Installing baseboard just prior to the finish plaster application

Baseboard is an excellent idea to consider for a straw bale house. It’s not just pretty and decorative, but perhaps more important, it’s functional too. The bottom of the plastered wall is delicate, and a bit of trim protects it from the inevitable sweeping, mopping, or chair leg careening towards the wall.

A couple of days ago, I just got finished installing baseboard in our straw bale house. Having gone through that experience, I have some new ideas for how to install baseboard trim in the future. Here’s what I did this time, and what I’m thinking might work in future projects, too.

Installing Baseboard Trim in a Straw Bale House

The trick for installing baseboard in a straw bale house is figuring out what the material ties into. What is the attachment point where the wood can be fastened? My original thought and plan was to install 2×4 deadmen along the bottom of the wall, providing an attachment point every couple of feet. This proved to be ineffective, as the deadmen want to pull out of the wall as a screw is being driven in. It’s also very difficult to drive deadmen into the wall and have them stick out equal amounts. In hindsight, this was a very lame idea.

What I mostly ended up resorting to was screwing the baseboard into the wood floor at a downward angle, and into the posts at the edges. This is, I admit, not the most elegant option. The baseboard is very stable, but I felt somewhat unsatisfied with this approach. Firstly, I would have much preferred to nail into a surface (instead of screw), which was not possible. I used GRK FIN/Trim Head screws, which are quite discrete and very strong, but they’re also expensive, and sometimes difficult to remove. (They have a tiny tiny torx head.)

4″ wide oak basebaord affixed and ready for the next step

A better choice may have been to bump out the toe-up under the bale walls. Our house, like many straw bale homes before it, has a 2×4 toe-up installed under the wall. However, it is only as wide as the bales themselves, and once plaster is applied to the bales, it disappears under 1-2″ of mud.

In the future, I might consider attaching a 2×2 or 2×4 to the toe-up, before any plaster was applied, to use as a nailing surface for the baseboard once the base coat plaster was fully finished. Simple enough, I think, and I’m not sure why I didn’t consider it earlier. I suppose the trick is understanding how finish wall planes interact with each other — a bale wall is only at its final thickness once finish plaster is installed, and it’s important to know roughly what this thickness is in advance when considering other things like window trim and the baseboard itself. Ideally, and kind of finished wood trim should extend beyond the thickness of the wall — not too much, not too little. A little reveal is a nice, clean touch.

A Note on Making Your Own Baseboard

Equally important to how the baseboard gets affixed to the wall is what the baseboard looks like. I got this idea from a friend, but I think it can be modified as well. I made our trim from oak 1x boards, ripped to 4″ wide. The 4″ boards went over the table saw a second time, getting a bevel cut on the back side (the wall side), leaving about a 1/2″ or less “reveal” on the front. See the photo below.

The wall side of the trim has a simple bevel for “tucking” the plaster behind

The idea is that the finish coat of plaster tucks into the bevel, and if/when the plaster shrinks, there should be no visible seam from where it’s pulled away from the wood. Nifty, huh? The angle cut should be pretty steep to achieve this, perhaps even a bit more than what you see in the image above.  Another idea is to cut a rabbet into the back of the board, though that would be more difficult than cutting a simple bevel. Either way, this is an important detail if you want to achieve a clean interaction between plaster and baseboard. (You could use this same trick on any window and door trim, too.) I cut a subtle chamfer on the visible face of the trim with a block plane and called it complete.

Here’s what the finished trim and finished, plastered wall look like together.

The finished wall, with baseboard and finish clay plaster — note the reveal of trim beyond the wall plane