A Goal without a Plan is Just a Wish
When our hand me down Costco playhouse collapsed in a winter storm of Jan 2016,
dreams of a natural building project swirled through my head. I immediately called friend, kindred spirit, jack of all trades, environmental activist and Wilmot WI resident, Pete Poli. Pete built a slipstraw treehouse in his yard “for his kids” and has been taken classes at a Natural Building School and is pretty much the man to call if you want to talk about anything sustainability oriented. We dived into natural building options, considering costs, materials available, labor and skill required. I decided on Cob, which is a mixture of clay, sand and straw that forms a strong, solid wall with the option to add artistic flair. I knew it would be labor intensive, which also means lots of opportunity for many volunteers to help!
We used an open design layout that could easily accommodate the coming and goings of numerous children vs. having a smaller door opening. Windows of different sizes for interest and imaginative play. A larger than normal roof overhang to protect from precipitation. Interior built in seating for relaxing on hot sunny days. A green living roof to showcase native plants thriving in harsh dry environments.
The green roof presented some construction design difficulties. All resources I found said you must make sure the structure is strong enough to support the loading of the green roof plus our snow fall, but no construction specifications were published. We wanted a lumber structure strong enough to support the green roof even without the incredibly strong cob walls. We consulted Lake County Building and Zoning for assistance in determining header size, joist size and spacing, and hardware. Although a permit wasn’t technically required, we did obtain one just to be safe.
We dig it!
No matter how strong we built the walls and the framing, lack of a good foundation could destroy all of our hard work! We wanted 4 foot concrete footings for all the corner posts, but figuring out how to also create a rock base under the walls took some head scratching. Our highway department shared a crew and excavator to dig the four foot deep perimeter.
Next we positioned the Sonotubes where the corner posts would go, and then backfilled with angular 3″ rock in the trenches and around the tubes.
With the rock supporting the sonotubes, we filled them with concrete and called it a day.
Raise the Roof
Wauconda resident and community service superstar Mark Knigge helped with framing. We used cedar 6×6 posts mounted into brackets on the footings. Headers are 2-2x10s stacked together and joists are 2x8s with 14″ spacing.
The best Bond Beam you’ll never see
To create a smooth surface to start our stem wall, we created a bond beam. The framing was done with 2x6s and leveled before adding concrete. It was beautiful. But hidden away forever, just doing its thing with no recognition.
It all Stems from There
The Stem-wall is a stone wall at the base of our cob structure. Its presence, along with a larger than normal roof overhang, is crucial to protect the cob walls from water. We chose Urbanite for the walls, which sounds fancy and expensive, I know. It just busted up concrete from sidewalks or patios. We found a local concrete guy who had a waste yard of concrete piles who allowed us to load our trailer up for free. I went back twice, since urbanite also became the material of choice for our patio around the walls.
We used mortar between the pieces of urbanite to create a solid wall. Lest you think you need experience, let it be known that garden volunteer Charlotte and I were mortar newbies. Fitting the pieces together is as addictive as Tetris was and also appeared in my dreams at night, just like the game. We were hooked! And if we currently lived in Ireland, you’d no doubt find us building endless walls.
Our stem-wall is about 18 inches tall and 10-12 inches wide, with the cob walls planned to be 13-15 inches wide including the lime plaster finish, which prevents water from finding a resting place on top of the stem-wall.
So hey, when you have free patio material, you build a patio! Occasionally I used a sledge hammer to break the pieces to get a more desirable shape, but most of the time, I was picking and choosing, rotating, and leveling..
And with that, we are ready to begin Phase 2–Messy feet and Happy Hearts–Building with Cob