I have a rotten sill plate and sheathing on the gable end wall of a one story ranch. There is a short 4 foot high wall on top of the foundation wall supproting the first floor. It is 2X4 construction with 1/2" OSB sheathing and vinyl siding. The sill is rotted due to almost no clearance between grade and the top of the poured concrete foundation wall.

Two questions - First, can I install a single course of block on top of the foundation wall to increase the distance from grade to the framing and if so, how long should the mortar cure before building the framing? How about on the adjacent load bearing wall?

Second question - I can easily support the load bearing wall by framing a temporary wall after taking off the tension with support columns. How do I support the gable end wall that runs parallel to the floor joists?