I'm working on a similar project - putting a gas fireplace in our living room (gable wall) with the floor about 5' above the ground. I've done some research but haven't found much yet.

Here are some photos I saved showing a wall framed and ready to accept a shop made bump out.

If I find out more, I'll share it here. Please do the same as I'll be checking back. I hate the idea of paying an architect for such a simple project.

Not sure if the OP is still following this or if I'm just talking to myself.

We had some friends over last night, one of whom is a GC.

I was telling him about my project and he said that the rule of thumb for cantilever is that you have to go back 6' into the house for each 2' of cantilever.

As mine is going on a gable wall perpendicular to the floor joists, I'll need to support the bump out with either a full block foundation tied into the existing footings or two piers.

This project just got more complex than I thought it was going to be.

Ha!

I found the solution:

From: Graphic Guide to Frame Construction: Walls, by Rob Thallon, architect and Associate Professor of Architecture at the University of Oregon.