How complicated and costly is it to do a bump out from a kitchen for a space that extends between 2 and 3 feet outward and about 6 to 8 feet wide?
Is there a certain size below which less structural supports and work is needed and does that vary from area to area?
Bumpouts Are Additions
Bumpout, add-on, micro-addition: whatever you call it, it is still a type of addition.
True, it's not 1,200 feet and two stories of living space, bathroom, and HVAC. But it still shares much of the same properties as a full-blown addition.
But first the good news: given the reduced dimensions of a bumpout, it will still be exponentially less expensive to build a bumpout vs. a full addition.
How It Is Done
Whenever you remove a load bearing wall--and all exterior walls are load bearing--you need to duplicate its function in another way. One typical alternative is to replace the wall with a LVL, or laminated veneer lumber, beam.
The 6-8 foot width is especially encouraging. When you get into these very long spans (say, the entire width of a kitchen) that becomes a major and expensive undertaking.
Because the new space is so small, you will probably not have to add extra heating or cooling capacity.
Still, it's like a mini-house you're building--foundation footings, siding, electrical, shingles, perhaps a window--so that drives up the cost, too.
Bumpouts are oddities that do not often get built, so pricing is difficult to determine. Homeowners who have done similarly sized projects report that they cost between $5,000 and $15,000.