Converting wood-house foundation beams to flat beams

Lately, to accommodate under-floor AC units and duct routing, we increasingly want to reduce the foundation's upstand. The conventional move is to use an inverted (upward) beam, keeping the foundation beam continuous.

But that pushes up construction cost, and complicates the constructability if you're insulating under the bottom slab. Honestly, most people would rather not use inverted beams.

In our office, when no special extra strength is required, we use flat beams. We provide upstands only at the minimum necessary spots — where anchors land and the sill plate sits. With that, you don't need opening reinforcement or inverted beams, and you get a clean foundation form.