In American English a slab is a partially rounded "first cut" of a log. In Australian English a slab is a thick plank. Could you clarify the meaning, this is an international forum.
There is such a thing as wood foundations, but modern times the wood is pressure treated to be rot resistant. Generally I do not think of wood as being a good choice for earth sheltered buildings unless they are simple and non-durable. The "first cut" slabs are also mostly sapwood which generally rots much faster than heartwood. Are you thinking of a durable building?
posted 5 years ago
First cut of wood - rounded log-sides. Might not need to be a long-term structure - maybe last 15 years or so. I would make the floor out of rammed earth and the walls/roof out of slab. It's Tamarack (larch) which is a very rot-resistant wood.
No plans just winged it. Dug a hole about 6X6X6, 4 aspen poles in 4 corners that went from the bottom of the hole to the roof height. Horizontal logs forming the underground box. The 4 aspen poles hold them against the dirt, no fasteners. Slabs on three sides above ground, overlapping each row a little to keep water out. Recycled decking from a neighbor for the door and front wall. Recycled fiberglass for the see through roof, adds light. Recycled 3/4 inch plywood interior and seat hole. Recycled seat. False wall behind seat that lets air circulate from pit to top of roof, outside. Screen at the top triangle openings to keep bugs out. Everything above ground was nailed together.