatar
    Churchie Wed, January 29, 2014 at 1:59 pm #

    Hi Andrew just wondering how to secure the straw bales when putting them on top of one and other while building the wall ? Also do they have to B compressed and held down in some manner while building the wall up. ?
    Don’t know if this is two questions or one in the same ?
    Thank U Churchie
    Also I enjoy receiving your e mails and the subjects talked about 🙂

  6. Avatar
    Andrew Morrison Wed, January 29, 2014 at 6:21 pm #

    The bales should be stacked tightly against and around the frame. This will hold them in place during installation. If you plan to take more than 2-3 days to bale an area, then you will want to add squash blocks (horizontal pieces of 2×4 between posts) on top of bale courses to tighten them up. This is not necessary in most cases. It is usually required where the stack of bales is not in running bond, i.e. it is a stack of 7 bales piled on top of each other with nothing on either side.

    Once the bales are up, they will be held tightly in place by the frame itself. I recommend that people build their top bale stop (the flat framing that the bales are pressed tightly against at the top of the wall) to be 2-3″ lower than the bales are tall. Put another way:

    Height of the bales X number of courses + height of toe ups – 2 to 3 inches for compression. The answer to this equation is where you place the bottom of your bale stop to compress the wall during the construction.

    Thanks for your kind words!

  7. Avatar
    aeron Mon, October 29, 2018 at 1:31 pm #

    Aloha Andrew,

    My partner and I are building a load-bearing structure here in New Brunswick, Canada.

    We weren’t able to get any plaster on the walls this season so we’ve just wrapped the house in tyvek to close everything up as best as we could. Well, I’ve had to undo a bit of that house-wrap after having discovered a non-load-bearing wall of ours got pummelled by 80kmph winds and actually bowed most the wall inward. Inside I discovered some broken twine halfway up a balewall in a corner of our house. It’s troubling to me because that corner of ours has already been weakened by a previous mishap (foolishly failed to use corner guides + strong wind actually MOVED the entire roof over a few inches). What the hell should I do? Do the vermin matter much? Feel free to chime in on our other problems….

    Thanks for reading. And thanks muchly for your work. People have shared heaps of information with us during this, our stressful build.


  8. Andrew Morrison
    Andrew Morrison Wed, April 24, 2019 at 12:35 pm #

    Hi Aeron. Sorry for your challenges. That makes a stressful job (building) even more stressful. The roof issue can be handled by installing some type of connection point between the roof and the foundation. That can be strapping material, threaded rod, or cables. The key is that it needs to have a direct connection to the foundation and cannot simply sit atop the bales, even if anchored to the bales. I prefer to use Cordstrap and then once fully compressed, welded wire mesh on both sides of the wall. Be sure that the roof is in a plumb line from the foundation before you make your connections.

    For the wall bowing in, the welded wire mesh will help a LOT with that, especially once tied through with baling twine on 18″ centers both directions. Also, the compression of the wall with the threaded rod, cables, or strapping will tighten everything up. If you need to leave it for an even longer period of time without those supports, you may need to provide temporary bracing in the form of framing lumber and plywood. Hopefully you’ve been able to get past this stage of waiting and have secured the walls accordingly.

  9. Avatar
    Ronan O hEidhin Wed, July 1, 2020 at 7:12 am #

    As I’m building the rodents are cutting the baling twine. Do I need to take the wall down and start again or is it ok to leave the bales that are tight without twine and hope the plaster keeps them together?

  10. Andrew Morrison
    Andrew Morrison Mon, July 6, 2020 at 9:06 am #

    Hi Ronan. That seems like a pretty significant rodent issue. The most important thing will be to make sure that they don’t get in once the house is plastered. You should not be losing baling twine in the wall to rodents. It’s possible that the walls will be fine with the lost twine as the mesh and plaster will hold things together; however, that’s impossible for me to say with full confidence without seeing your project and the tightness of the bales. There are those who cut all the strings on the bales once the walls are built (I don’t agree with that approach, but some people still do it) and their walls don’t fall down. You will end up with a wall made up of loose straw straw though, so that makes repairs and remodeling harder, especially if you have water damage that requires the removal of a bale.

  11. Avatar
    Narayani Devidasi Mon, January 4, 2021 at 9:39 pm #

    Is a cement foundation the only option for straw bale builds in rural areas to avoid rodents entering from underneath?

  12. Andrew Morrison
    Andrew Morrison Fri, January 22, 2021 at 8:44 am #

    There are other options available; however, concrete is the best option when it comes to structural support for the house. Further, if code approval is required then you will likely have to use concrete in some form.

  13. Avatar
    Lisa Feldman Wed, March 31, 2021 at 2:56 pm #

    That is a straight up lie. Rats and mice love straw and other insects love to live in straw. Anyone with half a brain can figure that out go get a rat put some straw down there and find out what a nice house he likes to make with it.

  14. Andrew Morrison
    Andrew Morrison Wed, March 31, 2021 at 4:04 pm #

    Hi Lisa. You are clearly energized by this post; however, I don’t appreciate you calling me a liar. I think there is a different way to have this conversation and I’ll do my part with my response. To be clear, I don’t disagree with you that rodents do indeed like straw, but that is not the point of this discussion. A loose pile of straw is very different from a tightly packed wall, wrapped in welded wire mesh and other stucco backing, and coated in 1-1/2″ of lime plaster. A well constructed straw bale wall has been shown to be impenetrable to rodents, and even if they could get in, there would be nowhere for them to go because the bales are packed so tightly together. There are literally thousands of straw bale houses around the world that stand as testimony to this statement and blog post. There are lots of loose piles of straw that house rodents. There is a difference.

  15. Avatar
    Pascal Tue, November 9, 2021 at 8:30 am #

    Hi Andrew
    I have an existing 50 y.o. bungalow built with 4″ concrete block wall, 3″ gap, 4″ concrete block wall. Plastered inside and out with cement. Cheap and nasty wind blown fibre insulation was put into the 3″ vapour barrier about 13 years ago and after 8 years I had to get it removed because it was letting water across the vapour barrier.
    Is it possible to wrap this building in straw bales for insulation?

  16. Andrew Morrison
    Andrew Morrison Sat, November 13, 2021 at 4:40 pm #

    Hi Pascal. It is possible to use bales to wrap this building, for sure You will need to address the dead air space (where the insulation was installed) to make sure that it doesn’t create more problems for you and I would suggest a new ventilation gap between the bales and the block wall. Only a 1″ gap would be needed. I think the big issue you dealt with in the past (rotting insulation) was that there was a dew point created inside the wall system and that dew point dropped its moisture into the insulation. You can avoid this by adding the 1″ ventilation space between the block and bales and making sure that the bales are plastered well with lime plaster on the exterior face.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.