You can generally assume that if you own a lot in a subdivision that was recorded before some change in the zoning codes creates new restrictions-such as limiting new construction to lots of sizes or shapes different than those on the plat of your parcel-your rights will not be "grandfathered" when constructing a new building on your lot. Various "vesting" rules have been created in court cases and statutes which might allow you to complete a building you have started (or, in some jurisdictions, have merely obtained permits for) before a change in the codes. Alternatively, your lot might be grandfathered for a specified number of years.
In general, though, the mere ownership of a lot made nonconforming by a change in zoning codes confers no special rights. Most often this issue arises in municipalities with old plats describing tiers of narrow lots, e.g., 25' wide, filed before new zoning codes require a minimum lot width, e.g., 50'. Houses already built on 25' wide lots will typically be allowed to remain as nonconforming structures; construction in progress on 25' wide lots when the new zoning code takes effect will typically be completed under vesting doctrines, but any subsequent construction will typically require the combination of two or more adjacent lots.