Slab on Grade to Wood Joist Transition for Custom Home

[STrctPono]

I was going to transition the floor type on the bottom level from slab on grade to wood joists over a crawl space. The house is built on a very steeply graded lot and it just works out that this makes sense to me as this would save the homeowner on excavation work (existing ground is rock). I'm not sure if there are other issues I'm not considering. There is nothing I don't think I can work around but a few things off the top of my head...

1. The transition from slab-on-grade to floor joists will cut right through both the interior and exterior stud walls. Not sure if it is acceptable to just run the bottom 2x plate right across the joint.
2. The homeowners are using a floating wood floor so I don't think there will be any issues for having to joint the flooring at this transition location.
3. Anything else I am not considering?

I've always appreciated the help I've gotten here in the past regarding home design. Residential design is not my area of expertise, but every once in awhile I do end up helping out on a job.

 

[dik]

Just make sure that there is a connection of the sheathing to the concrete edge... either being supported on joists or a ledger and all concrete in contact with concrete shall be pressure treated.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KootK]

I don't know your local market preferences but here's one option to move the discussion forward. The floating floor does ameliorate some of the potential dimensional stability issues.

 

[IceNine]

I used KootK's detail once with 2x10s and there was significant shrinkage that caused issues with the VCT flooring. I recommend using some kind of engineered wood joists to lessen the shrinkage.

 

[dik]

At a discontinuity, your flooring should have a transition recognising the joint.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[r13]

Any potential for water to get to the joint?

 

[dik]

Inside... scrubbing floors, etc. a joint detail Use polyurethane caulk and maybe aluminum threshold strip... depends on flooring finishing.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[STrctPono]

Thanks KootK! See below for detail I was going to use that is similar but a little different to yours. The only difference is that there is no curb and the top of the finish concrete will be flush with the 3/4" plywood subfloor. I too was thinking the floating floor will solve a lot of the issues that I was worried about.

dik, do you really think the polyurethane is necessary. If water is leaking down that joint from above, I feel like the homeowners have bigger concerns than water coming through the joint itself. What do you think? However, you talking about that makes me think about termites and other bugs coming up through that joint. I'm probably overthinking it.

Do you guys see any issues with me running the bottom stud wall plate right across this joint? Should I joint the bottom plate too?

 

[dik]

If you expect significant water, then yes... else just a threshold type of 'cap' (like a carpet trim or VCT trim)... you have to provide some kind of joint cover. The architect should detail this...
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

Missed that... it's generally a good idea to have a joint at a point of transition.


Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik