Enlarging a room: Floor is poured concrete with different floor elevations.

Stats:
- House built in 1978
- 3br, 2bath single story ranch
- Poured concrete foundation

Goal:

- Convert a small laundry room into a home office, gut down to studs, reframe where needed.
- Laundry room is part of the garage space
- Expand room by 12" by pushing out interior wall, further into the garage space

Issues(possibly):

- The existing wall sits on a concrete block that is roughly 15" higher than the garage floor. The garage is poured concrete as well. And therein lies my conundrum. I just can't really wrap my head around how to handle this and take into account all the variables that may(not) come back to bite me 3yrs from now when the wall is sagging and the wainscoting is popping off because the garage floor slab sunk x inches (if that is even possible after 37yrs).

I was thinking that I put a top plate on the roof rafters, and a bottom plate on the garage concrete slab(after sealing the 12" of concrete the new wall will enclose). Then build out standard floor joists 16"oc mated to a 2x6 ledgerboard face mounted to the raised concrete block that is the current floor of the room.

...or...

Just hire a concrete guy to come and pour the addtional concrete needed to expand the existing floor out 12". I'm trying to keep the cost down though, hence the DIY effort.

I've scoured the internet, read all the vintage DIY book, the old school Rickels bible, but I just cant find anything that says how to properly deal with this.

Any advice is immensly appreciated!

Cheers

The wall between the garage and the house is considered an outside bearing wall in some cases so that woould have to be looked at before you start hacking it down.
The way you do this is build a wood floor platform first and build the wall on top of that, I would build the room 8Ft high with a ceiling, insulation and venting will be much easier that way and you can beef up the ceiling and use that for storage too.
If that is interesting to youy we can get into the how tos and pitfalls.

As I recall, you can't just build a wall directly on the slab in a garage. There needs to be a concrete curb of a certain height separating the garage from living space. Much like when you step down into it from inside the house.

beachguy005 said:

As I recall, you can't just build a wall directly on the slab in a garage. There needs to be a concrete curb of a certain height separating the garage from living space. Much like when you step down into it from inside the house.

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Ya, there are a few problems doing this, best is to come up with the esiest, draw the plans and submit for permit and see what they say. We get differnt answers from different citys. We have got away with building up walls off treated lumber plates and slip studs in the main walls to allow for any possible movement. But if it is not tied to the roof or any other structure above the slip studs are not needed.