Permit # ______________
Impervious Surface Calculation Sheet
This calculations sheet is a necessary attachment for all of the Town of Fort Myers Beach building permit
applications that involve a change to the property square footage that is covered by impervious surfaces. In
order to assure compliance with this regulation, an accurate calculation of the amount of impervious surface
coverage is needed. A short definitions of impervious surface is any hard surface that prevents or restricts
the flow of water into the soil. Examples of imperious surfaces include rooftops, sidewalks, parking lots,
patios, pools, roads or any driveway made of asphalt, concrete, gravel or paver blocks. Please complete the
following information:
Site Address: _____________________________________ Lot Dimensions: _____________________
Total Lot Area (Multiply length x width of Lot): _____________________________________________
Use the following Table to Calculate Total Impervious Surface Area ( attach additional sheet if necessary)
Impervious Surface Item
Dimensions
Area (Ft2)
Proposed or Existing House
(include steps/landings)
Proposed Addition
Proposed Accessory Building or
Garage
Existing Garage
Existing Accessory Structure #1
Existing Garage
Existing Accessory Structure #2
Sidewalks or Walkways (include
pavers)
Patio(s) (Include pavers)
Driveway(Include curbing and any
gravel/shell surfaced areas)
Recreationsl Area (basketball
court, tennis court, pools, etc.)
Other
Total new/proposed impervious surface area:
Impervious Calculation: _____ total sq.ft. of impervious surface/__________ sq ft. Total Lot Area=___(must be less than .67)
I verify that the above information is true and accurate to the best of my knowledge and that I have included all existing or proposed
impervious surfaces. I understand that providing incorrect information may result in the need to remove impervious surfaces if it is
discovered that the maximum coverage has been exceeded.
____________________________________ ____________________________________ __________________
Signature of Applicant Printed Name of Applicant Date
click to sign
signature
click to edit
FAQ Stormwater/Drainage Plans for Residential Properties
What is a stormwater or drainage plan?
A stormwater or drainage plan is a site plan that shows where water will flow. This can be shown with
arrows and/or with ground elevations. An engineered stormwater or drainage plan includes calculations
indicating how much water will be retained on site as well elevations of high points and low points and
water retention areas on the property. An engineered drainage plan must be signed and sealed by an
engineer or professional, qualified in the state of Florida.
What do I need to submit to the Town?
If your project is proposing 500 square feet, or more, of impervious surface on a parcel, your
plan will need to submit an engineered drainage plan. This plan must include calculations
showing that 1 inch (if a landlocked property) or 1.6 inches (if adjacent to water) of stormwater
will be maintained on site. In addition to showing stormwater storage, in the correct amount (1
or 1.6 inches), the plan must also illustrate that no water will leave the site due to directional
flow. The plan should also indicate the total impervious surface percentage for the parcel. The
Town does not allow more than 67% of impervious surface on a residential property.
If your project is proposing less than 500 square feet of impervious surface, your plan will need to
show, where water will be directed from the proposed impervious surface. For example, a
driveway paving permit must show that water will not be directed to the right-of-way or to an
adjacent property. The plan should indicate that the slope of the driveway will retain water on
the property which is being improved or that a drainage system is being installed to direct water
towards an appropriate storage location on site. The plan should also indicate whether there is
any increase in impervious surface. If there is any increase in impervious surface, an impervious
surface percentage must be provided.