In order to support point loads from our timber frame posts, the outside edge of our cottage's concrete foundation will be roughly 12" deep, while the central portion will slope up to 6". To create this shape, we filled most of the form with 3/4" stone. Then, we spent hours raking until it was perfectly level, as measured by pulling multiple strings across the top of the form.
Once that laborious task was complete, we proceeded to add reinforcements for the concrete. First, we screwed eyebolts into the form, piercing the vertical insulation along the sides. Once the concrete is poured and dry, the bolts, and in turn the form, will be locked to the slab (we're leaving the wood form in place to hold the vertical insulation against the slab).
As an added bonus, the eyelets can hold reinforcing rods in the center of the thickened edge of the slab! With a little instruction from Rick, we cut rebar to length, threaded it through the eyelets, and Tara tied them together with wire ties.
Next, we laid 4'x8' sheets of 6"x6" wire mesh over the entire interior of the form. In addition to strengthening the concrete slab, the mesh makes a convenient substrate for our radiant heat tubing, which will be laying in runs 6" on center. Once the wire mesh was placed, Tara tied the reinforcements together using wire ties.
Next up, installing our radiant heat tubing, and bracing the form for the concrete pour!