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Subdivision Regulation Sets Standards for Buildable Lots

new home being framed in subdivision

Subdivision regulation consists of review of a proposed division of land against pre-determined standards. It is designed to guarantee adequate streets, utilities, drainage, and means of vehicular egress (leaving the development) and ingress (entering the area). Individual parcels proposed for sale, called lots, are reviewed for minimum size, appropriate shape, and access to roadways. The  process culminates in most states in the U.S. in an action of a city or town's governing body approving an overall map called a subdivision plat. Sometimes a planning commission or staff person is empowered to approve the subdivision.

The process is sometimes confused with zoning.  Indeed the two land development processes could be proceeding during the same time frame in a particular instance. But procedurally and legally, they are quite separate.

Even the name is a bit misleading. "Subdivision" leads to visions of similar houses all lined up, whereas in a legal sense in most states and towns, the word simply means the division of land into two or more parcels for purposes of legal sale.

In some locations, literally creating two separate parcels from one is a subdivision. This might be called a lot split, and each lot might be 20 acres.

Other places exempt creation of a few lots, and still others create a streamlined process for "minor subdivisions." A minor subdivision might be defined as five or fewer lots, or two or three lots, for example.

Sometimes the subdivision procedure isn't required until you are creating lots below a certain acreage, such as maybe 10 acres or 5 acres.

Purpose and Content of a Subdivision Regulation

The purpose of subdivision regulation is to assure that lots offered for sale, whether they are 40-acre "lots" or quarter-acre lots, are mapped and tied to surveying reference points so they can be located accurately in space.

It is considerably simpler to record the transfer of Lot 28 of Happy Hills subdivision, for example, than to record a page-long legal description based on dimensions, degrees, and other surveying terminology you don't even want to imagine.

The approved plat is then "recorded," just as a deed for the sale of a home or farm is recorded, in the appropriate county. Therefore the map and surveying information becomes a public record.

Another purpose of subdivision regulation is to provide a means of requiring and assuring that particular mapped public improvements, which meet the local government's specified standards, will be made by the developer of the subdivision.

These "public improvements" include streets, drainage provisions, sanitary sewers or other method of handling sewerage, provision of public water supply, and so forth.

Usually the developer must purchase a bond to guarantee that these public improvements will be constructed, or actually construct the improvements, prior to the sale of any lots. This protection prevents people from buying a lot in a subdivision only to find out they have no street access to their lot, either on a temporary or permanent basis.

The municipality also reserves the right to inspect the streets and other required public improvements to assure their construction meets their published standards before the municipality "accepts" them for public maintenance. Usually a time limit for the completion of the public streets and other required improvements is specified in the subdivision regulations also.

Even if there is no zoning law in effect, subdivision regulations can prevent the creation of lots for sale that are too small to be viable, awkwardly shaped parcels, and inadequate water lines, sewer systems, and emergency access.

More Specialized Purposes of Subdivision Plats

Of course it sometimes becomes much more complex than this. Common ground, easements granted to utilities, entry monuments, conservation areas, and many other features often are shown on the plat.

Details such as turning radii (the sharpness of a curve at a corner), lot dimensions, lot arrangement and numbering, proposed grading of the topography, stormwater runoff detention and retention facilities, street width, street type, street profiles (showing the grade or slope involved and a cross-section of the depth of each material from which the street is constructed), and so forth also are stipulated on the plat and subject to approval. Driveway slopes or steepness of the grades on a finished lot might be restricted.

Scenic vistas, wellfields, existing lakes, wetlands, or hillsides might be mapped for protection.

Subdivision regulation also might prohibit the subdivision of floodplains or other environmentally sensitive lands into separate ownerships at all. 

Sometimes 5% or 10% of the land in the subdivision is required to be "dedicated" to the local jurisdiction for open space or park land. If you do this, make sure that your state still supports the legality of such a policy. These required dedications have been decreasing in popularity, since many cities and towns realized that the small park parcels they were gaining did not present very good prospects for useful parks.

So please assure that the jurisdiction can approve which land is dedicated; otherwise, you will join the ranks of the many municipalities that have learned over the years that a ravine off the beaten path is not of much use as a park.

Many municipalities provide that the developer can choose to contribute money instead of donating land for a park. The amount of money to be contributed usually is usually a percentage of the pre-subdivision value of the land.

One particularly tricky area is what types of dead-end streets are allowed. Often suburban subdivision regulations now require cul-de-sacs, or rounded turnaround areas, to be constructed at any permitted dead ends.

A more contemporary movement is to prohibit cul-de-sacs and good old-fashioned dead-end streets entirely, by requiring that adjoining subdivisions build connections between them. A rectangular grid street system provides drivers with more options.

This is certainly a more earth-friendly and traffic-friendly solution, since all of us who live in suburbia are familiar with the "can't get there from here" syndrome. Subdivisions consisting of many cul-de-sacs really force all of the traffic out to the main road, which then quickly becomes clogged with traffic and also deteriorates faster.

The state of Virginia now is taking the lead in prohibiting cul-de-sac development, on the grounds of the increased maintenance cost for arterial roads if virtually all subdivision traffic must use that road. For more on designing the system of streets, see our page about street hierarchy.

A subdivision regulation also provides that the plat indicate the name of the subdivision and name the streets. Occasionally I've seen a planning commission rebel about some particularly unwise choice of street name, but in general the criteria for approval are simply that these names not duplicate what is otherwise present in the community.

More about the Subdivision Approval Process

Common practice has been that the municipality requires submission of as many copies of the preliminary plat as necessary to allow review by all relevant utilities, fire departments, drainage districts, parks entities, adjoining jurisdictions, and other potential commenting agencies or authorities.

Some jurisdictions want the plat to be submitted electronically, allowing a wide range of potential stakeholder agencies to view it and comment digitally for other reviewers to see.  Digital plats probably will be the norm in a very short time.  That will be a welcome relief from rooms full of yellowed paper, or outmoded formats such as microfiche.

Subdivision regulation is regarded as more technical and less political than rezoning. We can't say that it always works out that way, but in most states, reading the legal permission for towns and cities to write a subdivision regulation implies that if minimum requirements are met, the subdivision should be approved.

In many states there is no formal public hearing, so any political objections that citizens would have would involve a general gripe much like any public issue that didn't appear on a formal agenda.

In my experience, though, opposing a subdivision through political means is pretty tough. If you have the urge to do so, you missed the boat--you should have voiced your re-zoning opposition earlier in the game. Local design guidelines can be helpful if citizens frequently object to subdivisions because they don't like the aesthetic qualities of the proposed housing.

State laws govern subdivision regulation, so it is a good first step to visit your state's website and read the subdivision requirements. Keep in mind that in most states, individual locations can make stricter laws on this topic than the minimums that may be spelled out in state law.

Your local experts on this topic will be the civil engineers and attorneys who often work with  subdivision developers, even though they may have a vested interest in steering you toward a particular point of view. Planning commissions should listen to these professionals, as well as staff planners, as subdivisions and the policy relating to them are debated.

For More Perspectives Useful in Planning Subdivisions

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