Doors and Windows - Unusual French Door Install

I'm installing an outswing french door in a window opening. This is on slab/stucco exterior construction. The framing is flush with the edge of the slab but then there is one inch of styro insulation plus about 1/4 inch of stucco. To mount my door frame flush with exterior stucco would mean having the door's threshold overhang the slab by about 1 1/4 inches. This unsupported overhang is a problem to me.

My thought is to put down treated 2x6 on the subfloor, cut to the width of the door's threshold. This of course would raise the install by 1 1/2 inches, but with 5/8" wood flooring and 3/4" quarteround against the interior of this "boost" it would be covered.

I want to mount flush to the exterior so the doors can swing wide.

Any thoughts?

LG

If you use the method you suggest, a 5/4 x 6 treated deck plank would also work, and lower your door by 3/8". You could also remove the subfloor to lower it even farther- just be sure you get a nice tight fit and use construction adhesive. Instead of making it as wide as your rough opening, make the rounded front edge as wide as your brickmould-brickmould, then notch out the sides for your rough opening.

The problem with stucco installs is flashing the perimeter- and in this case, the bottom.

I take it you already have the door, if not order a bigger jam, standard is 4 9/16, you can goto a 5/916. If you have the clearance, you can use a 1x6 instead of the 2x6.With the unit sitting even with inside of the house is how you want to sit the unit.You can support overhang with a ripped down 2x4 under it.

Or you could use a concrete patching mix to build up the slab to meet the underside of the threshhold. I've had good results with the fiber mesh reinforced products. Be sure to clean the existing surface well and use a bonding agent.