Thread: Kitchen addition built on 4 inch slab ... OK?

Hi,

We are considering purchasing a house in our home town, Sarasota, Florida. The previous owner built a kitchen on the back porch which measures 12 x 15. The 4 inch slab was lower than the rest of the house. They ran 2x4 boards, side up, the put 1 inch boards on top. The wood floor feels sturdy. It is the 4 inch slab I am concerned about. This is a common practice in Florida ... not to say it is a correct practice. I have not been able to get a definitive questions from contractors or inspectors as to weather or not I will have problems in the future. We estimate the addition is about 10 years old. We have not been able to identify any cracks on the walls or ceiling that would reflect foundation or settling problems.I am interesting in hearing opinions and experiences. Suggestions how to "shore it up" would be appreciated. I have read about "slab-jacking" ... can this process be used as a preventive measure by providing additional support or is it only used as a corrective measure.

Thank you,
Ned

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Originally Posted by Ned Bowman

Hi,

We are considering purchasing a house in our home town, Sarasota, Florida. The previous owner built a kitchen on the back porch which measures 12 x 15. The 4 inch slab was lower than the rest of the house. They ran 2x4 boards, side up, the put 1 inch boards on top. The wood floor feels sturdy. It is the 4 inch slab I am concerned about. This is a common practice in Florida ... not to say it is a correct practice. I have not been able to get a definitive questions from contractors or inspectors as to weather or not I will have problems in the future. We estimate the addition is about 10 years old. We have not been able to identify any cracks on the walls or ceiling that would reflect foundation or settling problems.I am interesting in hearing opinions and experiences. Suggestions how to "shore it up" would be appreciated. I have read about "slab-jacking" ... can this process be used as a preventive measure by providing additional support or is it only used as a corrective measure.

Thank you,
Ned

1. You shouldn't have to guess. Due dillegance - and some time. Go to the Building Department and FOIA the records, plans, permits. While you're at the building department inquire as to which codes/versions were in effect at the time the work was done. Then ask where the respository is and do your research as to what the "standards" were and referenced on the plans and permits. Rrequest copies of all the code enforcement inspections, citations, history of the property,etc.

2. You can also research court actions, enforcement issues, liens, etc. Again all public records.

3. mapping and arial photograph services you can pay for prior year's fly-over photographs.

4. Go to the library or repository and do the reading.

If you're still interested in proceeding,

Hire a professional Home Inspector to do a Home Inspection.

At first, it sounded like you were describing a summer, or outdoor kitchen. Wet bar, gas grill, maybe a small fridge. (Quite common around here.)

Then you mentioned sleepers for floor structure and support, walls and ceilings, etc., so it now sounds like an interior addition to the living space.

Without more details, I’d guess it’s an non-permitted addition. The original exterior porch or patio slab likely lacks the required footing for this type of use. There are probably other key building and safety details that were ignored or left out.

Basically, it sounds wrong. Repair options will likely be band-aids. Pressure grouting (slab-jacking, or mud-jacking) is typically used to correct problems with a properly constructed foundation. While they can inject grout under a slab to support almost anything, it sounds like throwing good money after bad.

Call a local inspector and proceed carefully.

Dom.

To start, I have no idea what concrete requirements or soil conditions are like in FL so I'll look at this from a construction viewpoint. 10 years old and you don't see any problems, then maybe its fine. If it was going to move then it would probably have done so by now. If the guy tamped the ground really well, and put in a good subbase then the 4" could be fine.
Normally, 4" of concrete would not be sufficient for occupancy space. I don't know what your foundation requirements are either in FL. The problem I see here is that the structure is subject to potential higher changes based on very common conditions. You remodel the kitchen and put in much heavier appliances and cabinets; you don't pay attention to the downspout and it washes out the dirt at one corner, grading gets changed and affects the slab, etc. With a more suitable slab and footing set-up these wouldn't be issues at all or only minor issues. In your case they could become major issues.
Have you determined where the kitchen drain goes?

If your concern is the 4" slab, then nothing to worry about as the typical slab on grade slab is 4" thick.

Of course, though, what there may be to worry about is that if you can measure the 4" slab thickness, then there is no thickened edge footing around the perimeter of that slab and the wall and roof load could crack off the edges of the slab.

If you can measure the 4" thickness of the slab, I suspect that there was a 4" thick patio back there and the previous owner simply constructed the kitchen addition on top of it, by the way, that concrete patio slab would like have been down 4" ... right where you said it is ... that is not a good sign.

My guess is that the kitchen addition is unpermitted and not structurally safe (i.e., no footing under and around the perimeter as is required).

Call the local building department, better yet, go by there, and ask to see the permits for the house. That could be a tear-it-down-and-rebuild-it kitchen remodeling job you are looking at being responsible for if you do not check it out before you buy.

The 2x4 sleeper system with 1x floor decking is not a problem with regard to being structurally sound (as long as the spacing of the sleepers is not too great, if the sleepers were too far apart the floor would feel like a trampoline, if it is good and solid feeling then the sleepers are likely spaced properly - except that I dislike using the term "properly" with any unpermitted work) as it is resting on the concrete slab - it is the concrete slab which is the potential structural problem.