Summary:
You’ve decided to finally build that fence. Or maybe it’s an addition, a pool, or a shed in the backyard. You’ve got a contractor lined up, a budget in mind, and a rough timeline. Then someone mentions you might need a survey — and suddenly you’re not sure what that means, whether you actually need one, or where your property even ends.
That confusion is more common than you’d think, especially in Nassau County, where lot lines are tight, building departments are strict, and the rules can vary from one village to the next. This page will help you understand exactly what a building site survey is, when your project requires one, and what your options are before you make a call.
What Is a Building Site Survey?
A building site survey is a professionally prepared document that shows the legal boundaries of your property, the location of any existing structures on it, and — depending on what you’re building — where your proposed structure will sit in relation to those boundaries. It’s produced by a licensed Professional Land Surveyor and carries a certified stamp that makes it legally valid for permit submissions, real estate transactions, and boundary disputes.
Think of it as the document that proves what you own and where it ends. Not a tax map. Not a sketch from Google. A certified, legally binding record of your property as it exists on the ground.
For homeowners in Nassau County, a building site survey is most commonly required when pulling a permit for new construction, additions, pools, fences, decks, or accessory structures. It tells the building department that your project fits within your lot and respects the setback requirements — and in Nassau County’s 64 incorporated villages, those requirements vary significantly from one municipality to the next.
How a Building Site Survey Differs From Other Survey Types
This is where a lot of homeowners get confused, and understandably so. The terms get used loosely — boundary survey, title survey, plot plan, site plan, building site survey — and they’re not all the same thing.
A boundary survey establishes the legal edges of your property. It’s the foundational work that most other surveys build on. A title survey is typically used in real estate transactions to confirm ownership and flag any easements or encroachments that might affect the sale. A topographic survey maps the physical terrain — elevation changes, drainage patterns, slope — which architects and engineers need for larger projects.
A building site survey, in the context of a permit application, combines elements of a boundary survey with the specific documentation your building department needs to review your project. It typically shows your property lines, the location of existing structures, the proposed footprint of what you’re building, setbacks from the lot lines, and any easements that might affect placement. In some Nassau County municipalities, this is also called a plot plan or site plan — but the underlying survey work is the same.
The distinction matters because if you walk into your village building department with the wrong type of document, your application gets kicked back. In Nassau County, where the Town of Hempstead, the Town of North Hempstead, the Town of Oyster Bay, and 64 separate incorporated villages each run their own permit offices with their own submission requirements, that’s not a hypothetical — it happens regularly.
A foundation location survey — sometimes called a spot survey — is a related document that gets required after construction begins. Once your foundation is poured, many Nassau County municipalities and lenders require a certified survey confirming the structure was built in the correct location with proper setbacks before they’ll allow work to continue. It’s worth knowing this exists before you start, not after.
When Nassau County Projects Require a Building Site Survey
The short answer: almost any permitted project. In Nassau County, permit applications for new construction, additions, pools, fences, sheds, and decks routinely require a survey or plot plan showing your property boundaries and the location of existing structures. The specific requirements depend on your municipality — your village building department will tell you exactly what they need — but a current, certified survey is the baseline for most of them.
What trips people up is assuming that a small project doesn’t need documentation. A fence feels minor. A small shed feels minor. But in Nassau County’s densely developed neighborhoods — Levittown, East Meadow, Bellmore, Merrick — where lots can be 5,000 to 7,500 square feet, the margin between your proposed structure and your neighbor’s property line can be measured in inches. Building departments know this, and they require documentation accordingly.
There’s also a timing issue worth understanding. If you build without a survey and your fence ends up six inches over the line, that fence legally becomes your neighbor’s property. If it lands exactly on the line, it becomes a jointly owned boundary fence — which means your neighbor has legal say over what happens to it. Neither outcome is something you can easily undo. The cost of correcting an encroachment — removing and rebuilding a fence, relocating a structure, navigating a legal dispute — far exceeds the cost of getting the survey done correctly before you start.
Properties within 500 feet of a Nassau County or state road also trigger additional review through the Nassau County Planning Commission, adding another layer of documentation that a qualified local surveyor will already know to account for.
How to Find Your Property Lines Before Calling a Surveyor
Before you pick up the phone, there are a few things you can try on your own. None of them replace a certified survey, but they can give you a useful starting point — and help you understand what you’re working with before you talk to a professional.
The four main approaches Nassau County homeowners typically use are: reviewing the deed description, checking the Nassau County Land Records Viewer, looking for physical property markers on the lot, and locating a prior survey from your closing documents or county records. Each has real value. Each also has limits.
Property Line Markers: What They Are and How to Find Them
Physical property line markers — also called monuments or property boundary markers — are the most tangible evidence of where a surveyor previously established your lot lines. In New York State, these are typically iron pins, rebar stakes, or concrete monuments set at the corners of your property during a prior survey. Some older lots use PK nails set into pavement at the lot corners along the street.
If your property was surveyed at some point in the past — which most Nassau County properties were, even if it was decades ago — those markers may still be there. They’re usually set flush with or just below grade at the corners of your lot, which means they can be hard to spot without knowing exactly where to look. A metal detector can help locate iron pins and rebar stakes that have settled below the surface or been buried by years of lawn maintenance and landscaping.
The problem is that markers go missing. Construction activity, landscaping projects, fence installations, and simple time can disturb or remove them. In Nassau County’s older neighborhoods, where many properties haven’t had formal survey work since the 1960s or 1970s, it’s common to find that one or more corner markers are simply gone. Even when you do find a marker, interpreting what it means — whether it’s actually your corner, or a remnant from a prior subdivision, or a utility marker that looks similar — requires training that most homeowners don’t have.
Finding a marker is a starting point. It is not a property line determination. Only a licensed Professional Land Surveyor can legally certify where your boundaries lie in New York State.
Using Nassau County GIS and Deed Records to Research Your Lot
Nassau County provides a public tool called the Land Records Viewer (lrv.nassaucountyny.gov) that lets you look up parcel data, tax maps, and approximate lot dimensions for any property in the county. It’s genuinely useful for getting oriented — you can see your lot’s rough shape, its listed dimensions, and how it relates to surrounding parcels. Most homeowners who do any research before calling a surveyor end up here at some point.
But the Land Records Viewer describes itself as a research tool, and that’s exactly what it is. The parcel outlines it shows are based on tax map data, not legally surveyed boundaries. They’re approximations. In Nassau County, where lots can be small and tightly packed, the difference between an approximate boundary and a certified one can be significant enough to affect where you’re allowed to build.
Your deed description is another place to start. Deeds typically include a metes-and-bounds description of your property — a series of directions and distances that trace the boundary of your lot. If you don’t have your deed handy, it’s a public record available through the Nassau County Clerk’s office. Reading a metes-and-bounds description takes some practice, and older deeds sometimes reference landmarks that no longer exist, but it gives you the legal description your surveyor will use as a starting point.
A prior survey — if you received one at your real estate closing — is the most useful document you can have in hand before calling a surveyor. It tells the surveyor what was established before, what monuments were set, and what research has already been done. Whether that prior survey is current enough for your building department is a separate question, and one worth asking directly. Many Nassau County municipalities require a survey that reflects current conditions, and a survey from 30 years ago may not show additions, changes to neighboring structures, or updated setback standards.
Getting a Building Site Survey Right the First Time in Nassau County
Nassau County’s permit process isn’t designed to be difficult — but it does require the right documentation, and that documentation needs to be prepared by someone who knows the county’s specific rules. With 64 incorporated villages each running their own building departments, what satisfies one municipality may not satisfy the next. A surveyor who knows this landscape doesn’t just hand you a certified map — they hand you a document that’s formatted to clear your specific permit review on the first submission.
That’s the practical value of working with Islandwide Land Surveyors. We’ve been doing this work in Nassau County for over 50 years, and we bring a working knowledge of the specific towns, villages, and building departments you’re actually dealing with — not just a general familiarity with New York State surveying requirements.
If you’re planning a project and you’re not sure whether you need a survey, what type you need, or how long it will take to get one, we offer free, no-obligation quotes with transparent pricing — no guessing, no surprises. Reach out to us before you start, not after something goes sideways.
