I was recently asked about using different finishes for straw bale walls on the interior. I’m very often asked about using different exterior finishes, but not as often does the topic of interior wall finish come up. Of course, the type, texture and color of plaster is always in question, but more rare is a discussion about using metal panels as a wall finish, or perhaps drywall or even tile.
The answer is that yes, these things can be done; however, “is the amount of extra labor worth it to you?” may be the appropriate question to ask yourself. Keep in mind that straw bale is an organic building material. Where this is most obvious is around curves by windows and doors. At every workshop I teach, people ask me about making a template to measure each window well with to make sure all of the window curves look the same throughout the house. Possible? Sure. Plausible? Not really. The fact of the matter is that each curve will be slightly different. That’s part of the beauty of building with straw bales. So now consider how you might finish an 18″ deep window well that has a natural, undulating curve to it, slightly different on each side of the window, while using metal panels. How do you attach them to the house? How do you adjust for the irregular shapes within the window well?
You can see where the difficulty comes in. The same is true for any material you use that is rigid and “unforgiving” to uneven sub straights. The key is to provide backing that fully supports the material in mind to ITS specifications. This means that you may have to insert framing to support the material every 24″ on center, or provide for nailing on a specific pattern. You’ll need to weigh the pros and cons of each finish you choose and see just what is worth your efforts.
I have seen corrugated metal roofing used in shower stalls and in straw bale barns to great success; however, would I do an entire room with that material? Probably not. I think for specific spaces that require something like this, it is worth it. If you want your walls to look like drywall on the inside, then I suggest you build with drywall, and forgo the straw bale infill, or at least create a hybrid installation system that will eliminate all of the “extra” framing to be notched in to the bales, post stacking.