How To
Who Built This House? Researching a Bohemia Home
Deeds, tax maps, aerial photographs and old atlases — where the records are, what each one will actually tell you, and where the trail usually goes cold
Almost everyone who owns an old house in Bohemia has wondered about it. Who put the addition on the back? Why is the kitchen floor two inches higher than the hall? Whose initials are those in the concrete by the side door? The answers exist, most of them in public records, and a determined afternoon will get you further than you expect. This is a guide to where those records are kept, what each one can and cannot tell you, and roughly the order to work through them.
Before You Start
Which Bohemia House Do You Have?
Bohemia has two housing stocks, and they take two different kinds of research. The first is the village itself — the farmhouses, cottages and storefront-and-flat buildings that went up along Locust Avenue, Church Street, Smithtown Avenue and the lanes between them from the 1860s through the 1920s. The second is everything built in the great postwar expansion, when the potato fields and pine lots on the edges of the hamlet were bought by developers, cut into tract streets and filled in with ranches and split-levels. Both are Bohemia. Both have a history. But a house from 1958 will not appear on any nineteenth-century atlas, and a house from 1890 will not have a building permit.
You are really chasing three separate questions, and it helps to keep them apart: when the house was built, who has owned and lived in it, and what the land was before the house. Different records answer each one, and it is common to nail down the second and third while the first stays frustratingly approximate.
Step One
Get Your Tax Map Number and Your Own Deed
Suffolk County identifies every parcel by a four-part number — district, section, block and lot. Islip is District 0500. That number, not your street address, is what most county systems actually run on, and having it written down before you start will save you an hour. The county’s Real Property Tax Map Viewer will find it from your address, and will also give you the current owner of record and the acreage.
Then go and find your own deed — the one you signed at closing, probably in the folder with the title insurance. In the upper right-hand corner is a Liber (book) number and a page number: that is where your purchase is recorded in the county’s books. At the end of the property description you will often find a reference to the previous deed, with its own Liber and page. Write both down. That single back-reference is the first link in the chain, and the whole method that follows is simply pulling on it.
Step Two
Read the Deeds Backwards
The Suffolk County Clerk holds land records from the mid-1600s, and the office publishes its own instructions for exactly this task under the heading Researching the History of Your House. The method is to take the earliest Liber number you have, pull that deed, find the reference it makes to a still earlier one, and keep going — each deed handing you the next.
Some of this can be done from your kitchen table. The Clerk’s online records system covers documents recorded and imaged from 1987 to the present, and searching it is free — by address, by tax map number, by name, or by Liber and page. Viewing the document images themselves requires a paid subscription. For anything before 1987 you have to go east, to the Records Room at the County Center, 300 Center Drive in Riverhead.
If your deed gives you no Liber number to start from, you can still work backwards by name. Land records are indexed twice, by grantor (seller) and grantee (buyer), and the shape of those indexes matters: from 1660 to 1950 the whole county is indexed in one alphabetical run; from 1951 to 1969 the books are divided by town first and alphabetically within each town; from 1969 forward you use the terminals in the Public Access Room. So look up the person you bought from, find the deed by which they acquired the property, and repeat.
Two things worth knowing while you are in that room. The mortgage books are in there too, and a mortgage taken out on a vacant lot is often the closest thing you will get to a construction date — people borrowed to build. And when a deed transfers property to someone as the heir of a person who died, write that name down and look up the will at Surrogate’s Court: wills describe houses in a way deeds almost never do. Plan on most of a day. There are copiers in the Records Room at 25¢ a page, some of the oldest volumes are sealed in Mylar and cannot be photocopied at all, and nothing is pulled from storage after 4:15.
Step Three
The Town: Permits, Occupancy, and a Date to Distrust
The Town of Islip’s assessment roll is online and free, and it will hand you a year built. Treat that number as a starting point and not an answer — it is an assessment figure, entered for tax purposes, sometimes decades after the fact, and for older village houses it is frequently a round-numbered guess.
The better town record is the permit file. Building permits generally were not issued anywhere in Suffolk County before the early 1920s, so for a genuinely old Bohemia house there will be no original permit to find. What there will be is a paper trail of later work — the addition, the dormer, the detached garage, the oil tank — and the file often opens with a stated “date of origin” for the house. Keep in mind that this date was supplied by whoever filled out the application, and they were frequently guessing too.
Those files live with the Building Division Records Section at One Manitton Court in Islip, and they are released through a Freedom of Information request. You can file one online at islipny.gov/foil or ask the Records Office directly at (631) 224-5470. Request the certificate of occupancy along with the permit history; a C of O tells you when the town accepted the building as finished, which is often the tightest date you will ever get.
Step Four
Watch Your Roof Appear from the Air
This is the trick most people never think of, and for a postwar house it is the single fastest way to bracket a date. Suffolk County has been photographed from the air repeatedly since the 1920s, and the county’s cartography office keeps a run of historic aerial photography covering roughly 1928 to 2001. Several of those years are layered into the free Suffolk County GIS Viewer: find your lot, then step backward through the years until the roof disappears. The gap between the last empty frame and the first one with a house on it is your construction window, and it is evidence no one can argue with.
The high-altitude 1938 federal flights, made for the Department of Agriculture, are the earliest wide coverage of this part of the Island, and they catch Bohemia while it was still mostly farm lots and pine. Stony Brook University’s library holds a substantial collection of Long Island aerial photography as well. Watching your street fill in frame by frame is also the clearest picture anyone will ever give you of the suburban boom arriving.
Step Five
The Maps That Put a Name on a Dot
Nineteenth-century atlases of Long Island did something modern maps do not: they printed the owner’s surname beside each building. The 1873 Beers atlas is the best of them for this town, detailed down to individual structures, and the County Clerk’s Historic Documents Library keeps bound atlases of Suffolk County starting around that date — several of which mark houses, sometimes with a number indicating how many stories. If your house is old enough to be on one, a Czech surname printed on your lot is about as satisfying as this research gets.
Sanborn fire insurance maps are the other great building-by-building source, drawn for insurers and color-coded by construction material. Bohemia’s coverage is thin and slightly maddening. Sanborn surveyed commercial cores rather than open countryside, and it worked this area out of Sayville: the Library of Congress catalogs Sayville sets from 1886 through 1949, but the two whose coverage notes actually name Bohemia — the 1925 edition and its 1925–1949 revision — are among the ones the Library has not put online. The Sayville sheets you can view free on screen, from 1886 to 1915, stop short of us. For the Bohemia sheets you need film or paper: the County Clerk’s Historic Documents Library holds a partial Sanborn collection, and the complete New York State run is on microfilm at Stony Brook.
For a tract house, the map that matters is a different animal entirely: the filed subdivision map, recorded with the County Clerk when a developer cut a farm into building lots. It gives you the name of the subdivision, the date it was filed, the lot numbering, and the developer — and your deed almost certainly refers to it by number. That filing date is a hard floor. Your house cannot be older than the street it stands on. The Society also keeps a growing collection of local maps on this site.
The One Nobody Knows About
Check Whether Someone Already Did This in 1990
Before you spend a day in Riverhead, spend five minutes here. Beginning around 1972 and in earnest through the 1980s, historic building-structure inventories were compiled for the hamlets of Islip Town — survey forms recording construction date, previous owners, condition, and why the building mattered. The Connetquot Public Library has digitized them and put them online, free, arranged by hamlet and then by street.
Bohemia’s folder covers Church Street, Hubal Street, Karshick Street, Lakeland Avenue, Locust Avenue, Smithtown Avenue and Union Street, with most of the forms dated 1990 and many accompanied by photographs taken in 2008. The entries are filed under house number and family name — the Svoboda house at 1151 Locust, the Hamous house at 1225, the Behounek house at 1440, the Kouril house and Ruzicka greenhouses at 1519, which is the property the Society’s own museum stands on. If your address is in there, a good deal of your work was done thirty-five years ago by someone standing on your front lawn with a clipboard.
Step Six
Put People Back in the Rooms
A chain of title gives you owners. The census gives you households — everyone under the roof, their ages, their birthplaces, their trades, and, because enumerators walked door to door, your neighbors in order down the street. Federal censuses are available from 1850 through 1950, and New York took its own in 1855, 1865, 1875, 1892, 1905, 1915 and 1925, which conveniently fills the gaps. Survival varies by county and year, so check before you travel.
For a Bohemia house there is one more county holding worth knowing about: the Suffolk County Clerk keeps naturalization records from 1853 to 1990, both declarations of intention and petitions. For families who arrived from Bohemia and Moravia, those papers often carry the village of origin, the ship, the date of arrival and the address at the time of filing — which may well be your address.
Then search the newspapers, and search them for the family name as well as the address. NYS Historic Newspapers has digitized the Suffolk County News from 1888 to 2022, along with the Islip Bulletin, the Ronkonkoma Review and others, all free and full-text searchable. Local weeklies of that era printed everything: who was building, who sold a lot, who had visitors from the city, who was ill, who died. One line in a 1911 column reporting that a neighbor has begun the erection of a dwelling on Church Street would be worth more than any assessment record — and lines like that are in there, waiting for someone to search the right name.
A Note on the Record
Where the Trail Usually Breaks
Four things trip up nearly everyone, and it is better to expect them.
Your address is younger than your house. Bohemia’s roads were sand tracks for decades, and house numbering came late. An 1873 atlas gives you a surname on a dot, not 1225 Locust Avenue; matching that dot to a modern parcel is a job of overlaying maps, not of reading an address.
Deeds convey land, not buildings. A deed will rarely say a house exists, let alone when it was built. A sharp jump in the sale price between two deeds a few years apart is often the only signal that something got built in between — suggestive, not proof.
Buildings moved. This is not a technicality here. Bohemia’s first schoolhouse was sold at auction for $100, hauled down to Locust Avenue and reopened as Cervenka’s grocery. Barns became houses, houses became stores, and a structure that started life two streets over will wreck any chronology built purely from maps.
Czech names were spelled by ear. Clerks, census takers and newspaper typesetters wrote down what they heard, and diacritics did not survive the crossing. Search for every variant you can think of, and search by first name and street when the surname fails you.
When the records genuinely run out, say so. A house that “appears on the 1938 aerial and does not appear on the 1873 atlas” is an honest finding. A house confidently dated 1902 because a real estate listing said so is not.
Close to Home
Three Places You Can Reach Without Leaving Town
The Connetquot Public Library, 760 Ocean Avenue, is the best free research room in Bohemia and most residents have never used it as one. Besides the building inventories, it holds an index of local obituaries, a genealogy blog, and the Memory Lane oral history project — recorded interviews with people who remember these streets. Its database shelf includes Ancestry Library Edition (in-library use), HeritageQuest, Fold3, MyHeritage, and ProQuest runs of Newsday back to 1940 and the New York Times back to 1851.
The Suffolk County Historical Society at 300 West Main Street in Riverhead keeps a research library of more than 20,000 volumes — genealogies, town records, ledgers, diaries, photographs, maps and atlases, cemetery transcriptions, and federal and state censuses for Suffolk County on microfilm. The stacks are closed, so staff retrieve materials for you; the library is open Wednesday through Saturday afternoons and it is worth calling ahead.
This Society holds photographs, postcards, maps, oral histories and family papers, much of it not online anywhere. Start with our photo albums, the founding families pages, and the stories behind Bohemia’s street signs — if your road carries a family name, that family is part of your house’s story. For what a finished piece of this research can look like, see Then and Now: 812 Locust Avenue, one house photographed twice about 120 years apart.
Help Us Fill In the Blanks
We would like to help, and we would like a copy. If you are starting on your own house, write to the Society before you drive to Riverhead — we may already hold a photograph of your block, a family name that matches your deed, or an oral history from someone who grew up in your rooms. We cannot do the research for you, but we can usually save you a trip.
And when you finish, send us what you found: the chain of deeds, the construction date and how you established it, the names of the families who lived there, and above all photographs — the house before the siding, the barn that is gone, the people on the porch. House by house, those files become the record of what Bohemia actually looked like, and no one but the owners can build it.
You can reach us through the contact page or by way of Share Your Story. Corrections to anything on this page are welcome too — the people who have done this work know the pitfalls better than any guide does.
Sources: Suffolk County Clerk, “Historic Documents Library — Researching the History of Your House” and “Online Records”; Town of Islip Assessor and Building Division Records Section; Suffolk County Real Property Tax Map Viewer and Suffolk County GIS Viewer; Connetquot Public Library, Town of Islip Historic Building-Structure Inventory, Obituary Index and Memory Lane oral history project; NYS Historic Newspapers, Suffolk County collection; Library of Congress Sanborn Maps Collection; Suffolk County Historical Society Library & Archives.
Office hours, fees and access rules change. Everything here was checked in September 2026, but call ahead before you make the drive to Riverhead or Islip, and tell us if you find something out of date.