Building Planning and Construction

Building Planning

It is important for design and construction professionals to adhere to basic standards for building a home, starting with the structural frame. Strengthening the structural frame of a house includes creating a “complete load path” within the home, which is a method of construction that uses a system of wood, metal connectors, fasteners (like nails and screws) and shear walls to connect the structural frame of the house together. A complete load path is like a chain that ties the house together from the roof to the foundation. A home is more likely to withstand a seismic or high wind event and stay intact when all parts of the house – roof, walls, floors and foundation – are connected together securely.

The Florida Building Code requires all buildings and structures, and all parts thereof, to be constructed in a way that safely support all loads, including dead loads, live loads, roof loads, flood loads and wind loads. And a continuous load path between foundations, walls, & roofs must be provided. (FBC- Residential R501.2 Requirements and R601.2 Requirements)

Florida Building Code Loads

Dead Loads – The weight of materials of construction incorporated into the building, including walls, floors, roofs, ceilings, stairways, finishes, cladding and other architectural or structural items, and the weight of fixed service equipment such as cranes, plumbing stacks and risers, electrical feeders, heating, ventilating and air-conditioning systems and fire sprinkler systems.

Live Loads – Those loads produced by the use and occupancy of the building or other structure and do not include construction or environmental loads such as wind load, snow load, rain load, earthquake load, flood load or dead load.

Live Loads (Roof) – Those loads produced (1) during maintenance by workers, equipment and materials; and (2) during the life of the structure by movable objects such as planters and by people.

Nominal Loads – The magnitudes of other design loads including soil, wind, snow, rain, flood and earthquake.

Constructing homes in accordance with the provisions of the code should result in a system that provides a complete load path, which will transfer of all loads from their point of origin through the load-resisting elements to the foundation.

Exterior Walls

Exterior walls of the house must create a weather-resistant exterior wall envelope and include corrosion-resistant flashing. One purpose of the wall envelope is to prevent the accumulation of water within the wall assembly. One way it can be accomplished is by using weather-resistant sheathing paper such as No. 15 asphalt felt or other approved water-resistive barrier over studs or sheathing of all exterior walls. Concrete and masonry walls properly constructed and flashed in accordance with code specifications do not require a weather-resistant exterior wall envelope.

Interior Wall Coverings

Interior coverings and finishes must be installed as required by the code which outlines the minimum thickness for plaster, gypsum plaster proportions, maximum volume aggregate per volume of cementitious material for Portland cement plaster, and minimum thickness for gypsum drywall. Interior finishes and materials must comply with the flame spread and smoke-development requirements which state that wall and ceiling finishes shall have a flame-spread classification of no greater than 200 and a smoke-developed index of no greater than 450.

Minimum Room Dimensions

The total area of a residence is generally not regulated by code; however, a structure more than three stories in height would have to meet the provisions of the Florida Building Code- Building, rather than the Florida Residential Code. Only homes three stories or less, with a separate means of egress for accessory structures (like a garage or carport) fall under the provisions of the Residential Code. The Code does, however, have several minimum requirements that apply to residences. Residential space standards provide specifications for the internal floor area of dwellings and rooms.

Every dwelling must have at least one habitable room that has a minimum of 120 square feet of gross floor area. In most cases, this larger room is designed as the living area in a home. Other habitable rooms must have a floor area of at least 70 square feet and cannot have any one wall less than 7 feet in length.

The kitchen, however, though still considered a habitable room, can be a little smaller, but not less than 50 square feet in gross floor area. A habitable room is defined as all rooms used for living, dining, sleeping and cooking purposes. Bathrooms, closets, halls, and utility spaces are not considered habitable rooms.

When figuring the square footage of a room, any portions of the room with a sloped ceiling measuring less than 5 feet or a furred ceiling measuring less than 7 feet from the finished floor to the finished ceiling are not included as habitable space for the room.

The home designer has the flexibility to distribute the total amount of space among the rooms as they wish, as long as the combined spaces and the individual rooms meet minimum code requirements.

Ceiling Heights and Insulation

Habitable space, hallways, bathrooms, toilet rooms, laundry rooms, and portions of basements containing these spaces cannot have a ceiling less than 7 feet.
There are some exceptions to that provision:

1. Rooms with sloped ceilings need to have a ceiling height of at least 7 feet in no less than 50% of the required floor area of the room, and no portion of the required floor area can have a ceiling height of less than 5 feet.
2. The ceiling in a bathroom must be at least 6 feet 8 inches over bathroom fixtures as well as at the center of the clearance area in front of the fixtures, which ranges from 21” to 24” depending on the fixture type. In a shower or tub area with a shower head, there are minimum space requirements, which include a 30 inch x 30 inch area at the shower head and a ceiling height of no less than 6 feet 8 inches.

The code further specifies that ceilings in basements without habitable space, hallways, bathrooms, toilet rooms and laundry rooms can be as low as 6 feet 8 inches in height, and beams, ducts, or other obstructions may project to within 6 feet 4 inches of the finished floor.

Often people renovate an attic to increase their home’s resale value but spaces with a ceiling height of less than 7 feet don’t contribute to a home’s square footage in terms of appraisal.

Insulation materials must have a flame spread index not to exceed 25 with an accompanying smoke-developed index not to exceed 450.

Garages

The relationship between the garage and the habitable spaces of the home, require special attention and detailing. In order to prevent carbon monoxide or fumes from other hazardous materials stored in the garage from entering the house, openings from the garage leading directly into a bedroom space are not permitted by the Florida Building Code. Other openings between the garage and residence shall be equipped with either a solid wood door, solid, or honeycomb core steel door, none of which can be less than 1 3/8” thick, or you can use a 20-minute fire-rated door. The garage must be separated from the home interior and attic area by a minimum of ½” thick gypsum board applied to the garage side.

Garages situated beneath habitable rooms require a separation of at least 5/8” Type X gypsum board or equivalent.

There are two types of gypsum wallboard, regular and type X. Type X wallboard is formulated by adding noncombustible fibers to the gypsum. These fibers help maintain the integrity of the core as shrinkage occurs, providing greater resistance to heat transfer during fire exposure. Type X gypsum is typically required to achieve required fire resistance ratings.

Detached Garages and Carports:

Detached garages on the same lot as a house but located less than 3 feet away from it, require at least ½” gypsum board applied to the interior side of exterior wall that faces the home, this extra protection is not required on the garage walls perpendicular to the house.

There should be no opening for air duct systems into the garage, such as returns or vents. These might actually “fuel” a fire. Any ducts passing through the garage or penetrating the separating wall or ceiling are required to be a minimum of 26-gauge sheet steel, 1 inch minimum rigid nonmetallic Class 0 or Class 1 duct board, or other approved material.

Garage floors are required to be of an approved noncombustible material, and should be sloped to facilitate the movement of liquids either to a drain or toward the main vehicle entry.

Carports need to be open on at least two sides, and have approved noncombustible floor material. Ground level carports can have asphalt surfaces. If a carport is not open on at least two sides, it’s considered to be a garage according to code, and must meet the minimum provisions for garages.