The basics of the bench are:
Length: 9 feet (against the wall), 7 feet (against the work edge)
Width: 2 feet (24 inches)
Simply 2x4 framing, 4x4 supports and 3/4" in thick MDF as the surface
Also included was a pegboard wall measuring 8 feet wide for tool storage
As you'll see, I didn't follow my plan exactly. I didn't use diagonal braces and only used two legs. The fastening to the wall on the two sides provided more support than I thought. The workbench can easily support all the weight anyone could throw on it.
Step 1: Preparation of the installation space
The garage corner contained a central vac unit which limited the width of the bench, and I also wanted to "notch" the rightmost corner to prevent body contact when moving around the cars. Running into sharp corners is NOT fun.
1. Measured a level line at 30" above the garage slab lip. Since the garage floor is sloped, this lip gave a better starting place to measure from. The level line is marked in red.
2. I chalk lined the garage floor to get a good idea of the space I would be taking up and to see if the car would hit when pulled in.
Step 2: Framing
1. The first support frame 2x4 is laid against the level line on the 9 foot side on the drywall and secured using 2 1/2 wood screws into the studs of the garage wall.
2. The second support (along the short 2 foot side) is also secured along the level line using 2 1/2 wood screws.
Since I wanted the bench 9 foot against the wall and 7 against the front, I had to frame in the angled corner. There is a trick with getting the legs to create a level surface due to the sloping nature of the garage floor. It worked out in the end.
Step 3: Workbench Surface
With proper measuring, the surface material fit perfect.
I used 1 1/2 wood screw that were countersunk to achieve a flush finish
Step 4: Pegboard Installation
Since the surface was perfectly level, I lined up the pegboard along the surface to get an even look.