b'THE OFFICIAL NFBA MAGAZINEcontinued from page: 13The second floor system will need to be designed to satisfy the strength and deflection requirements of the IBC.The span of the floor system will determine if any of the interior walls will need to be used as bearing walls. In post-frame buildings, the second floor framing consists generally of dimensionallumberormanufacturedjoists (i-joists, floor trusses), dimensional lumber, glulam or laminated veneer lumber (LVL) beams, RESEARCH & TECHNOLOGYand dimensional lumber or LVL ledgers.The beams are supported by posts or interior walls on a thickened concrete slab, spread footings below Post and truss spacing will vary, with larger trussthe slab, or a round shallow post foundation. spacings more common in the mid-western partsThe design of wood framing and connections is of the country. 8 o/c posts is a pretty typical postgoverned by the National Design Specification frame design standard. For some, the preference isfor Wood Construction (NDS). to have the truss spacing match the post spacing,The loading on the floor framing is determined so that no additional headers are needed to carryby the intended use of the space. Residential live intermediate trusses, however there are multipleload requirements can be separated into habitable factors to consider when deciding this. Withsleeping areas and all other areas. larger truss spacings, some interior finishes willThe climate zone will determine the insulation require additional framing. Bracing and roofrequirements for the building. Post frame walls purlin configurations are different with largerprovide deep wall cavities with fewer breaks in the truss spacings as well. The trusses themselvesthermal insulation barrier because of the greater may need to be multi-ply or consist of higherpost spacing. Because of this, post frame buildings grade or larger members.The truss manufacturercan actually exceed the minimum insulation will provide the engineered truss design, whichrequirements. ResCheck software can be used to the design professional will incorporate into thedetermine the building envelope compliance, or building design. 4 o/c roof trusses with headers tothe prescriptive method can be used by meeting carry the intermediate trusses may end up beingthe values for each building component listed in just as efficient as the larger truss spacings. Roofthe tables in the energy code.pitch and span of the trusses are both factors that will impact the truss design as well.There are fire protection and life safety requirements The post frame shell of a barndominium allowsthat apply to barndominiums, similar to other for a second floor to be easily incorporated intobuildings. Proximity to the lot line will determine the building. The outside perimeter of the secondif the exterior wall of the barndominium will need floor framing can be supported by the side andto be fire-resistance rated. If the distance between end wall columns.The most common detail forthe building and the lot line is less than five feet, this type of support includes a single or doubleda 1-hour fire resistant rating with exposure from ledger board fastened to the wood columns withboth sides is required. There are UL-approved nails or structural screws.A support below thefire-resistance rated post frame wall assemblies ledger may be required if the ledger cannot fit theto meet 1,2, and 3-hour rating requirements. required quantity of fasteners.The floor joists areSeparation of the dwelling area from the garage attached to the ledger board with joist hangers. per Table R302.6 is required. This table does not provide an hourly rating requirement like the continued on page: 1514 / FRAME BUILDER - VOL6 1'