Drainage and Waterproofing Casey Key
Foundation Masters provides homeowners, condominium boards and property managers on Casey Key with engineer designed solutions to stop flooding, water intrusion, hydrostatic pressure and soil erosion.
In 1983 two property owners closed a pass at the north end of this island to protect two houses. The bay behind it lost its flushing for forty one years, and it took two hurricanes in 2024 to open it again. Everything on this page follows from that.
We are a licensed Florida engineering firm and a repair contractor in the same company, and we were the first engineering firm to pioneer the waterproofing industry in Florida. Qualifying work carries a lifetime transferable warranty.
Contractor Execution With Engineering Behind It
Foundation Masters is a licensed Florida engineering firm, CA# 30969, and a structural repair contractor. We work the whole of Casey Key, from the private north end down through the Gulf front estates to Nokomis Beach and the jetty, on single family homes, guest houses and pool structures, small condominium and association property, and the handful of commercial buildings at the south end.
The work is usually standing water that will not leave, moisture coming up through a slab, hydrostatic pressure against below grade concrete, sand disappearing from under a slab or a pool deck rather than pooling on top of it, salt staining and spalling on concrete, or the water half of a problem somebody has already been told is a foundation problem.
The difference is not the trench or the membrane. The difference is deciding what is actually wrong before anything is installed, and on an island this narrow that means being honest about where the far end of the pipe goes. We pair contractor work with in house civil engineering, geotechnical engineering in Sarasota and soil borings, so the design and the installation answer to the same firm.
A licensed Florida professional engineer signs and seals the drawings. Inspections are free.
Signs You Need Drainage and Waterproofing on Casey Key
- Standing water or soggy yards after storms
- Buckled wood floors or tile popping from slab moisture
- Water stains or efflorescence along baseboards and walls
- Mildew odor or visible mold near slab edges
- Driveway or parking area flooding that drains slowly
- Sand washing out from under a slab, a driveway or a pool deck
- Voids opening under pavers or a walkway with no puddle anywhere
- A drain that used to work and now backs up
- Rust staining, cracking or spalling on concrete near grade
The eighth one is worth a call on its own. A drain that has stopped working almost never failed at the inlet. It failed at the outlet, and the outlet is the end nobody looks at.
Eight Miles Long and Almost No Width at All
Casey Key is a skinny eight mile barrier island in Sarasota County, running between the Gulf of Mexico on one side and Little Sarasota Bay and the Intracoastal on the other. It is reached by two bridges, one of which is the one lane Blackburn Point swing bridge, awarded to the Champion Bridge Company on 2 February 1925, opened to traffic in December 1926 and on the National Register since 29 March 2001.
It is also almost entirely residential. No tall buildings, very little commercial development, one narrow twisting road, and speed limits down to fifteen miles an hour in places. That character is why people are here and it is also why the drainage problem takes the shape it does.
On a wide island there is a middle. A lot in the middle is some distance from any shoreline, and a drainage design has room to move water toward one. On Casey Key there is no middle worth the name. On most of the island a property has the Gulf on one side and the bay on the other, and both of them are tidal.
So the honest statement about drainage here is short. There is nowhere on this island that water can be sent that is not a shoreline belonging to somebody, and both shorelines rise and fall twice a day. What that leaves is sealing the structure and controlling where surface water is allowed to concentrate, and being extremely careful about what you do to an outlet.
Surface Water
Grade, collection and conveyance. The Florida Building Code requires the ground to fall six inches within the first ten feet from the foundation, and two percent on impervious surfaces. On a narrow island lot, that fall runs out of room fast.
Water Already Under the Slab
Hydrostatic pressure and capillary movement through porous concrete. No amount of surface drainage touches it, and on a barrier island the water reaching the slab is not necessarily fresh.
Material Leaving
Sand carried out from under a slab by water moving through it. Removal, not compression. Piers correct compression. Only stopping the water corrects removal.
Midnight Pass Is the Whole Argument, at Bay Scale
Everything we do comes back to one sentence. A drain is a path to somewhere lower, and it only works while the far end is open. Casey Key is the place where that sentence was tested in public, at the scale of a whole bay, and the results are on the record.
Midnight Pass sat at the north end of this island. It had already been weakened by something nobody connected to it at the time: the Gulf Intracoastal Waterway, cut in the early 1960s, gave water another way out and so reduced the tidal prism, the volume leaving Little Sarasota Bay through the pass on an outgoing tide. A smaller prism means a weaker pass. Then in 1983, when the migrating pass began to threaten two houses on the Siesta Key side, the owners hired contractors to fill it and cut a new one elsewhere. The fill worked. The relocation did not.
What followed is the part that matters to a property owner. Circulation in Little Sarasota Bay dropped. It went on to record the strongest salinity stratification of any of the five bay segments, with low oxygen in the bottom water. Seagrass fell to roughly 40 percent below estimates from seventy years earlier. Clam populations declined. None of that was the intention of anybody involved in 1983. It was the consequence of closing an outlet while the water kept arriving.
It stayed shut for forty one years. Then in autumn 2024 Hurricane Helene breached the dune between the Gulf and the old channel, and Hurricane Milton the following month opened and enlarged it. The pass now runs roughly 200 feet wide and 11 to 17 feet deep depending on the tide, and the Sarasota Bay Estuary Program expects the bay to improve. Water found its way out. It simply did it on its own schedule rather than anybody else.
Now shrink it by three orders of magnitude and put it on your lot. Your yard drain is a pass. Block or bury or silt up the far end of it and the water does not stop arriving. It sits, it stratifies, and it works on whatever it is against. The only difference is the clock. A bay takes forty years to show you. A slab takes about three wet seasons.
We Inspect the Outlet First
Most drainage inspections start at the wet spot. On Casey Key we start at the other end, because the failure is almost always there and it is almost always one of a short list.
A discharge line that daylights onto a beach face and has been buried by sand. A bay side outfall that is now below the water it discharges into for part of every tide. A pipe that was cut or crushed during landscaping or a driveway replacement and never traced. A pop up emitter that has silted shut. Or a line that was never actually connected to anything, which is more common than anybody wants to believe.
None of those show any symptom at the house until the system backs up, and by then the owner is looking at a wet slab and thinking about waterproofing. Sometimes waterproofing is genuinely the answer. Often the answer is fifty feet away at the end of a pipe and costs a fraction of what was about to be quoted.
We would rather find that and tell you than not look and sell you the bigger job. It is also the reason our inspections are free.
What Actually Falls Here
The Bradenton normal for 1991 to 2020, the nearest long record on this coast, is 56.28 inches a year, with just over 35 inches of it between June and September and August alone at 10.07 inches. That is the honest shape of a wet season here: nearly two thirds of the year in four months.
You will also see three inches of rain in an hour quoted locally as an ordinary summer storm. It is not ordinary. That is close to the peak rate in events the National Weather Service treats as extremely rare. Designing to a figure that severe and calling it routine produces numbers that sound authoritative and are not, and an owner reading a proposal cannot tell the difference.
The binding constraint on this island is not the size of the storm anyway. It is the state of the outlet when the storm arrives.
Which is a more useful thing to know, because you can do something about an outlet.
There Is No Town of Casey Key
Casey Key is unincorporated. There is no municipality, no town hall and no local building department. Permitting, inspection and floodplain determinations run through Sarasota County.
That is worth knowing because owners here often assume a rule they heard about on Siesta Key or in the City of Venice applies to them. Those are different jurisdictions. County administration is the one that governs this island.
It matters most on the flood side. In a mapped flood hazard area the lowest floor has to be at or above base flood elevation plus one foot, with certification at lowest floor placement and again at final inspection. Whether an older structure gets pulled into that requirement turns on a substantial improvement or substantial damage determination, and that is made by the county floodplain official, not by you and not by your contractor. The threshold is 50 percent of the market value of the structure alone, not the land, which on an island lot makes the denominator far smaller than the number on the tax bill.
Check your zone through the FEMA Flood Map Service Center and confirm anything that turns on a determination with Sarasota County and with counsel.
What the Work Actually Is
Foundation Masters developed the first true engineered waterproofing system in Florida to solve these issues. The process is four steps and it does not vary much.
- Excavating a trench to roughly 12 inches below the slab edge to expose the footer and wall
- Applying the Seal Tight Waterproofing System to protect below grade concrete and footings
- Designing engineered drainage piping or sump discharge to safely redirect water away from the structure and the underlying soils
- Installing gutters and grading corrections to control surface runoff
This stops moisture intrusion, prevents soil erosion, and helps reduce settlement risk under Casey Key properties. Alongside it we handle trench drain and catch basin repair, subgrade stabilization and void filling where sand has been carried out, vapor retarder work under new slabs, and seawall repair and permitting where a bay side edge is part of the problem.
What we do not do here is install a French drain and call it solved. A French drain moves water by gravity to a lower point, and on an eight mile island with tidal water on both sides there is no lower point that is not a tidal shoreline. It has to daylight or be pumped. A gravel trench through island sand also concentrates flow, and concentrated flow through loose sand is how voids start.
Casey Key and Sarasota County
The useful question on this island is which side your problem is on, because the Gulf side and the bay side fail differently.
The North End
Private road, large Gulf front estates, and the end of the island nearest the reopened Midnight Pass. Conditions here are changing right now in a way they have not for forty years, as tidal exchange returns to the north end of Little Sarasota Bay.
The Gulf Front
Open beach exposure, dune, and discharge lines that daylight toward a beach face that moves. A buried outfall on the Gulf side is not a defect in the pipe. It is the beach doing what beaches do, and the design has to expect it.
The Bay Side and the Intracoastal
Seawalls, docks, and outfalls into water whose level changes twice a day. This is where a gravity discharge is conditional by definition, and where the seawall is part of the drainage system whether or not anybody drew it that way.
Nokomis and the Neighbouring Keys
The south end at Nokomis Beach and the jetty, and up and down the coast to Siesta Key, Venice, Sarasota and Lido Key.
Casey Key Drainage and Waterproofing
Why does my yard flood even with drains installed?
Barrier islands have shallow groundwater and flat grades. After heavy rain or high tide, soils saturate and drains cannot empty because groundwater is already near the surface. On an island eight miles long and very narrow, every place a drain could empty to is a tidal shoreline, so there are hours in every day when there is nowhere lower to go.
Why is my slab letting moisture through?
Many older homes were built with slabs at or near grade. When storms drop several inches of rain quickly, the water table can rise and contact the slab, degrading vapor barriers and wicking moisture through concrete. Concrete is porous, so once the water table reaches it, capillary movement does the rest without any crack being involved.
Can you waterproof an existing home on Casey Key?
Yes. Our Seal Tight System is engineered for coastal hydrostatic pressure to keep slabs dry. It is applied to the positive side, the face the groundwater actually touches, which is why it works on a structure that is already built rather than only on new construction.
Do tides and storm surge affect my property on Casey Key?
High tides and coastal surges can raise nearby groundwater and reduce infiltration. Properly engineered drainage and waterproofing decouple the slab from groundwater pressure and route water to safe discharge. On an island this narrow the tidal influence comes from both directions, because there is Gulf on one side and bay on the other and sand between them conducts it.
Do you handle commercial parking lot drainage problems?
Absolutely. We repair and retrofit catch basins, storm pipes, and subgrade failures for retail centers, HOAs, and industrial facilities across Casey Key and Sarasota County. Details on parking lot drainage systems.
Where can I check my property flood risk?
Use the FEMA Flood Map Service Center, and take any question that turns on a determination to Sarasota County, since Casey Key is unincorporated and the county administers this island.
My drain used to work and now it does not. What changed?
Almost always the outlet, not the inlet. On the Gulf side a daylight discharge gets buried as the beach moves. On the bay side an outfall can end up below the water it discharges into for part of every tide. Lines also get cut during landscaping or a driveway replacement and never traced, emitters silt shut, and occasionally a line was never connected to anything at all. That is the first thing we check and it is often the whole job.
Has the reopening of Midnight Pass changed anything for my property?
For water quality in Little Sarasota Bay, very likely yes, and for the better. The Sarasota Bay Estuary Program expects improvement now that tidal exchange has returned. For your slab, the honest answer is that the tide range and the water table on your lot are not the things the pass changed most. Do not let anybody sell you a repair on the strength of it.
My yard is dry but a corner of the house has dropped. How?
Island sand is permeable, so water moving under a slab carries material out and leaves no puddle behind as evidence. The building settles into the space that is now missing. That is removal rather than compression, and piers will not stop it, so the water has to be dealt with either way. We would want borings before recommending a repair.
Do you install French drains on Casey Key?
No. A French drain moves water by gravity to a lower point, and here every lower point is a tidal shoreline. It has to daylight or be pumped. A gravel trench through island sand also concentrates flow, and concentrated flow through loose sand is how voids start. If somebody is quoting you one, ask where the far end goes and what it looks like today.
Why is the concrete near grade rusting and flaking?
Chlorides reaching the reinforcing steel. Corroding steel takes up more volume than the steel it replaced, so it cracks concrete from the inside and pushes the surface off. On a barrier island the chlorides come from salt spray, from surge, and from brackish groundwater. More on our steel corrosion page.
Does drainage and waterproofing work carry the lifetime warranty?
Qualifying drainage and waterproofing work carries a lifetime transferable warranty, which means it passes to the next owner of the property. Transferability is the part that matters on an island where a lot of property changes hands. The scopes and the exclusions are set out on our warranties page.
Drainage and Waterproofing Services
- Seal Tight Waterproofing System on the positive side of below grade concrete
- Engineered perimeter drainage with an outlet inspected and verified, not assumed
- Designed sump and pumped discharge where gravity is not available
- Subgrade stabilization and void filling where sand has been carried out
- Catch basin, trench drain and storm pipe repair and replacement
- Parking lot drainage systems
- Grading corrections and gutter and leader discharge
- Vapor retarder detailing under new slabs
- Seawall repair, elevation and replacement, and seawall permitting
- Sheet piling where a shoreline edge has to be cut off
When the Water Has Already Done Damage
Water that has been moving under a structure long enough stops being a drainage question. If sand has been carried away, or if chlorides have reached reinforcement, the repair is structural and the drainage work is what stops it happening again.
- House leveling on Casey Key
- Foundation repair in Sarasota and Venice
- Foundation repair on Siesta Key
- Steel corrosion in coastal concrete
- Helical piers, push piers and pipe pile underpinning
- Weathered cracks and how to read what a crack is telling you
- Structural engineer, Venice and geotechnical engineering, Sarasota
Statewide context sits on foundation repair in Florida and drainage and waterproofing in Florida.
Where Else We Work
Drainage and Waterproofing Florida · All Locations · Siesta Key · Venice · Sarasota · Lido Key · St. Armands Key · Longboat Key · Bradenton · Anna Maria Island · Holmes Beach · Port Charlotte · Punta Gorda · Cape Coral · Tampa · Flood Asset Protection · Efflorescence · Foundation Inspection Florida · Warranties
Get a Drainage and Waterproofing Inspection on Casey Key
Because Florida has no statewide waterproofing code, you need people who understand local soils, fluctuating water tables and coastal pressures. What the code does require is narrower than most owners think. The Florida Building Code requires grading that falls six inches within the first ten feet of the foundation, and two percent on impervious surfaces within that distance. It requires a real foundation drain only where a foundation both retains earth and encloses habitable or usable space below grade, which a Florida slab on grade house never does. Outside a mapped flood hazard area there is no minimum finished floor elevation above adjacent grade and no elevation certification. On this island almost nothing is outside one, so the flood rules that apply carry more weight than the building code rules that do not.
Put plainly, on a typical Casey Key house the detail that would actually keep water out is not required and is therefore usually not there. We build it anyway, because the absence of a requirement is not the same as the absence of a problem.
Under new slabs we detail vapor retarders to ASTM E1745, which caps water vapor permeance at 0.1 perms across all classes and requires 45 pounds per inch tensile and 2,200 grams puncture resistance for Class A. The 2021 IRC raised the residential requirement to a minimum 10 mil Class A sheet with 6 inch lapped joints.
Inspections are free, and on this island the first thing we look at is the far end of your existing pipe. Sometimes that is the whole answer, and we would rather find it than sell you around it.
Find Out Where Your Water Is Going
Call for direct help with flooding, moisture intrusion, hydrostatic pressure, washout under a slab or a drain that has stopped working. We will tell you what is wrong before we tell you what it costs.