Help me add a pantry onto my kitchen

In My Humble Opinion
1

This may be a bit of a GQ question but there’s also a bunch of opinion involved so I’ll start it here.

I’ve got a smallish kitchen but a largish garage adjoining. I want to push a pantry into the garage to increase the kitchen storage.

Top-down diagram. (12K)

The main house is built on a separate foundation from the garage and we live in an area with expansive soils (Bentonite) so there has to be a bit of a consideration for very slight motion differences between the house & the garage. There’s two steps down between the kitchen floor & the garage floor.

Right now I want to build it like I was adding a deck onto my house. I want to attach a ledger board to the sill of the house (once I peel the garage wall off), extend 2x6 runners (probaby doubled) to 4x4 posts in the corners, add joists, then lay a plywood sheet on top.

Like this…(8K)

On top of that, I want to raise a rather standard wall with a top & bottom plates & studs of 2x4’s.

Some questions left unanswered, that you folks may be able to opine on…

  1. Should I (and how) attach the pantry floor to the back wall of the garage (see top pic link)?

  2. Should I make the back wall of the garage the pantry wall itself or build a new wall parallel & touching the garage wall? If I make the back wall of the garage the pantry wall, I will have to attach the floor of the pantry to the back wall somehow - can’t have the thing shift a somehow.

  3. Should I attache the 4x4 posts to the concrete garage floor or trust friction to keep them from moving too much.

  4. I’m going to have to use the garage’s trusses for the ceiling, the slightly lower garage ceiling would make a second ceiling too low.

  5. I intend to do the majority of the construction with long decking screws rather than nails. My poor nailing skills make a screw much more practicle. Anything wrong with this?

  6. How can I keep the tops of the walls from wiggling? (I think this leads me back to attaching this to the two garage walls again…

  7. Any tricks, besides careful measuring, for matching these two floors up?

  8. What else? I’m sure I’m forgetting something.

(Sorry for the link speeds, Comcast doesn’t seem to like outbound info)

2

IANAC (contractor) and IANABI (building inspector), but, as none of them has come along…

If the house and garage are on different foundations,
THEY ARE SEPARATE BUILDINGS!!!

If you proceed with your current plans, expect that the pantry will eventually:
a) collaspe from the 4x4’s rubbing on the garage floor (if you do not provide separate footers for them)
b) separate from the house (if you secure the 4x4’s to separate footers.

My WAG on best bet:

Pour a new foundation for the pantry by opening the house foundation and literally tying the rebars for the new foundation to the rebars of the house foundation, then building the pantry the same way any room addition would be built.

Failing that (say, if your foundation is block, brick, stone…):

Pour 4 corner post footers, secure the 4x4’s to the footers, and proceed with 2x8 or 2x10 joists, sub-flooring, walls, etc. and treat the pantry as a separate structure, using some kind of expansion joint between it and the house.

(and know that, whatever you do, you will probably void your HO’s insurance)

lesson: NEVER mess with the footprint of your house unless you’re ready to spend the money on architects, licensed contractors, building inspectors, etc.

3

Well as noted they are 2 buildings. Personally, I would make the pantry part of the garage. Make sure you seal things up well between the two (perfect entrance for pests) and let the pantry float against the house. Then adjust for movement with the stairs going down from the kitchen into the pantry. That way everything is tied to the foundation it is built on, and you aren’t twisting or shearing on anything.

But then I am in no way a structural engineer or contractor.

BTW you are not adding a new structure, just changing the floorplan of an existing one, I am pretty sure you don’t need all the permits and inspections, etc. I believe you are allowed to move/change non-structural interior walls in your own home with no worries.