February 17, 2013

Can I Turn a Shed Into a Tiny House?

Small guest cottage
The homeowner built a wood deck in front of the shed and made it look "oh so homey".

Recently we've seen several people ask the question of whether you are allowed to turn a shed into living space on some Tiny House-related Facebook pages and groups. When the same topic came up on our own Historic Shed page, we decided we should write about the idea. Understandably, it is an appealing concept to many who dream of an unencumbered Tiny House lifestyle: buy an inexpensive set of 4 walls and a roof set on your property, finish out the interior, and live a debt free life. While, we can't speak to the practicality of this idea everywhere, we can give some insight into the issues you might run into with this idea in Florida so you can plan accordingly.

Zoning: Zoning codes are basically a list of what and where things can be built within a community - how tall, how much of the lot they can cover, how they can be used, parking requirements, landscaping, etc. They vary from town to town, and even from neighborhood to neighborhood, so you need to check individual local zoning requirements for any parcel you are considering building on. Before planning to place even a shed for storage in your yard, these are some items to look into related to the local zoning codes and small buildings:

  • Use - Zoning will list what type of building uses are permitted within an area. A parcel may be zoned commercial, industrial, residential, residential multi-family or allow for a combination/ variety of uses. It will also describe what type of accessory uses may accompany the main use of the parcel.
  • Size - Local zoning usually spells out minimum and maximum sizes for new construction in an area. It may be a percentage of the lot size or a square foot limit. Height limits, as well as building footprint sizes are listed. While some areas list minimum sizes for primary residences, many areas do not.
  • Quantity - The number of units that may be placed on any particular parcel is also typically listed in zoning code. This is particularly important for anyone thinking of creating of community of multiple little houses or adding a second unit on a residential lot.
  • Accessory Buildings - Most zoning codes will define whether accessory buildings/ accessory dwelling units (ADUs) are allowed in a particular area, and how many. In addition, size and height restrictions and where they may be placed in the yard will be defined. They will also tell what type of uses are allowed in the accessory structures. This may allow for storage sheds, detached home offices, and/or accessory dwelling units.  If a shed is allowed, but not an accessory dwelling, you can not legally renovate the shed as an accessory dwelling. As a side note, the difference between a home office and an accessory dwelling unit is often defined by the presence of an oven.
  • Using a Shed on a Trailer as a Tiny Houses on Wheels - Since THOWs were not around when most Zoning Codes were written, you are unlikely to find a section in the zoning code that tells you whether you can legally live in a THOW on your property. Many municipalities apply RV rules to THOWs, so your best bet may be to search for RV living regulations. You may also have luck convincing zoning that Mobile Home regulations are more appropriate for you THOW, should your property allow them.

Building Code: In order to build a residential building in Florida, you will have to get a building permit from the local building department and go through a series of inspections before you can occupy your residential building. Permits require a set of plans and elevations that meet design criteria in the Florida Building Code. Most times, the plans are required to be reviewed and approved by a licensed structural engineer. Sheds in Florida are not held to the same construction standards as residential buildings. This is good for shed manufacturers, but means that you should be sure that you can comply with the following if you try to convert a shed into a dwelling unit:

  • Wind Load Design - The 2010 (5th Ed.) Florida Building Code instituted 3 new Wind Speed Maps for wind load design. Residential buildings (Type II) are designed for a higher wind load rating than buildings designed for use as storage sheds (Type I). This means that wall construction, windows, doors, roof material, etc. may not meet residential code requirements in your area rather than the lesser shed regulations. UPDATE: The Code edition was updated at the end of 2017.
  • Foundation - There are exceptions in the code for concrete foundations for sheds that allow them to be substantially smaller than for residential construction. In addition, a  vapor barrier is not required under the slab for sheds, but is for residential construction.  Other common shed tie down foundations are often not allowed for residential construction at all.
  • Room sizes - Florida Building Code requires that at least one habitable room in a residence be a minimum of 120 sf. Bathrooms must meet certain clearances and contain a lavatory, toilet and shower. No habitable room may be less that 7' in either dimension. This applies to all rooms other than the bath, kitchen, closets and utility rooms. Your plans will have to show that it meets all these size requirements. In most cases, you can build a residence as small as 150 sf and meet FL Building Code requirements. As noted above, zoning regulations for your property may require a larger footprint.
  • Room heights - Ceiling heights within residences are a minimum of 7' (6'-8" in baths). If you plan to install a loft, be particularly aware of this restriction. Also, many manufactured sheds have 6' high side walls.
  • Flood Zones - Storage sheds may be installed below the design flood elevation in flood hazard areas. Residential buildings must be raised above the design flood elevation.
  • Windows - Windows of certain sizes are required in living spaces for egress, air quality, and light. Make sure your shed windows are large enough to meet these requirements.
  • Impact requirements - "Storage sheds that are not designed for human habitation and that have a floor area of 720 square feet (67 m2) or less are not required to comply with the mandatory wind-borne debris impact standard of this code." This means windows in sheds are not impact rated in High Velocity Wind Zones and do not have the required shutters that a residential building would have.
  • Placement on site - "Detached tool sheds and storage sheds, playhouses and similar structures are not required to provide wall protection based on location on the lot. " This means that walls may not meet the required fire rating that a residence in the same location would be required to have.

Other things to know: In some areas of Florida, you may build a storage shed under a certain size without a permit. This does not mean than you can build a building for other uses, such as a residence, under that square footage without a permit. And you may not change the use of a building without a building permit legally (if you pull a permit for a shed, it can only be used as a shed). Modifications after the fact, done without a permit, can result in you being required to remove your building from the property. In addition, some gated communities have their own set of design standards. This may include regulations on accessory buildings, how buildings should look, and provide minimum sizes for new construction above and beyond what is called out in zoning code.

I doubt I have identified all the potential issues with using a shed as the starting point for a residence in Florida, but at least this will help some who are considering the idea. Personally, for all the adaptations that could be required, I would think starting from scratch would be just as easy, albeit perhaps more intimidating. If so, feel free to give Historic Shed a call and we can build a shell that will meet all Florida Residential Building Codes for your dream cottage lifestyle and include your Engineered Drawings.

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