Fire-retardant-treated wood (FRTW) is any wood product which, when impregnated with chemicals by a pressure process or other means during manufacture, shall have, when tested in accordance with ASTM E 84 or UL 723, a listed flame spread index of 25 or less and shows no evidence of significant progressive combustion when the test is continued for an additional 20-minute period. In addition, the flame front shall not progress more than 10.5 feet (3200 mm) beyond the center line of the burners at any time during the test.R802.1.3.1 Pressure process.
For wood products impregnated with chemicals by a pressure process, the process shall be performed in closed vessels under pressures not less than 50 pounds per square inch gauge (psig) (344.7 kPa). R802.1.3.2 Other means during manufacture.
For wood products produced by other means during manufacture the treatment shall be an integral part of the manufacturing process of the wood product. The treatment shall provide permanent protection to all surfaces of the wood product. R802.1.3.3 Testing.
For wood products produced by other means during manufacture, other than a pressure process, all sides of the wood product shall be tested in accordance with and produce the results required in Section R802.1.3. Testing of only the front and back faces of wood structural panels shall be permitted. R802.1.3.4 Labeling.
Fire-retardant-treated lumber and wood structural panels shall be labeled. The label shall contain:
- The identification mark of an approved agency in accordance with Section 1703.5 of the Florida Building Code, Building.
- Identification of the treating manufacturer.
- The name of the fire-retardant treatment.
- The species of wood treated.
- Flame spread index and smoke-developed index.
- Method of drying after treatment.
- Conformance to applicable standards in accordance with Sections R802.1.3.5 through R802.1.3.8.
- For FRTW exposed to weather, or a damp or wet location, the words "No increase in the listed classification when subjected to the Standard Rain Test" (ASTM D 2898).
Design values for untreated lumber and wood structural panels as specified in Section R802.1 shall be adjusted for fire-retardant-treated wood. Adjustments to design values shall be based upon an approved method of investigation which takes into consideration the effects of the anticipated temperature and humidity to which the fire-retardant-treated wood will be subjected, the type of treatment and redrying procedures. R802.1.3.5.1 Wood structural panels.
The effect of treatment and the method of redrying after treatment, and exposure to high temperatures and high humidities on the flexure properties of fire-retardant-treated softwood plywood shall be determined in accordance with ASTM D 5516. The test data developed by ASTM D 5516 shall be used to develop adjustment factors, maximum loads and spans, or both for untreated plywood design values in accordance with ASTM D 6305. Each manufacturer shall publish the allowable maximum loads and spans for service as floor and roof sheathing for their treatment. R802.1.3.5.2 Lumber.
For each species of wood treated, the effect of the treatment and the method of redrying after treatment and exposure to high temperatures and high humidities on the allowable design properties of fire-retardant-treated lumber shall be determined in accordance with ASTM D 5664. The test data developed by ASTM D 5664 shall be used to develop modification factors for use at or near room temperature and at elevated temperatures and humidity in accordance with ASTM D 6841. Each manufacturer shall publish the modification factors for service at temperatures of not less than 80°F (27°C) and for roof framing. The roof framing modification factors shall take into consideration the climatological location. R802.1.3.6 Exposure to weather.
Where fire-retardant-treated wood is exposed to weather or damp or wet locations, it shall be identified as "Exterior" to indicate there is no increase in the listed flame spread index as defined in Section R802.1.3 when subjected to ASTM D 2898. R802.1.3.7 Interior applications.
Interior fire-retardant-treated wood shall have a moisture content of not over 28 percent when tested in accordance with ASTM D 3201 procedures at 92 percent relative humidity. Interior fire-retardant-treated wood shall be tested in accordance with Section R802.1.3.5.1 or R802.1.3.5.2. Interior fire-retardant-treated wood designated as Type A shall be tested in accordance with the provisions of this section. R802.1.3.8 Moisture content.
Fire-retardant-treated wood shall be dried to a moisture content of 19 percent or less for lumber and 15 percent or less for wood structural panels before use. For wood kiln dried after treatment (KDAT) the kiln temperatures shall not exceed those used in kiln drying the lumber and plywood submitted for the tests described in Section R802.1.3.5.1 for plywood and R802.1.3.5.2 for lumber.
- Ultimate design wind speed, Vult, and exposure category.
- Slope or depth, span and spacing.
- Location of all joints.
- Required bearing widths.
- Design loads as applicable.
- Top chord live load (as determined from Section R301.6).
- Top chord dead load.
- Bottom chord live load.
- Bottom chord dead load.
- Concentrated loads and their points of application.
- Controlling wind and earthquake loads.
- Adjustments to lumber and joint connector design values for conditions of use.
- Each reaction force and direction.
- Joint connector type and description (e.g., size, thickness or gage) and the dimensioned location of each joint connector except where symmetrically located relative to the joint interface.
- Lumber size, species and grade for each member.
- Connection requirements for:
- Truss to girder-truss.
- Truss ply to ply.
- Field splices.
- Calculated deflection ratio and/or maximum description for live and total load.
- Maximum axial compression forces in the truss members to enable the building designer to design the size, connections and anchorage of the permanent continuous lateral bracing. Forces shall be shown on the truss design drawing or on supplemental documents.
- Required permanent truss member bracing location.
- For rafter connections to the top plate, straps and/or clips shall extend such that the top nail is within 1 inch (25.4 mm) of the top of the rafter with one or more nails installed on the opposite side of the rafter.
- Roof sheathing shall be at a minimum attached in accordance with Section R803.2.3.
Table R802.5.1(1) Rafter Spans For Common Lumber Species (Roof live load = 20 psf, ceiling not attached to rafters, L/Δ = 180).
Table R802.5.1(2) Rafter Spans For Common Lumber Species (Roof live load = 20 psf, ceiling attached to rafters, L/Δ = 240).
Table R802.5.1(3) Rafter Spans For Common Lumber Species (Ground snow load = 30 psf, ceiling not attached to rafters, L/Δ = 180).
Table R802.5.1(4) Rafter Spans For Common Lumber Species (Ground snow load = 50 psf, ceiling not attached to rafters, L/Δ = 180).
Table R802.5.1(5) Rafter Spans For Common Lumber Species (Ground snow load = 30 psf, ceiling attached to rafters, L/Δ = 240).
Table R802.5.1(6) Rafter Spans For Common Lumber Species (Ground snow load = 50 psf, ceiling attached to rafters, L/Δ = 240).
Table R802.5.1(7) Rafter Spans For 70 PSF Ground Snow Load (Ceiling not attached to rafters, L/Δ = 180).
Table R802.5.1(8) Rafter Spans For 70 PSF Ground Snow Load (Ceiling attached to rafters, L/Δ = 240).
Table R802.5.1(9) Rafter/Ceiling Joist Heel Joint Connections.
Figure R802.5.1 Braced Rafter Construction.
Table R802.11 Rafter or Truss Uplift Connection Forces from wind (Pounds per Connection).
Allowable spans for lumber used as roof sheathing shall conform to Table R803.1. Spaced lumber sheathing for wood shingle and shake roofing shall conform to the requirements of Sections R905.7 and R905.8. Spaced lumber sheathing is not allowed in Seismic Design Category D2.
MINIMUM THICKNESS OF LUMBER ROOF SHEATHING
|RAFTER OR BEAM SPACING |
|MINIMUM NET THICKNESS |
|48a||11/2 T & G|
- Minimum 270 Fb, 340,000 E.
- Minimum 420 Fb, 660,000 E.
- Minimum 600Fb, 1,150,000 E.
- 0.113 inch nominal root shank diameter
- Ring diameter of 0.010 over shank diameter
- 16 to 20 rings per inch
- 0.280 inch full round head diameter
- 2-3/8 inch nail length
- Where roof framing with a specific gravity, 0.42 ≤G < 0.49 is used, spacing of ring-shank fasteners shall be permitted at 12 inches (305 mm) on center at intermediate framing in nailing zone 1 for any Vult and in nailing zone 2 for Vult less than or equal to 140 mph in accordance with Figure R803.2.3.1.
- Where roof framing with a specific gravity, G =0.49 is used, spacing of ring-shank fasteners shall be permitted at 12 inches (305 mm) on center at intermediate framing in nailing zone 1 for any Vult and in nailing zone 2 for Vult less than or equal to 150 mph in accordance with Figure R803.2.3.1.
- Where roof framing with a specific gravity, G =0.49 is used, 8d common or 8d hot dipped galvanized box nails at 6 inches (152 mm) on center at edges and 6 inches (152 mm) on center at intermediate framing shall be permitted for Vult less than or equal to 130 mph in accordance with Figure R803.2.3.1.
- Where roof diaphragm requirements necessitate a closer fastener spacing.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow. Ventilation openings shall have a least dimension of 1/16 inch (1.6 mm) minimum and 1/4 inch (6.4 mm) maximum. Ventilation openings having a least dimension larger than 1/4 inch (6.4 mm) shall be provided with corrosion-resistant wire cloth screening, hardware cloth, or similar material with openings having a least dimension of 1/16 inch (1.6 mm) minimum and 1/4 inch (6.4 mm) maximum. Openings in roof framing members shall conform to the requirements of Section R802.1.8. Required ventilation openings shall open directly to the outside air.
The minimum net free ventilating area shall be 1/150 of the area of the vented space.
- In Climate Zones 6, 7 and 8, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.
- At least 40 percent and not more than 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located no more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically, with the balance of the required ventilation provided by eave or cornice vents. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted.
- The unvented attic space is completely contained within the building thermal envelope.
- No interior Class I vapor retarders are installed on the ceiling side (attic floor) of the unvented attic assembly or on the ceiling side of the unvented enclosed rafter assembly.
- Where wood shingles or shakes are used, a minimum 1/4-inch (6 mm) vented air space separates the shingles or shakes and the roofing underlayment above the structural sheathing.
- In Climate Zones 5, 6, 7 and 8 of Table R301.1 of the Florida Building Code, Energy Conservation, any air impermeable insulation shall be a Class II vapor retarder, or shall have a Class III vapor retarder coating or covering in direct contact with the underside of the insulation.
Either Items 5.1, 5.2 or 5.3 shall be met, depending on the air permeability of the insulation directly under the structural roof sheathing.
- Air-impermeable insulation only. Insulation shall be applied in direct contact with the underside of the structural roof sheathing.
- Air-permeable insulation only. In addition to the air-permeable insulation installed directly below the structural sheathing, rigid board or sheet insulation shall be installed directly above the structural roof sheathing as specified in Table R806.5 for condensation control.
- Air-impermeable and air-permeable insulation. The air-impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing as specified in Table R806.5 for condensation control. The air-permeable insulation shall be installed directly under the air-impermeable insulation.
- Where preformed insulation board is used as the air-impermeable insulation layer, it shall be sealed at the perimeter of each individual sheet interior surface to form a continuous layer.
|CLIMATE ZONE||MINIMUM RIGID BOARD ON AIR- |
IMPERMEABLE INSULATION R-VALUEa
|2B and 3B tile roof only||0 (none required)|
|1, 2A, 2B, 3A, 3B, 3C||R-5|
- Contributes to, but does not supersede, the requirements in Section R403.2.1 of the Florida Building Code, Energy Conservation.
Buildings with combustible ceiling or roof construction shall have an attic access opening to attic areas that exceed 30 square feet (2.8 m2) and have a vertical height of 30 inches (762 mm) or greater. The vertical height shall be measured from the top of the ceiling framing members to the underside of the roof framing members.
The rough-framed opening shall not be less than 22 inches by 30 inches (559 mm by 762 mm) and shall be located in a hallway or other readily accessible location. When located in a wall, the opening shall be a minimum of 22 inches wide by 30 inches high (559 mm wide by 762 mm high). When the access is located in a ceiling, minimum unobstructed headroom in the attic space shall be 30 inches (762 mm) at some point above the access measured vertically from the bottom of ceiling framing members. See Section M1305.1.3 for access requirements where mechanical equipment is located in attics.