Hardwood floors in a straw bale house may not be the most common of floors, but they sure are beautiful. The reason they are not the most common is that most people want to couple the thermal mass values of concrete or earthen slab floors with the thermal insulation values of the bale wall assemblies. This makes sense, but is not always applicable. For example, some homes are built on raised floor foundations and as such, are better suited for lightweight floors like hardwood or engineered wood floors. Some owners simply prefer the look of wood over slab products, while others find that their physical and/or financial limitations require them to work with wood floors over slab materials.
No matter what your reason for choosing hardwood or engineered wood floors, you will run into an issue that folks who build with slab floors won’t have: edge gaps. It is absolutely essential to leave a gap at the edges of your floor where it meets the wall. If you don’t, your floor will buckle over time as the floor expands and contracts. For this reason, the edge gap is also known as an expansion gap. For floating floors, it is also required to allow the floor to move as needed to avoid buckling. Be sure to check with the manufacturer specifications for your floor material before you start installation. In fact, I suggest you check those specifications before you start your baling process.
When you have a gap at every transition to every wall, it doesn’t look very good. For this reason, you have to find a way to hide the gap without ruining its purpose. I have three methods that work well yet each has their challenges. The first option is the standard application of baseboard trim. This is the obvious answer because it is what has been done in construction for many years. Most people don’t realize that the baseboard trim they see in structures is not there just for looks. It hides the gaps! This works with straw bale walls too; however, there are caveats.
First, the baseboard is attached to the framing in a conventional wall system; however, if not planned for in advance, the framing in a bale wall system is behind an inch or more of plaster. This is okay, but there is a better way. After the bales are installed and meshed and you are ready for plaster, add an additional skirt board on the face of the toe ups that will become your nailer. You can finish the plaster to this board as a straight edge and then nail directly to it when installing trim. Be sure to use a board that is shorter than your trim. For example, if you plan to use 3″ baseboard, then use a 2″ skirt nailer.
The second issue, and one that is harder to address, is the curves at doors. Because the curves are created with the stretching of mesh over the straw and are organic in form, there is no great way to attach straight, rigid wood to them. First of all, you will need to bend the material either by steaming it, back kerfing it (cutting relief cuts in the back of the trim), or by using flexible/engineered wood products. Secondly, you will need to find a way to attach the material. In some cases, cross nailing into the plaster while also using adhesive on the back of the trim is sufficient. In other cases, providing a nailer, like above, is required and that takes some pre planning of its own.
A second option is to use tile. Although completely rigid, it is smaller in length and can thus be installed even on uneven surfaces. If you install it to the scratch coat or brown coat, you can use the remaining plaster to make up irregularities. Exactly how many irregularities you have will determine which application time (scratch or brown) is a better idea. I personally prefer to attach them after the brown coat. Because of the “flexibility” of a tile job, you don;t have to provide backing and the curves at doors are not an issue.
The third option is to use J channel in your plastering to hold the plaster up off of the ground, thereby leaving a gap for the flooring to slide under. This can be challenging during floor installation as you need to leave enough space to insert your floor tool (that tool which pulls the last piece of flooring tight into the previous pieces). When complete, it looks really sharp! It basically leaves you with a shadow line at the floor to wall transition which is a great look in my opinion. Similar challenges exists in terms of attaching the J channel to the framing, especially at the door curves. As before, it is all doable and I believe the end result is well worth it. I’m a fan of clean lines and simple design. This is it for me when it comes to transitioning a wood floor to a plaster wall.
Have another way that you have had success with? Please leave us a comment below so we all can learn!