The walls are board formed concrete walls. They are also structural walls. This is a very simple method wood forms are created. Rebar and fiberglass tie rods are used for added support and concrete is poured into the wood forms. Trainor Builders has done this for me in the 1880's Farmhouse as well. They did an amazing job. It is the same method used to form the structural bases of the Golden Gate Bridge concrete design. The concrete is compacted and vibration rods are used as well. The wood grain transfers onto the concrete. After 24/48 hours the forms are removed and voila! We are able use the wood multiple times.

Did your contractor mention issues with waterproofing where the board form meets the stucco or siding on the exterior? We love the board form look but our contractor is trying to steer us away from it.

I can't speak to you on what Trainor Builders did to eliminate/mitigate that concern. We have a first rate GC and this was our second project with them. Proper overhangs, flashing, caulking, and downright great construction has given us no problems. We used a matte sealer on the concrete for all 5 exterior concrete walls and only 3 of the interior walls. The kitchen backsplash wall, wine room storage as well as the shower. My advice is to inky have a GC or Sub GC do the work that has done it before. Ours looks AMAZING