Building a Cob Cottage Step-by-Step
excerpted from Part II: Building the Cob Cottage
EVERY COB BUILDING IS UNIQUE, but most require the same basic steps. The order of some of these steps is critical; others can be rearranged as desired. For a first-time builder, it can be very useful to map out the sequence of all construction tasks. Following is a sample sequence to help you think through your project to completion before you begin. The next ten chapters walk through each of these steps in great detail.
* Select your building site very carefully, for best exposure to winter sun and for good drainage.
* Decide in advance roughly what spaces, shapes, and features you will need, both indoors and out, based on the scale of your own activities. Make many sketches and models. Keep the building as small as possible. If you need more than 400 square feet, consider phasing the project to complete the most essential sections first.
* Work on a scale model of the building, including site features such as trees and slope.
* Decide the wall plan in detail, especially where doors connect the indoors with outdoors. Design the roof at this point, including the roof and how it is supported. Make a full-sized mock-up of the building on the site. Spend time in it, and imagine what it would be like to live there.
* Assemble on-site all building materials you will need for enclosure, including glass, lumber, rocks, hardware, pipes, wires, and so forth. Gather your tools, scaffolding, and water storage.
* Check your soil, and assess by making test mixes and test blocks what needs to be added for the best cob mix. Measure your proportions and calculate the amounts of sand, clay soil, and straw you will need. Plan out and prepare mixing spaces close to the building.
* Arrange delivery of sand, clay soil, and straw as needed. Store deliveries close to and uphill from the building, in locations that won't impede work. Make sure straw is stored under cover, off the ground.
* Stake out your design and finished levels precisely on the site using many strong, firmly driven stakes. Adjust for the last time.
* Clear and level as little as possible. Grade away from the building so that water runs away on all sides. Set aside excavated soil for gardening or making cob.
* Dig drainage and foundation trenches, lay in drainpipe, insulation, plumbing, and wire connections; backfill trenches immediately with drain rock.
* Build the foundation stemwall, setting in door frames or frame anchors and joists if floor will be suspended. Leave openings for utilities and water lines in and out.
* Tamp the subfloor, lay several inches of drain rock, and, if you will be using an earthen or other mass floor, lay the floor base coat.
* Frame the roof, either on permanent posts or on temporary posts that will be removed when the walls are complete. You may also wait until the cob is nearly finished before framing the roof.
* Experiment with cob mixing techniques -- for speed, ease, enjoyment, and different numbers of workers. Concentrate on gradual improvements. Apply your mix, probably at first by fork, trodden, then using "Gaab cob" or cob loaves. Sew it all together solidly with your fingers or a "cobber's thumb." Try to raise all the cob walls at the same rate.
* Make sure you build vertical or tapered walls; don't leave big bulges or hollows.
* Pare each new part with a machete or handsaw before it gets too hard, leaving it ready to plaster as you build.
* Set pipes, wires, outlets, junction boxes, and so on into the walls as you build.
* Build in windows as you go. Bury "deadmen" in the walls, wooden anchors to which you can later attach door frames, shelving, countertops, and so on.
* Sculpt built-in furniture, bookshelves, niches, and alcoves.
* Let the walls dry and settle somewhat, then build loft or second-story beams, joists, and ledgers directly into the cob if the wall is loadbearing.
* Locate roof deadmen one and a half to two feet down from the rafters. Complete the walls.
* If the roof is on, you can now enclose and heat the building. If not, now is the time to build the roof. If the roof will be heavy, allow the cob to dry throughout first.
* Do final ceiling work.
* Finish interior built-in woodwork, counters, cabinets, interior door frames, and plumbing fixtures.
* Apply interior plaster.
* Lay a finish coat on floor. Seal an earthen floor with linseed oil and beeswax.
* When interior plaster is dry, apply natural paint, lime wash, or alis.
* Plaster the exterior, if desired.
* Have a big party! Invite everyone who helped you build.