bedroom suite could violate
zoning laws if you raise the
height of the roof.
Zoning regulations cover four basic building issues: height, use, bulk, and density. These rules specify the maximum height of a building; its allowable uses, which include residential, commercial, industrial, and home-office considerations; the width and depth of the building; and the number of units allowed per acre.
Zoning regulations were not in use until the early to mid-1900s. In addition, regulations are modified on a regular basis to address changes in the community. Therefore, if you're in an older neighborhood, your type of house may not be consistent with the zone where you live. For example, you may have a single-family home in a commercial or multifamily zone. This is known as a preexisting, nonconforming use. (Although this sounds like a bad thing, it simply means that your use is "grandfathered," or permitted to continue, as long as you don't make any significant changes in any of the four basics covered by zoning regulations.)
Generally speaking, only use, height, and bulk restrictions affect residential building additions. If you want to add a bedroom, greenhouse, kitchen, family room, or other space that is consistent with a residence, you usually can relax any worry about use considerations. However, there is one significant caveat: If your house falls into the preexisting, nonconforming use category, you will need an approval called a variance from the municipality to build an addition.
A variance permits an exception to the rule for your specific situation. Without the variance, you cannot add the addition. Even if your house is in conformance with current zoning rules, you will need a variance if you propose an addition that is taller than the maximum height for the zone or wider than the maximum width. In addition, a variance is required if you change the use of a building such as converting your garage to a florist's shop.
Obtaining a variance not only costs money, but it also can involve significant time and effort. You may need to hire a lawyer or other professionals (planner, engineer, or architect) to help you prove that the variance is necessary.
Variances are granted based upon special considerations such as promoting public health, safety, morals, and general welfare; securing safety from fire, flood, panic, and other disasters; providing adequate light, air, and open space; or exceptional and undue hardship relating to the specific site. You also have to show that there will be no negative impact upon the community or your neighbors. Variances are usually decided by a zoning board of local citizens chosen by the governing body of the municipality.