Drainage and Waterproofing Lido Key
Foundation Masters provides homeowners, condominium boards and commercial property managers on Lido Key with engineer designed solutions to stop flooding, water intrusion, hydrostatic pressure and soil erosion.
Lido Key is not one island. It was a scatter of smaller islands called the Cerol Isles, dredged and joined into a single landmass and platted in 1926. The water between them was filled, and the seams are still down there.
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 Lido Key and the rest of Sarasota County on single family homes and estates, the condominium and association buildings along Ben Franklin Drive and Lido Beach, duplexes and rental property, and the commercial and hospitality property around the beach and toward St. Armands.
The work is usually standing water that will not leave, moisture coming up through a slab, hydrostatic pressure against below grade concrete, one part of a structure settling while the rest stays put, 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 this island that starts with finding out what is under the particular lot rather than what is under the island. 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 Lido 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 lot flooding that drains slowly
- One part of a slab or a driveway dropping while the rest stays level
- A crack that runs across the building rather than along it
- Sand washing out from under a slab, a driveway or a pool deck
- Rust staining, cracking or spalling on concrete near grade
The sixth and seventh are the Lido pattern and they are worth a call. Differential movement across one structure usually means the ground changed underneath it partway along, and on this island there is a specific historical reason that happens.
The Island Has Seams, and You May Be Standing on One
Before the 1920s there was no Lido Key. There was a scatter of small islands in the bay that had for some time been known as the Cerol Isles. In 1926, the dredging company run by Owen Burns cut and filled them into a single landmass for John Ringling Estates, which platted the result and renamed it Lido, the Italian word for beach.
That is a pleasant piece of local history and it is also a geotechnical description. The original isles were real ground, deposited by the sea over a long time. The spaces between them were water, and water has a bottom, usually a soft one. When the gaps were filled the new material went in on top of that bottom, and it went in the way 1920s hydraulic fill went in, which is to say quickly and without anybody specifying a density.
A hundred years later those seams are still the newest, loosest, deepest fill on the island, and they sit over what used to be a channel or a flat. So the honest answer to what is the ground like on Lido Key is that it depends entirely on which part of Lido Key, and the boundary between one answer and the other is not marked on anything.
The same thing happened next door and on a larger scale. When Arvida took Bird Key from the Ringling holdings in the late 1950s it filled shallow grass flats that had served as fish nurseries, producing a subdivision more than ten times the size of the original island. Grass flat is organic. Organic material under fill compresses for decades.
What that means for drainage is direct. Water moves preferentially through looser material, so an old filled channel is a path. And what that means for a foundation is that two houses on the same street can be sitting on two different grounds, which is why we take borings here more readily than almost anywhere we work.
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 flat island lot that fall has to be built and it has to end somewhere.
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.
Ground That Changes Mid Structure
The condition that is specific to made islands. Original key under one end of a building and filled channel under the other produces differential movement, and no drainage design alone will correct it.
Two Houses on the Same Street, Two Different Grounds
Most drainage and foundation advice treats a neighborhood as one condition. Somebody looks at what happened three doors down, or at what a contractor found last year on the next block, and reasons from it. On a natural island that is often reasonable. On an assembled one it is a guess dressed up as local knowledge.
Here is what actually varies across a few hundred feet on Lido Key. Depth of fill, from very little over original key to a great deal over a former channel. What is at the bottom of that fill, from clean marine sand to soft channel bottom to organic flat. How much consolidation is still to come, which on organic material under load can continue for decades. And how readily water travels, because looser fill is a preferential path and an old filled channel is a line of looser fill running across the island.
That combination produces the symptom this island generates more than any other we work: differential movement. Not the whole house going down, which is uniform settlement and does relatively little damage, but one end going down relative to the other. That is what cracks a building, and it is why a crack that runs across a structure tells you more than one that runs along it.
It also produces the mistake that costs owners the most. Water is found, waterproofing is quoted, the work is done properly, and the building keeps moving, because the water was a symptom of a preferential path through fill and the movement was the fill and what is under it. Or the reverse: piers are installed to stop settlement while water continues to carry material out along the same seam.
The only way to tell those apart is to look. Borings on a Lido Key lot are not an upsell, they are the difference between fixing the problem and paying for the wrong half of it. On a natural island we can often reason from conditions. Here we would rather know.
The Shoreline Is Not a Fixed Edge Either
Lido sits between New Pass to the north and Big Sarasota Pass to the south, and it has been chronically eroding for most of its existence as a single island. The beach has been renourished repeatedly, and where the sand should be dredged from has been argued over publicly and at length, including proposals to take it from Big Pass that drew years of objection from Siesta Key.
We are not going to take a side in that. What matters for a property is narrower and it is not controversial: the Gulf edge of this island moves, sometimes because the sea moves it and sometimes because a placement project moves it back. A discharge line that daylights toward the beach is pointed at ground whose elevation is not a constant.
So on the Gulf side we design assuming the outlet will change, and we check it rather than assuming it. On the bay side the constraint is the more familiar one: a receiving water that rises and falls twice a day, which makes gravity discharge conditional by definition.
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. 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.
On this island the seasonal shape matters more than any single storm anyway, because consolidation and washout are slow processes that respond to months of wet ground rather than to one afternoon.
And the binding constraint is still where the water goes, not how much of it arrives.
Lido Key Is in the City of Sarasota
Unlike most of the barrier islands on this coast, Lido Key is not its own municipality and it is not unincorporated county. It is part of the City of Sarasota, so permitting, inspection and floodplain administration run through the City rather than through Sarasota County.
Owners get this wrong regularly, usually because a neighbor on Siesta Key or Casey Key described a county process that does not apply here. Those are different jurisdictions. If your parcel is on Lido, the City is your authority.
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 turns on a substantial improvement or substantial damage determination made by the floodplain official with jurisdiction, and the threshold is 50 percent of the market value of the structure alone, not the land. On Lido, where a great deal of the value is the address, that denominator is far smaller than owners expect.
Check your zone through the FEMA Flood Map Service Center, and take anything that turns on a determination to the City of Sarasota and to 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 Lido Key properties. Alongside it we handle trench drain and catch basin repair, subgrade stabilization and void filling where material has been carried out, vapor retarder work under new slabs, and seawall repair and permitting where a bayside 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 this island the lower point is the Gulf or the bay and neither is reliably lower. Worse, on made ground a gravel trench is a deliberately constructed preferential path through material that is already the loosest thing on the lot. It has to daylight or be pumped, and on fill it wants to be designed rather than dug.
Lido Key and the Sarasota Keys
The useful question here is not which street you are on. It is whether the ground under your building is original key or filled channel, and whether it is the same at both ends.
Lido Beach and the Gulf Front
Ben Franklin Drive, the condominium and resort buildings, and the beach frontage. Open exposure, a shoreline that has been chronically eroding and repeatedly rebuilt, and discharge points that need checking rather than assuming.
The Bayside and the Canals
The residential streets and waterfront lots facing Sarasota Bay. Seawalls, docks, a tidal receiving water, and the parts of the island most likely to sit on the filled joins between the original Cerol Isles.
South Lido
The southern end toward Big Sarasota Pass and the park. A pass is a place water is squeezed, and water moves fastest where it is squeezed, so this end deals with the most active edge on the island.
St. Armands and the Neighboring Keys
Conditions on the key next door, connected to this one by the same 1926 causeway project, are on our St. Armands Key page. We also work Siesta Key, Longboat Key, Casey Key and mainland Sarasota.
Lido 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 a made island there is a second reason: water travels preferentially through the looser filled ground, so it can arrive at a low spot from a direction the surface contours do not explain.
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 Lido 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 Lido 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. With the Gulf on one side and Sarasota Bay on the other, tidal influence reaches every lot on this island.
Do you handle commercial parking lot drainage problems?
Absolutely. We repair and retrofit catch basins, storm pipes, and subgrade failures for retail centers, HOAs, resorts and association property across Lido 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 the City of Sarasota, since Lido Key is inside the city limits rather than in unincorporated county.
Is my lot on original ground or on fill?
On Lido Key it can be either, and there is no reliable way to tell from the surface. The island was assembled in 1926 from a group of smaller islands called the Cerol Isles by dredging and filling the water between them, so some lots sit on ground that was always there and some sit over a filled channel. A boring answers it for your specific parcel in a morning, and it changes what the right repair is.
One end of my house has dropped and the other has not. Why?
That is differential movement and it is the signature problem of a made island. If the ground under one end is original key and the ground under the other is fill over a former channel bottom, the two ends behave differently under the same load and the same weather. Uniform settlement does relatively little damage. Differential settlement is what cracks buildings, which is why a crack running across a structure is more informative than one running along it.
Will waterproofing stop my house moving?
Only if water is what is moving it. If material is being carried out from under the slab, stopping the water stops the cause. If the fill or the organic material beneath it is still consolidating under load, that is compression and waterproofing will not address it, though water usually makes it worse. Those are opposite mechanisms with similar symptoms, and telling them apart takes borings rather than a look around the yard.
Do you install French drains on Lido Key?
No. A French drain moves water by gravity to a lower point, and here every lower point is a tidal shoreline. There is also a problem specific to made ground: a gravel trench through fill is a deliberately built preferential path through the loosest material on the lot, which is the opposite of what you want where washout is already a risk. It has to daylight or be pumped, and on fill it wants to be designed.
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 designed for fill rather than dug into it
- Designed sump and pumped discharge where gravity is not available
- Subgrade stabilization and void filling where material 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 bayside edge has to be cut off
When the Water Has Already Done Damage
On made ground the structural side comes up more often than it does elsewhere, because fill over an old channel bottom can be doing two things at once. The drainage work stops the water. The structural work corrects what has already moved.
- Foundation repair on Lido Key and house leveling on Lido Key
- Foundation repair in Sarasota
- Foundation settlement repair, which explains uniform settlement, tilt, sagging and hogging
- Helical piers, push piers and pipe pile underpinning through fill
- Weathered cracks and how to read what a crack is telling you
- Steel corrosion in coastal concrete
- 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 · St. Armands Key · Sarasota · Siesta Key · Longboat Key · Casey Key · Venice · Bradenton · Anna Maria Island · Holmes Beach · Apollo Beach · Indian Rocks Beach · Clearwater · Tampa · Flood Asset Protection · Efflorescence · Structural Engineer Venice · Foundation Inspection Florida · Warranties
Get a Drainage and Waterproofing Inspection on Lido 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 Lido 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. On this island the first thing we want to establish is what is actually under your building, because the answer changes across a few hundred feet and it decides which half of the problem you are looking at.
Find Out What Is Under Your Building
Call for direct help with flooding, moisture intrusion, hydrostatic pressure, one end of a structure dropping, or washout under a slab. We will tell you what is wrong before we tell you what it costs.