Hey, first post here. Foundation question. Im in Florida, so no frost heaving. Site is sand mostly.
Looking for advice on slab v stemwall foundation for new project I’m planning.
Ground is pretty level where the house pad will be. Lowest corner is about 5″ lower than the highest corner.
Road sits 2’3″ higher than the lowest corner of the home site (about 50 feet from the front of the house, there is a drainage swale off the side of the road and a planned culvert for the driveway going across it. The front yard remains flat until it gets into the easement then slopes down toward the swale, and back up to the road.
I think I can do a monolithic slab here given how flat the site is. My thoughts are to cut out 4″ of existing soil and organics then place 16″ of structural fill and compact it. This will give me a 16″ deep footing to the virgin soil and allow me to backfill 8″ giving me 8″ between the finished floor and grade.
Conventional wisdom tells me to elevate the house above the road, but I’ve never built on a lot with a culvert and swale before so not sure if that mitigates anything.
Doing the stemwall of course adds expense and time to the build.
I’m attaching a sketch and pic of the site for reference.
Thanks
Replies
“In Florida”
Not sure where but,
Road height higher than the house?
Some would be thinking stilts.
Think through your design considerations, such as, but not limited to:
-elevation
-soil type and bearing capacity
-soil permeability
-site drainage
-structural requirements of proposed dwelling(s)
-long term maintenance
-budget
-special considerations
If you can't answer all these questions yourself, then chat with some engineers, design professionals, and/or other specialists. Spending some time and money in the design phase will pay dividends on the back end.
Good luck, and have fun!
@Nat_Elliston and the weather conditions: Rains can cause the soil to get saturated, leading to unstable conditions.
will you need flood insurance? consider how much repairs will cost if something goes wrong with culvert and drainage. stick with conventional wisdom.
You're in hurricane country. The more substantial your foundation, combined with how well you anchor the home to it, the better off you'll be when one passes over your home. In other words, go with a perimeter stem wall.
As far as elevation goes, I would situate the house AND driveway no lower than the road, and preferably about a foot higher.
Florida is not generally known to drain quickly after several inches of heavy rain. Better that your driveway and homesite be a dry peninsula extending from the road.
Thank you for the input. I got with the county site inspector and have a plan. It will be a 24” high monolithic slab. There will be a minimum of 6” between the finished floor and sod and minimum 6” fall in 10’ with a swale directing water to an outfall
Not a flood zone. Water drains from ground adequately. I feel comfortable being 1’ below the road. As are most other structures on that road