Homeadow Song Farm's Cob Radiant Floor -- the WorkParty

A couple of weeks later, Peter scheduled the Workshop Party.

Fall had already emerged with its brisk days, leaving the Indian Summer of our 1st visit behind. Although the workparty was planned for the whole day, complete with snacks and lunch, participants could choose AM or PM or both. When we arrived for the PM session, the crew was in full swing. The Window HQ (above) where we had worked before was now sheltered by a canopy and the gravel crew was loading buckets with gravel(right) to hand to the mixing folks through the windows. We headed beyond the gravel pile to the Music Studio doorway on the far side of the building.

The area just inside the door and under the stairs was apparently designated for tech tools and extra gear, and a couple folks were retrieving tools and surveying the work progress. Before entering the studio itself where the floor was taking shape with the help of a couple dozen focussed and energetic volunteers, we paused to observe the dirt pounding tactics.

The floor area was segmented into parallel lanes by lengths of 2x4 studs laid flat so that they concentrated the pounding forces to the lanes they defined. Several of the crew, on hands and knees, used blocks of wood to pound the dirt, creating the needed compression. The garden sprayer was kept handy just in case the mix needed a touch more water, but the cob was wanted quite dry compared to working with ordinary concrete. Plus a couple spare screeds. As the pounding crew made progress, they slid the studs toward new soil, ready to be compressed to hardness, delivered to cover the radiant coils on the floor behind them. Scooping the ready cob by hand, they filled the gaps left by the advancing lane dividers and resumed stomping and pounding the gap, just filled, level and hard.

To keep the new cob surface level,they had set a laser level in the doorway with its beam stretched across the room and one crewman went from place to place, momentarily setting up a special stud with a predetermined mark that had to match the laser beam's height when the stud had its foot on the floor's surface.

If the floor there was too high, so that the mark was above the lasers bright red streak, they summoned the crew member with the rake to scuff loose the excess cob, moving it to the waiting fresh area while pounding resumed to restore the rubbly to its former smoothness. The cob remains very compliant since cob takes a long time to cure, much longer than concrete, but errors in concrete are not as easy to fix.

If the floor at the place being measured was too low, they snagged more mix from the next wheelbarrow coming through, Each wheelbarrow's load that was dumped in a new area between those guiding studs was initially screed level in preparation for pounding.

Staying ahead of the cob workers, Randy and his small team were unrolling the last of the orange pex tubing so that workday participants got one last hands-on with the radiant floor components.

Shaping the coil of tubing to complete the layout, and anchoring the tube to the remesh at 1foot spacing, we connected it up with the manifolds located in the wall cavity behind where a bookcase with a removable back panel at the bottom will go. The coil, at least, was then ready for cobbing.

After neatly cutting the tubing to the needed length with a PVC-cutter, we tightened the fittings onto the brass hardware. Randy had already pressure tested the system. The controls for this system were a bit complex, especially because the studio owners wanted it integrated into earlier solar systems installed in other parts of the building, as well as being able to coordinate the zoning thermostats and safety valves. As a rule Randy makes liberal use of shut-off valves so that any puzzles and anomolies can be solved with no headaches. The PVC-cutter is the red-handled tool; the blue with the incredible jaws that required considerable strength to lock down tightened the rings that held the tubes tightly on the brass hardware. The yellow nylon ties stripped off the roll as needed. Note the tube's ends were kept taped til the last moment to keep the system's innards flowingly clean. The rest are pumps, thermostats and valves.

The fluid heated by the super-efficient boiler in the adjacent studio apartment would circulate through the tubing that entered the room above the doorway lintels and ran beneath coving to the bookcase wall, and would be routed to the insulated buffer tank that hid beneath the stairs-to-be, to be drawn on as needed without constantly having to fire up the boiler when one or another of the zone thermostats call for heat. The heat in the fluid running through the tubing in the floor would be effectively transferred to the cob because the cob was packed tightly around the pex. Before exploring the complexity at the boiler end, we crossed the mixing territory in the sunroom, which was adjacent to the last of the tubing to be covered. The sunroom whose windows served as portals for incoming buckets of gravel, and whose concrete floor served as storage space for the pile of sifted clay, was the staging area for mixing. Magazine articles on cob and radiant floors were posted around that area for spare moments. as crew members shifted from one operation to another so that everyone could try different things.

The outdoor crew shoveled gravel to a roughly measured level in each bucket before passing them through the windows to wait in the mixing area. Water, too, came through the window to wait in another bucket. (left) The buckets of clay were a little scant compared to gravel and were being filled from the indoor pile. Buckets for straw were filled only 1/4 full. (right)

When a barrow returned from delivering a load to the pounding area, crew members hefted 1 bucket of gravel 1 bucket of clay and 1 of the partial buckets of straw Beginning with the dry ingredients, some preferred mixing with a hoe, some by hand.

Once the dry mixing looked fairly thorough, 3 small scoops of water were gradually added to the process. When the batch was ready for stomping and pounding, it looked just barely damp.

Heading into the adjacent studio apartment we were greeted by the resident cat guardian. There was also a wonderfully affectionate huge dog, belonging to one of the farm residents, who wanted to help with that dirt work in the music studio, but graciously attended to the outdoor crew when requested to.

The original piping for the solar collectors on the roof of this area wound beneath the wood floor in the library and beneath the tiles in the kitchen. When the garden-sunroom with the green roof was added to the apartment, the solar system was extended in and hooked into a water-air heat exchanger. (left upper, with the bench-lid and cushion lifted) The air system, with its exchanger were built below the seating surrounding a pool with container gardening and sculpture. The heart of the complexity harboring both the new Q-boiler and the old solar HQ was in a closet by the kitchen pantry. The hand-drawn diagram posted on the new boiler's plain face was Randy's cheat sheet for users. (left middle) Amazingly, Randy had tied the labyriinth of pipes, valves, gages, and pumps, into one neat set of controls on the wall just outside the closet. (left bottom) The boiler and solar system in all its glory. (right)

Last but not least was clean-up time with the hoses outdoors. Between sessions and at lunch the barn opposite the studio provided picnic area indoors, with PVs for lighting and solar hot water. Peter and his bio-dynamic crew will tackle the linseed oil finishing when the cob has cured, which the radiant heat should accelerate and harden. Another day's fun. Today's was enough. Now would someone look after the cob oven, please.








Oy, some attention is needed for the cob oven!