In New Orleans the ground is half the job. A slab is only as steady as the soil under it and only as dry as the yard around it.
Do I need to worry about drainage?
Yes, more here than almost anywhere. Drainage is the first thing we plan. The city is flat, a large part of it is below sea level, and rain has to reach a street drain and be pumped out. Every square foot you pave sheds water faster than lawn did. A slab needs a slope of about one-eighth to one-quarter inch per foot toward the street, a yard drain or a planted area that can soak it up.
My patio slopes toward the house. How is that fixed?
A patio or driveway that slopes toward the house has to be corrected, because water at the foundation softens the soil and gets under raised houses. If the slab is sound, lifting the low side can restore the fall. If not, the panel near the house is replaced at the right grade. Where there is no room to slope away, a channel drain is cut in along the wall and piped to the street or a yard drain.
Can tree roots crack or lift concrete?
Yes. Tree roots lift and crack concrete all over this city, and live oaks do the most of it. Their roots spread wide and stay shallow because the water table is high, so they run right under walks and drives. As a root thickens it raises the panel above it. Crape myrtles, magnolias and water oaks do the same on a smaller scale.
Can I fix the concrete and keep the tree?
Usually you can keep the tree, and with a street tree you have to. Options that do not involve killing the tree include curving the walk away from the trunk, bridging over the root with a thicker reinforced panel, raising the grade with a ramped section, or using pavers that can be reset. Cutting big roots can kill or topple an oak. Trees between the sidewalk and the street belong to the city's Department of Parks and Parkways, so ask them before any root is cut.
My neighbor's new concrete sends runoff onto my property. What can I do?
Start by talking, and show them where the runoff goes in a rain. Often a small curb, a strip drain or a regraded edge solves it. Louisiana's Civil Code deals with natural drainage between neighboring lands, and in general an owner may not do work that makes the flow onto a neighbor heavier. If talking fails, ask the city's Department of Safety and Permits whether the paving meets zoning, and speak to a lawyer. This is general information, not legal advice.
Does clay or soft soil change the job?
It changes nearly everything. New Orleans has soft soil made of river clay, silt and old swamp peat, with water close to the surface, and it keeps settling for decades. On this ground we dig out the worst material, lay fabric where needed, build up a compacted base, use more steel and space the joints closer. Buildings go on piles. A slab on grade will still move a little over time, and a good design lets it move without breaking.
My gravel driveway turns to mud. Is concrete the answer?
A gravel driveway turns to mud because the stone is sinking into wet soil with nothing in between. Concrete solves it for good, on a proper base. A cheaper step is to scrape off the mud, lay geotextile fabric and add compacted crushed limestone. That same layer later serves as the base for a slab. Two concrete strips with grass between them are another option that keeps paving low.
My patio was poured over an old trench and it settled. Why?
It settled because the trench was filled in loose and never compacted. Soil dumped back over a new sewer, water or drain line keeps sinking for years, and the patio follows it down. This is common after plumbing repairs under New Orleans yards. If the slab is whole, the void can be filled and the slab lifted. For new work, a trench should be backfilled in thin compacted layers, and the slab reinforced where it crosses.
I am in a flood-prone area. Should the patio or slab be raised?
In a flood-prone area a slab is set as high as the lot allows without sending water to the neighbors. Concrete itself is not hurt by a short flood. Moving water does the harm when it washes soil from under the edges, so we thicken or turn down the edges and keep the base contained. If your lot is in a mapped flood zone, adding fill or building a slab for a structure can fall under floodplain rules, and the Department of Safety and Permits should be asked first.
Why does my driveway sit lower than my house?
Because the house is held up by piles or deep footings and the driveway is resting on the surface soil. As the ground sinks, the driveway goes with it and the house stays. You see a gap under the steps and a lip at the garage. This is normal in much of the city. A flexible joint at the house, and a short section that can be redone later, is the practical way to live with it.
Will permeable paving help?
It can. Permeable pavers, gravel strips or a planted band beside a drive let rain soak in on the lot and take load off the street drains. The front yard paving limit pushes in the same direction. Permeable surfaces need a deep stone base and some cleaning to keep working, and they suit patios and parking better than a main walkway.
The real number for your address comes from a free visit and a written quote. Call (504) 732-1542, or text a photo of the area and we will tell you what we see.