A Review of Electrical Installations in Straw Bale Houses

Written by Andrew Morrison

modern straw bale house
Arkin Tilt Architects / Photo Ed Caldwell

If you are planning on building a straw bale home, chances are you will be including electrical services in the structure. Exactly how those services are installed is different in a straw bale home than it is in a conventional home. Knowing exactly how to install electrical service in your structure is important whether you plan to do the work yourself or hire it out to a subcontractor. You’ll either need the skills to install things properly yourself or in order to explain things to your contractor as they likely will not have worked on a straw bale house before.

It’s a lot easier to learn specific skills and building techniques in person with hands-on training, but I will do my best to describe the process to you here, step by step. Everyone loves bullet points, right?

  • Know where your service panel will be located. This is usually required to be shown on the construction drawings, but nonetheless is missed sometimes. It is important to know exactly where the panel will be located for two main reasons. First, if it is located in the bale walls, you will need to create bale stops on either side of the panel location so that the straw stops against a solid surface. This ensures the bales fit tightly in the wall and that you have free access to the box to run your wires in. Secondly, you need to know where to terminate your “home runs,” the wires that run from each circuit to the panel, so that you can power each location as necessary.
  • Create a game plan for your home runs. Because installing wires in the bale walls is harder than installing them in conventionally framed walls, it’s best to plan for as many home runs to be made through interior, framed partition walls. In this way, you can connect each load source (plug, switch, light, etc.) to a home run that returns to the panel as easily as possible. 
  • Bales Marked for Oven in straw bale wallMark you locations on the wall. I use a can of bright spray paint to mark all of my crucial locations on the bales before I start installing anything. This is a great way to locate potential problems before they arise in physical work. Be sure to mark out all of your niche locations before you start drawing electrical notes and runs on the wall. If you don’t, you may run electrical work right through the middle of a perfect (or at least what was a perfect) niche location.
  • Electrical Box Front View in straw bale wallBuild your mounting plates. I use a totally different system to attach my electrical boxes to the wall than most straw bale builders do. I used to use the “vampire spike” like other builders, but I have come up with a better way of doing it that creates a more solid connection to the wall. What’s even better is that the creation of the mounting plates is much safer than making spikes. The plates are made of 1/2″ plywood and should be a few inches wider on each side of the box than the electrical box itself. This usually means making 12″ x 14″ plates, or so. Cut a hole in the plate to allow the electrical box to fit snugly. Drill a hole in the upper corner big enough to allow your baling needle to fit through. You will eventually use this hole to temporarily tie the plate to the wall. Cover the plate with roofing felt and then insert the electrical box. You need to use “old work” or “remodel” boxes to work with this system.
  • Electrical Box Side View in straw bale wallCreate box locations on the wall. Turn the box so that the flat plate sits against the wall and spray paint its outline on the bales. You will need to use a chainsaw to cut a relief in the wall so that the plate sits flush with the plane of the wall. This means cutting just enough for the thickness of the 1/2″ plywood and then cutting a deeper hole in the bales to allow for the electrical box itself since it protrudes from the back of the plate significantly. Be sure to locate the actual electrical box at the required height. In fact, the temptation is always there to measure to and/or plumb and level to the plywood plate. Resist this temptation and make all of your measurements to the actual electrical box because that is all you will see once the plaster is in place.
  • Cut grooves in the bales. Use a chainsaw to cut grooves for the wire runs. I want my wires to be no closer to the surface of the wall than 2″. This makes sure that they will never be punctured by someone hanging a picture on the wall and it surpasses code requirements for wire depth in the wall. Always cut your lines vertically or horizontally. Do not cut corners by angling your wire runs. This causes confusion in the future and can lead to someone getting hurt down the line when remodeling or otherwise working on the electrical system, as most electricians expect runs to be installed in only those two directions.
  • running electrical wire in straw bale wallInstall your wires deep in the wall. Use a push stick to make sure the wires (direct burial wire/UF-B is acceptable for installation into the straw) are installed as deep in the wall as possible. Use 6″ – 9″ landscape pins to anchor the wires in place every 2′, at a minimum. It is important that the wires not migrate towards the surface of the wall overtime while you are completing later phases of the construction process. Once they are fully installed in the wall, stuff straw into the groove to completely cover the wires. This protects them from coming in contact with the plaster, which could destroy the casing. Leave at least 6″ of wire in the box to work with later.
  • Label your wires. It may seem obvious which wire is coming and going, but it won’t be once the plaster is in place. For this reason, use a permanent marker to label the end of each wire. Simple notes such as “HOT” and “TO LIGHT” are all you need in most cases. For more complicated installations, be sure to write as much information as you think you will need later to identify each wire. Tie your plates to the bales by using a bale needle to thread baling twine through the upper hole through the wall and back. This twine will be removed later, so just tie an overhand knot to keep things in place for now.
  • Electrical Plywood PlateUse the mesh to anchor your plates. When installing your mesh, do not attach it to the plates until you are ready to lock them into final position. Measure your box heights, and use a torpedo level to make sure your electrical boxes are exactly where you want them. Holding them in position, staple the mesh to the plates. Be careful to use staples that do not penetrate through the plate as that might pierce a wire. If you must use long staples, be very aware of where your wires are located so you don’t hit them. With the stapler in hand (and I’m talking about a pneumatic stapler that shoots structural staples, by the way)  attach a final plate cover made from plaster lath (diamond lath or blood lath are other names for this material). This gives the plaster something to hang onto over the plates and ensures a quality plaster job.
  • Hot Wire Locations in straw bale wallMark it up. Use your bright spray paint to outline where every electrical line is located in the wall before you plaster. Stand back and take some pictures to include in your home portfolio. This way, you will know where every wire is in the wall and you can make informed decisions should you decide to remodel later. Finally, place tape over the electrical box openings so that no plaster will find its way into the box and most importantly, into the screw holes.

Like I said, it’s easier to learn this process hands-on; however, I know that not everyone can make it to one of my seven-day workshops so I hope this was helpful in at least getting you started. Happy Baling!


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.

20 Responses

  1. Hi Andrew,

    Just read your newsletter on lighting. I’ve always found it helpfull, when giving workshops on lighting, to explain that natural light only travels through your windows and into your house for about 3.5 meters tops. With thicker walls the amount of light travelling in becomes shorter. Also with extended roofs, the amount of natural light coming in becomes even less.

    I’m sure you explain this in all the workshops you give, however not everyone can get to see you in person. So as you well know, good design is everything. Chris Keefe puts in a bay in the breakfastnook of the Applegate cottage, that’s excellent. Tall and narrow windows also work well I find with thick walls.

    Love your work, Constance

  2. This is a great point Constance. The use of natural light in design is very important and can be enhanced within straw bale construction because of the deep window wells. THe light bounces off of the curved wells and spreads across the room if built properly. This is a huge advantage of bale construction, yet again. Don’t build your window wells straight as they will end up cave-like. Instead, curve them or angle them to allow the light to dance across the room.

  3. Andrew,

    For my life I can’t understand this bit. It’s because electricity is the thing I know least about. I know none of the jargon and so I’m having a lot of trouble “seeing” this:

    “Create a game plan for your home runs. Because installing wires in the bale walls is harder than installing them in conventionally framed walls, it’s best to plan for as many home runs to be made through interior, framed partition walls. In this way, you can connect each load source (plug, switch, light, etc.) to a home run that returns to the panel as easily as possible.”

    This sounds like your saying, “drill holes in the posts and beams as necessary and draw the wire through them same as you would in a conventional home.

    Sorry, just cannot get my vision around this. Hope not to bother you with too many questions and your time is much appreciated.


  4. That’s exactly right, although the interior walls won’t be post and beam, they will be standard stick frame, stud construction. It is much faster and easier to pull wires through conventional frames so most of your runs back to the main box should be done this way. Consider that you may only need to drill though two studs and then go up to the ceiling. Going up requires no drilling, just some stapling, and then you drill through the top plate and run along or through the floor/ceiling joists. It’s fast and easy and ALL electricians know how to do this. That helps bring subcontractor costs down if you plan to use one.

  5. Hi Andrew,

    Although I took one of your 7-day workshops, it’s still terrific to have this short resource available as a reminder. Thanks!

    I think there’s a bit of confusion in my mind in the order of things in the 2nd to last paragraph? It’s clear from the picture that the plaster lath goes in behind the 2″ mesh, but I didn’t find it quite as clear from the text. I assume that the plaster lath doesn’t go on any sooner than this step as it’s fairly dangerous stuff to work with and you can easily cut yourself or nick one of your wires, correct?

  6. Hi Andrew,

    Sorry, another comment… When would an inspector have to inspect things? I don’t think they’ll trust me to have just done it all right behind the plaster.

    Cheers, Brian

  7. Hey Andrew,

    I am a big supporter of yours, thank you for spreading the knowledge and experience!

    I was wondering, if I am building a load bearing straw bale house, would this same method apply? We generally do not use chicken mesh or wire, and apply the plaster directly to the walls! Would making 2″ deep pathways for the wire in the wall jeopardize the strength of the wall, or possibly cause it to tilt? Is or is 2″ not that deep considering the bale width?

    Also, how can I 100% be certain that the wiring will not one day go faulty, heat up, and cause a serious problem for me?

    Unfortunately, since I am building the first straw bale building in my country (a developing country may I add), I need to get it right, and I;m not so sure how reliable the electricians here are!

    Sorry if I’m asking too much! 🙂 Looking forward to your reply!


  8. Hi Brain. Nice to hear from you and sorry about the confusion. You can put the lath under the 2″ mesh or over it. It really doesn’t matter. I usually put it on last (after the 2″ mesh) as I think that makes for a better base for the plaster since the 2×2 mesh holds the lath away from the plywood plate a bit and allows more plaster to key into the lath.

    In terms of the inspector, I call them out before we put the mesh on so they can see everything. Worst comes to worst, you can call them out after you have the mesh in place if you have total confidence in getting an okay, but there is certainly risk in that.

  9. I would suggest that you strongly consider using 2″x2″ welded wire mesh in your structure, especially in load bearing applications. It will make the building so much stronger and it will be that model of success you are hoping for. The mesh adds so much value to the overall structure by adding shear strength, out of plane strength (no need for pinning the bales with mesh), plaster reinforcement, ease in hanging cabinets and electrical work, overall wall stability, and so much more.

    If you don’t use the mesh, you will have to use the old electrical spikes for installation. They don’t work as well, but they do work. You have to either install the UF-B (direct burial) wire at least 2″ back into the bale, or use a conduit to install the wires into. Without one of those two options, the wires will come in contact with the plaster which is bad. The wires, if sized properly for the loads they carry, will not heat up and cause problems. If, however, you are unsure of the electrical work as it sounds you are, I would suggest using a conduit so that the wires are separate from the straw and could be replaced if need be. It’s more work, but if you don’t trust the electricians completely, it’s probably worth the extra effort.

  10. Thank you! I know I’m going to come across this information again in your book and construction DVD’s but, like you said, the more we see it the better. Oft and on I’ve thought about what I should do to remember where the electrical wires are AFTER the plaster is on the walls. Don’t know why I didn’t think about marking the wire runs and taking a picture for later. That is a super tip for me! Thanks!

  11. My wife and I are struggling with approvals and now budgeting to build a straw bale home in the San Francisco East Bay. There aren’t that many professionals (builders, plumbers, electricians) who are familiar with the building techniques where we are, and this has been a real challenge. This lack of competition seems to make everything more expensive than it should be. We are trying (in a climate perfectly suited to straw bale construction) to build an Eco-conscious alternative home and have been thwarted at almost every turn.

    As far as electrical, we were recently told by an electrician who was interested and excited by our project that he would not be able to take on the assignment because his liability insurance company would not take the risk due to perceived fire danger of sparks from electrical boxes in contact with loose straw.

    Could you speak to how real that danger is and how one navigates this issue to secure an electrician who is willing (and legally able) to take on the project?


  12. That is very frustrating Norman. Sorry you are having that experience. There is pretty much ZERO fire risk, above and beyond a normal installation. In fact, I would say the risk is far lower because of the overall fire resistance of straw bale wall assemblies. Their concern is strictly from a lack of knowledge. You can try showing them the ASTM test results that show SB walls to be far better than conventional in terms of fire resistance. You can let them know that there is no added risk as the electrical is contained within the boxes. You can let them know that the dense material in the walls does not allow for flame spread due to a lack of oxygen whereas the open stud spaces in conventional construction do, thus raising their fire risk.

    I suggest you contact the folks at CASBA (California Straw Builders Association) as they will be able to help you with California specific challenges.

    Wishing you success.

  13. Hi Andrew,

    I am wondering if the electrical box acts as a crack in the plaster.

    I was just starting to stack my bales but I stopped to take a good look a the electrical solutions I need to put in place. I live in Québec close to a lake in the forest so I get the hot, the cold, the humid and the dry conditions.(but mostly the humidity and cold) That’s why I don’t want to take any chances with the walls.


  14. Hi Mike. It depends on how you mount the electrical box. I would recommend a surface mount over a framed chase so you don’t actually have any bales behind it. It will make stacking easier and wiring MUCH easier. It will also allow you to provide a full seal behind the box so you don’t have to worry about moisture intrusion.

  15. Hi Andrew,

    My name is Santos, I from Nicaragua and I am student of civil engineer thereforeI would like to know what type of mesh do you use for protecting the electrical tube or electrical system?

  16. Hola Santos. We use either standard romex (sheathed wire), UFB (direct burial wire), or some type of conduit (either plastic or metal). The most common approach is to use standard romex directly in the bales. There are some articles on the website about it. Perhaps a search for “electrical” in the StrawBale.com sidebar will find you what you need.

  17. Hi Andrew,

    In the second-to-last picture, the box looks to be flush with the welded wire. How do you account for the thickness of the plaster? My assumption would be that the box needs to extend out slightly less than the thickness of the finished surface.

  18. Hi Rob. You are correct that it is flush. That’s actually what you want in this system. We use “mud rings” or “plaster rings” or “spark rings” (all pretty much the same thing) to adjust the box depth AFTER the plaster has been installed. This gives you much more flexibility to make things perfectly flush during the finish installation of electrical work.

Leave a Reply

Your email address will not be published. Required fields are marked *

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