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Key West Concrete Company
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Slab foundation building in Key West FL - a base that fits your flood zone

Planning a new building or replacing a cracked, sinking slab? Get a reinforced base planned for your lot, your flood zone and the salt air.

A slab foundation is the reinforced concrete base a building sits on, and what makes it last is hidden under and inside it. We pack the base, set the steel and check the layout before the truck comes, since none of it can be fixed later.

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Stamped concrete patio with a circular stone fire pit and block retaining wall beside a brick garage.
  • Fully licensed and insured.
  • Free estimates at your property.
  • We reply within 1 business day.

A slab built for island ground

  • I come out myself

    I measure the lot myself, and our form setters and finishers do the work with me.

  • Fully licensed and insured

    The city requires specialty contractors to carry a competency card for their trade, and we're fully licensed and insured.

Is a slab foundation right for my Key West lot?

Slab foundation building in Key West means pouring a reinforced concrete base, with steel set inside it, that carries the weight of the building above. Whether a slab suits your lot starts with your flood zone, because the zone can rule out a building resting on fill, so that's the first thing we look up with you. The price moves with the size of the slab, how much digging out and packing the ground needs, how much steel goes in and what the design does to keep salt off that steel. The schedule turns mostly on the permit, any historic review and the weather on pour day, and we handle the permit paperwork with the city's Building Department when a job calls for one. I measure the lot on site, and your written scope and price come from those numbers.

Slab foundation options in Key West

  • Slab on a packed base

    This slab is poured on subgrade, the ground under the slab, which we dig out and pack so it doesn't settle later. On A Zone lots the building codes cover how that fill is placed and compacted. The base is the last thing I'd cut from a budget, because nobody sees it after pour day.

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  • Slab with thickened edges

    The edges are dug deeper and poured in one piece with the floor, so the footing and the slab go in together. It suits garages, sheds and smaller buildings on firm ground where the flood zone allows a slab on grade.

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  • Slab for an addition

    When you're adding a room, the new slab has to meet the old floor at the right height and tie into the existing foundation. We check the old slab's level and condition first, so the two don't settle apart.

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  • Larger slabs for shops and storage

    Commercial and storage buildings usually carry heavier loads, so the slab gets thicker and holds more steel. If the property needs paving too, we plan it with concrete parking lot building so the grades and drainage line up.

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What signs tell you a slab needs replacing?

  • Rust stains on the concrete

    Brown streaks, or chips that show bare steel, usually mean salt has reached the reinforcement, and rusting steel swells and breaks the concrete around it.

  • Cracks that keep growing

    A hairline crack is normal, but a crack that widens, or one side sitting higher than the other, points to ground moving under the slab.

  • Floors that slope or sink

    Doors that stick, tile that pops loose or a floor you can feel running downhill usually mean the base underneath has settled.

  • Water standing by the walls

    Puddles that sit against the house after rain mean the ground falls the wrong way, and that water works its way under the slab over time.

How a slab foundation job runs, start to finish

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  1. You call or send the form

    • Call (645) 300-7417 or send the form
    • Give me the property address
    • Tell me what you plan to build
    • Ask anything you want answered first

  2. I visit and measure

    • I look over the lot myself
    • I ask how you'll use the building
    • You get a written scope and price
    • We handle permits and any historic review

  3. We build the slab

    • I check the base before the truck
    • Forms, steel and layout checked again
    • Our crew pours and finishes the slab
    • Control joints cut so cracks go where planned

  4. Cleanup and walk-through

    • We clean up the site
    • We walk the finished slab with you
    • You see the edges and joints up close
    • Your questions answered before we leave

Ask for a free slab foundation estimate

Put in the property address, its flood zone and whether it sits in the Historic District. We reply within one business day, and the on-site estimate is free with no obligation.

Slab foundation questions we hear

Here are the answers to what Key West owners ask most before a slab goes in. If yours isn't here, call and ask.

How do I find the flood zone for my property in Key West?

Start with FEMA's flood map tools, which show your property's official flood hazard determination. Where an effective map exists, it sets the minimum flood rules your slab has to meet. If FEMA's proposed maps take effect, a number of Key West buildings now in X zones will move into AE zones, so we look at both with you.

Can a building sit on fill in a V Zone in Key West?

No. In V Zones, FEMA's rules don't allow fill to support a building, and pile or column foundations have to be used instead. If your lot is in a V Zone, the plan starts there, and our foundation installation page covers that side of the work.

Do I need a permit for a slab foundation in Key West?

Almost certainly. The city requires a building permit for work over $1,000 in materials and labor and for any structural change regardless of cost, and it advises calling the Building Department at 305-809-3956 before grading, filling or building. We handle that paperwork when the job calls for it.

Why does flooding matter so much for a slab in Key West?

The island gets coastal and shallow flooding and storm surge, and one of its soil types has a seasonal high water table within six inches of the surface that floods often with the tides. That's why the flood zone and the permit come first. In the Historic District, the city also requires a Certificate of Appropriateness with the permit application for exterior work.

How much does a concrete slab foundation cost in Florida?

A 4-inch concrete slab, installed with labor and materials, usually costs about $8 to $14 per square foot in Florida. That's the market's range, not our price, and the steel, the base work and your flood zone move your number. I measure on site, and you get a written scope with the price.

How long does a concrete slab last near salt water?

A slab near salt water lasts as long as its steel stays protected, because salt is the major cause of the rebar, the steel bars inside, rusting early. Rusting steel swells and cracks the concrete from inside, so ask any contractor how the design keeps salt off it. We go over ours at the estimate.

Is my Key West address covered by the city or the county?

Not always the city. Some places with a Key West mailing address, like Key Haven, Rockland Key and the south side of Stock Island, sit outside the city, and the city sends those owners to Monroe County Floodplain Management. We check which office covers your address before anything else.

Other work that goes with a slab

  • Service

    Foundation installation

    When a slab on grade doesn't suit your lot or your flood zone, this is where we look at other foundation types for the building.

    Read more Foundation installation
  • Service

    Concrete parking lot building

    If the building needs paved parking around it, we plan the lot alongside the slab so the grades meet and water runs away from the building.

    Read more Concrete parking lot building
  • Service

    Concrete footings

    Additions, porches and new walls need footings under them, and we often pour those as part of the same job as the new slab.

    Read more Concrete footings

Get a free estimate for your slab

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Where we work around Key West

We're based in Key West and work across the island and the cities around it. Pick your area below, or call if yours isn't listed.

Call (645) 300-7417
Call (645) 300-7417