What Is an FMB Sketch, and Why Does It Matter When Buying Land?
The Field Measurement Book (FMB) sketch is a survey document that comes up repeatedly in Tamil Nadu land transactions, but it's frequently mentioned without buyers fully understanding what it actually shows or why it matters — it's worth understanding on its own rather than treating it as just another item on a checklist.
What an FMB sketch actually is
It's essentially the official cadastral survey record for a specific survey number — a scaled sketch showing the plot's boundaries, dimensions, and its position relative to adjoining survey numbers, maintained by the state's survey and land records department. It's the authoritative technical record of a parcel's shape and boundaries as officially surveyed.
Why it matters specifically at purchase
- ✦It lets you verify the plot's actual physical boundaries and dimensions match what's being sold to you, rather than relying only on the seller's description
- ✦It helps identify boundary disputes or discrepancies with neighbouring survey numbers before you buy, not after
- ✦It's often needed alongside other documents when applying for building plan approval
How to use it during a site visit
Bring a copy of the FMB sketch to the actual site and check that the boundaries and dimensions shown on paper genuinely correspond to what you observe on the ground — a discrepancy here is exactly the kind of issue our site visit checklist recommends catching in person rather than relying on documents alone.
How to obtain one
FMB sketches for a given survey number can generally be obtained through the state's land records portal or the relevant taluk survey office, usually for a nominal fee. If a seller or broker can't readily produce one, request it directly rather than proceeding without it.
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Frequently Asked Questions
Is an FMB sketch the same as a patta?+
No — a patta is a revenue record establishing ownership recognition, while an FMB sketch is a survey record showing the plot's physical boundaries and dimensions. Both matter, but they serve different purposes.
What if the FMB sketch doesn't match the plot's actual boundaries on the ground?+
This is a genuine red flag worth investigating before proceeding — it could indicate an encroachment, a survey discrepancy, or a boundary dispute, any of which is worth resolving with professional help before you buy.
Do I need an FMB sketch for an apartment purchase too?+
Less directly relevant for an individual apartment unit, since your ownership there is of an undivided share plus a specific unit rather than a standalone survey number — but it's still relevant background for the underlying land the apartment building stands on.
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