In May of last year I began renovating a small “craftsman” style home in Southeast Portland. I planned to add a bathroom, bedroom, and remodel the kitchen. I gave myself 6 months to complete the job…
9 months later, I am finally putting the finishing touches on the project. The old expression that building anything always takes longer and costs more than you think it will proved to be true, even for someone who often tells people that their project will take longer and cost more than they think!
Part of my intention for the project was to incorporate some natural building techniques into what is otherwise an ordinary, conventional home. I did not want to build new cob walls or insulate with bales: these things would have been challenging not only with the space I had available, but also to get past the code officials (I did everything with permits). But earthen finishes, such as plasters, paints and floors, require no permitting and are easy to retro-fit into existing spaces; so I decided I would do as much of that as I could.
For parts of the downstairs, I applied a custom-made earthen plaster over new and existing drywall, and for a remodeled bedroom I mixed and applied a simple clay paint. Both turned out beautifully. I chose not to go over the walls of rooms that were mostly intact- there seemed little reason to go over perfectly good, existing paint.
I got to try some more interesting stuff upstairs, where I didn’t have pre-existing walls. Instead of putting drywall up over my new walls there, I decided to try to mimic the traditional plaster-and-lath technique that you find in the older houses here. Traditionally, strips of wood lath ¼ inch thick and 1 inch wide were nailed up over the studs about ¼ apart. Next, a layer of lime plaster (made of lime, sand, and horse hair) was used to cover up the lath. This coat was followed by two or three additional coats, which further strengthened and smoothed the wall.
For my walls I didn’t want to use lime- not only does lime have high-embodied energy, it’s also caustic and harder to work with- so I did the same procedure but with an earthen plaster made of clay, sand, and chopped straw. I followed this rough coat with another “scratch” or second coat, and then finally a finish coat of very thin plaster with color. The results are beautiful, and the walls feel as stable and solid as drywall.
I recommend this technique for anyone who is drawn to the idea of having natural earthen walls for aesthetic or idealogical reasons, but not because they think it will be easier or cost less. Drywall goes up very quickly (especially if you hire a crew) and is very inexpensive due to mass production. But it is also an environmentally destructive product that requires significant mining, manufacturing and transportation operations. And when it is time to remodel or tear the house down, it all goes to a landfill. My walls, should I ever choose to tear them down, could literally be spread in the front yard or in my garden.
Another interesting thing I tried on my house was a small section of exterior earthen plaster. I applied 2 coats of plaster over reed mats that were stapled to the siding. The plaster contained no cement or artificial sealers. It did have some flour paste in it to help minimize erosion. The areas I chose to plaster are fairly well protected from the rain, but after a Portland winter have gotten wet plenty of times and still look great. I am considering finishing my whole house this way when it comes time to redo the siding or paint…
The last “earthen experiment” I tried was to put in an earthen floor in an upstairs bedroom. I’ve done earthen floors over ply-wood before, but never on the second floor of an older house. Weight of the earth and movement of the sub-floor where both concerns, so I poured a very thin floor (1/2” thick) and imbedded burlap netting in the mix to add tensile strength. So far it looks beautiful and only has a few hairline cracks.
After my experience integrating these earthen techniques into my house I am convinced that there are many applications for natural building in conventionally built homes. But it’s not for everyone: these techniques are not widely known, and if you are concerned about resale value, or don’t want to do maintenance yourself, it may not be a good choice for you. There is no evidence to show that earthen finishes would in anyway reduce the value of your home, but they are just not materials that are widely known and understood, which might reduce the number of potential buyers. But unless you plan to sell your home very soon, I think you would be much better off creating a place that YOU love, rather than worrying about what some future owner will or won’t want. The only thing stopping you from integrating natural building materials into your home is the willingness and the time to try it!