Rough Door Opening

Standard doors such as this [1] use a 38.25" opening for a 36" nominal door [2]. In the Seed Eco-Home, integrating production engineering into the equation we use the standard OBI 39" door opening (universal for doors and windows) for future modification/expansion possibility. We then add a 3/4" spacer as the doors require a 38.25" rough opening. This actually allows the 3 reinforcement spacer blocks on the side of the jack stud to remain as 1.5", so we use standard lumber instead of having to cut a spacer to size. This saves on build time. Extra cost of spacer is offset by ease of future modifications.