Who Owns the Seawall? Riparian Rights and Shared Walls

By Ed Brannigan, Marine contractor. Reviewed by Dana Whitcombe, technical reviewer.

Seawall Repair | Boat Lift Installation Back in ’97 I got a call from a homeowner in Mullet Key, Florida. A storm had pushed the water hard enough to tilt a seawall between two lots about three degrees. The guy on the north side said it was the south guy’s wall. The south guy said the north guy had dug out his mooring and sucked the sand away. Neither one had a survey. Neither one had a deed in front of them. I waited three weeks to get paid because they were busy hiring lawyers. That happens more than you'd think. And the question that comes out of it is always the same: who is responsible for seawall repair when the wall sits on a line that two neighbors treat like a soft boundary? The answer is not always as simple as 'the guy whose land the wall is on', but that's where you have to start.

Riparian rights in plain English

Riparian rights are the rights you have to the water up against your land. If you front on navigable water in a state that uses the tideland doctrine, your property extends to the mean high water line unless there's a bulkhead line established. Most seawalls are built right on that bulkhead line, which is often the boundary between your land and the state's submerged land. So if the wall is on your side of that line, it's your wall. You own it. You're responsible for it. That's the baseline. When you deal with a shared wall, the picture changes. I've seen plenty of walls built smack on the boundary between two platted lots. The original developer may have built one continuous sheet pile wall across both back yards. That means you and your neighbor are joint owners of the wall, even if the property line runs through the middle of the concrete cap. Some states treat that as a common wall or a party wall. But don't assume the law in your county matches the one two counties over.

Shared walls: the assumptions that get you sued

A shared seawall is like a fence on the fence line, but with a lot more money on the line. Replace a hundred feet of sheet pile in Florida and you're looking at $1,200 to $2,500 per linear foot by the time you're done. That's real money. So owners get nervous when the other side starts mining sand or adding a boat lift. I've seen a guy build a 200-foot wall that protected his neighbor's whole side yard. The neighbor never wrote him a check. When the wall failed twenty years later, the neighbor sued him to fix it because the wall was 'for the common benefit'. The legal term you'll hear is 'way of necessity' or 'implied easement'. Some courts will say the wall is an easement that gives each side the right to use it, but also the duty to maintain it. Others will say no, the wall exists on one side's land, and the other side merely gets the side benefit. The best way to deal with that is never to leave it to a court. Get an agreement in writing when you buy the property, or when you build the wall. I know that's not romantic. But I've seen too many neighbors go through twenty grand in legal fees arguing over a wall that was built on a handshake. I'll digress for a minute. Back in Texas, I worked a job on what they call a "bulkhead line" where the state had actually set the boundary out into the water. The homeowner's deed said the wall was his, but the state owned the submerged land right up to the face of the wall. We ended up driving AZ 18 sheet piles from Nucor Skyline to replace the toe. So the state had the right to inspect it and even require repairs if it was threatening navigation. That surprised the hell out of him. Point is, always check whether your wall sits on a state regulatory line.

Where to start: survey, title, and the county office

Don't call a contractor first. Call a surveyor. A good licensed land surveyor can tell you exactly where the boundary line sits and whether the seawall falls entirely on one lot or straddles two. That takes about two to three weeks and costs between $500 and $1,500, depending on where you are and how much brush you've got. Then get the title work done. Look for an express easement, a covenant, or a maintenance agreement recorded in the deed history. You'd be amazed how many people never read the "reservations" paragraph on a deed. Once you know the physical and legal boundaries, get a structural engineer who works on coastal structures. They'll do a condition assessment, use a Pile Integrity Tester or just a guy on a jet ski tapping on the face with a hammer. They can tell you if the wall is a repair, a rehab, or a total replacement. That report is your ammunition. It gives you a document you can share with a neighbor or a judge, and it tells you what, exactly, needs to be fixed.

Repair vs. Replacement: the cost split is a business negotiation

If it turns out the wall is shared, you and your neighbor need to decide how to split the costs. A standard approach is to take the total linear footage and divide by the amount each side actually protects. So if your wall runs 100 feet and your neighbor's lot frontage is only 40 feet, you might pay 60% and they pay 40%. That works when both of you are seeing the same benefits. It gets trickier when one owner wants to build a bigger boat and needs a wall that's a foot taller than the original. In that case, the extra cost is on them. Don't forget permits. In most coastal states, you need a permit from the state environmental agency, sometimes from the U.S. Army Corps of Engineers, and often from your local county. The permit goes in the name of the property owner, not the contractor. If you have two owners, you should apply jointly. If one owner refuses, you can still get a permit for your own portion, but then the wall has to be physically divided. That can mean installing a separator pile or a flexible joint at the property line. I've done that half a dozen times, and it always makes the next guy's job harder. But so is a lawsuit.

What I tell homeowners who call me first

If you call me because you see a crack in the cap or some exposed sheet pile, here's what I say: get a survey and a structural report first. You're spending $2,000 to avoid a $50,000 mistake. Then talk to your neighbor like a human, not an adversary. Most people are willing to share a cost if they think they're getting a fair deal. If they're not, you can look into your local code, which sometimes lets a property owner fix a shared wall and then recover the neighbor's share through a tax lien. That's a long process, but it's real. And be honest about what you're trying to protect. If you've got a $600,000 house sitting 20 feet behind the wall, don't cheap out on a contractor job that leaves the wall leaning. The worst repair I ever saw was a guy who poured a new concrete cap over an old pile wall that had rusted through at the toe. It looked great for about six months. The first nor'easter rolled the whole mess into the water, taking part of his patio with it. Repair the structure, not just the face.

Frequently Asked Questions

My neighbor's seawall failed, and my yard is eroding. Can I fix it myself and charge him? No. If the wall is entirely on his land, you don't have the right to enter and build. You need permission or a court order. If it's shared, you can often serve a written notice of intent to repair and then sue to recover your cost. Always get that in writing before you spend. If the wall is on a utility easement, who's responsible? The utility company is responsible for their own equipment and any damage they caused, but the wall itself remains your property. Contact the utility first to see if their work caused the failure. If not, you're on the hook. Who gets the permit for a shared seawall? Usually both property owners apply jointly. Some states allow one to apply and notify the other. Never proceed on a permit that doesn't list both owners, or you'll have a legal headache. Is a seawall considered a boundary wall? It depends on the county's plat and the deed. In some cases it's a 'party wall' under state law, which means both sides share maintenance. In others, it's not. You need to verify with a title attorney.