One of the neat things about cob is that it can be used to sculpt many interior features of a house. Cob bookshelves, niches, and benches all add to the beauty and personality of the house.
Any wooden shelves, shelf supports, counter tops, or wood to support cupboards can be embedded into the cob as you build. It’s much easier to sculpt cob around wood than to cut the wood later to the organic shape of the dry cob. Everything that you build in as you go will save you a lot of fussy wood cuts later. Just make sure you cover the visible parts of the wood as the clay may stain the wood.
Niches are excellent spaces to built into walls to create an altar, bookcase or a place for candles. These are fun to sculpt in as you build. If you finish a wall and then wish you had built a niche, you can carve one out later. This is much easier to do if the cob is still wet. When building with Straw-bale or Light Straw Clay you can carve them out before applying your plaster.
The tops of the niches can be treated like any other opening. They will need a lintel or an arch. If you make niches less than a foot (approx. 30 cm) wide, you can forget about the lintel or arch rule and let your imagination go. But just remember, the thinner walls in the back of the niche will be less insulating than the thicker parts of the wall. If you live where it’s really cold, you may decide to forget the niche idea. A solution might be books, as they are reasonably good at insulation so you could make a bookcase niche and keep the shelves close together and full.