Light Wood Frame Construction Chapter 5 Light Wood Frame Construction

Light Wood Framing Advantages Disadvantages Flexible Easily constructed Economical Disadvantages Burns rapidly, Decays if exposed to moisture Changes volume with moisture changes Framing unattractive (must be covered) Advantages Flexible MOST ANY SHAPE ASSIMILATED ALL THE CHANGES - MPE Easily constructed MINIMAL EQUIPMENT & TOOLS Economical STILL COMPETITIVE WITH “FACTORY BUILT” Disadvantages Burns rapidly, Decays if exposed to moisture Changes volume with moisture changes NATURAL PRODUCT - HUMIDITY AFFECTS

History - Prior to mid-1800s Timber Frame timber with masonry timber with earth fill Interior walls were simple plank structure Trees were plentiful, and labor was intense. Craftsmen were available, but tools were limited – and had to be operated by hand.

History - mid 1800s Light wood framing advanced by Development of water powered saw mills Machine made nails became available Earliest Version of Lt. Wood Framing Balloon Framing Long lengths of material was plentiful Wood members were small & easily handled Provided for lateral stability

Balloon Framing Erection of wall framing members on a wood sill secured to the foundation and lapped against the floor joists. Second floor joists lapped into the wall framing system. Roof framing then set on top of wall plates. Roof rafters tied to ceiling joists secured lateral displacement of exterior walls. Components were light in comparison to timber structures, and erection required minimal labor than before. The practice was a more efficient use of material.

DISADVANTAGES OF BALOON FRAMING Long, straight lengths of material diminished in availability as more structures were built. When buildings caught fire, the wall cavity of balloon framing allowed fire & smoke to chimney all the way to the roof, and structures burned rapidly. Since the wall and floor structure were built integrally, most of the framing work was done off the ground, where level conditions might not exist.

PLATFORM FRAMING With the disadvantages of balloon framing, the platform frame system evolved. The floor structure was first built onto the foundation sill, then decked to provide a ‘platform’ on which to work. Ground-floor walls were erected with a top plate to receive the second floor joists, which became a sill on which to erect the upper floor joists – which, when decked became another platform. Single floor framing was more plentiful because of shorter lengths.

Building Sequence Architect Plans and Designs the Facility – Then Prepares Design and Construction Documents Involve a selected Contractor, who: Obtains Building Permit Purchases necessary materials Selects Sub-Contractors for each phase of work Excavation for utilities, foundations Install Underground utility lines (electrical, plumbing) Foundation construction Floor Construction Erect Framing for Structure

Build construction pad & set batter boards

Batter boards enable accurate layout of foundation

A transit ensures accurate angles in layout

A level is used to ensure proper grades & elevation

Excavate & Place Foundations Materials Typically Used: Site Cast Concrete Concrete Masonry Units Reinforcing Steel Tie wire Anchor Bolts Foundation and Basement Wall Construction Construction for support of loads Damp proofing and/or perimeter insulation

Foundation Wall Systems Sill Anchor Concrete or CMU Wall Damp-proofing Drainage Stone under floor slab with Vapor Barrier Gravel for Drainage Perforated Drainage Pipe Concrete grade beam

Utility installation is simultaneous with foundation work

Installation of Plumbing Drainage Piping Underground Plumbing

Example of grade beam monolithic with concrete floor Wall Load Granular Base Thickened Slab on grade

Installation of plastic vapor barrier under concrete floor Granular SubBase

Foundation Insulation Some building codes require perimeter insulation at foundations – especially in cold climates. Insulate the Crawl Space or Basement Walls Attach to Platform or on Ground Vapor Barrier

Building the Platform Frame in Wood Floor With Crawl Space Sequence of Assembly Install sills with insect barriers Bolt sill members to the Foundation Install floor framing and bridging Install floor decking

Attachment to the Foundation Sill Material Treated for resistance to insects & decay in damp climates. Install insect shields Sill Attachment with anchor bolts

Floor Framing Options FRAME WITH FRAME FLOORS DIMENSION LUMBER USING TRUSSES

FRAME FLOORS WITH “I” JOISTS

Floor Framing Spacing & Splicing Factors that determine joist spacing: Floor Loading & Span Length Strength of Joist Material Used Type & thickness of floor decking Designation - Inches “o.c.” (on center) Typical - 12” , 16”, or 24” – to fit standard lumber lengths)

Bridging for Floor Framing

Floor Framing Using Steel Anchors

Decking over Floor Framing Materials Used Plywood or OSB Concrete or gypsum is poured over second floor decks for sound deadening Installation Deck is laid perpendicular to floor joists End joints are staggered to brace joists Power nails, screws, construction adhesive

Building Sequence for Ground Floor Walls Layout Sole plates installed to define wall locations Wall Framing - Lay out studs & assemble with single top wall plate Tilt up walls on the Platform & fasten to sole plate Install second layer of top wall plate to tie all partitions and walls together. Install Wall Sheathing Corner bracing required for lateral stability – usually OSB or plywood at all exterior corners

Framing Terminology Top Plate - Doubled Stud Header Sheathing Decking Sole Plate

Headers Headers are beams installed over openings to carry weight of second floor or roof loads. Sizing Factors: Load, Span, Material Materials: dimension lumber, Laminated wood, or Steel

Erecting the Wall Framing Build framing on the Platform & Tilt-up, brace, and fasten to sole plates.

Double Top Plate Joist Support Tie Framing Together

Double Top Plate Double Header Header Supports

Corner Framing

Sole Plate Anchorage

PROVIDES THE STURCTURAL STABILITY NEED DIAGONAL BRACING W/O SHEATHING Wall Sheathing Materials: OSB or Plywood for corner bracing Insulating Sheathing - (no structural qualities) PROVIDES THE STURCTURAL STABILITY NEED DIAGONAL BRACING W/O SHEATHING

Exterior Wall Sheathing: Joins & stabilizes the structure Resists uplift Resists racking & lateral forces Provides surface for finish material

Building Sequence PLATFORM & 2ND Story Walls Erect 2nd Story Platform Similar to 1st Floor Sequence Install 2nd Floor access (stairs) Erect 2nd Story Walls & Sheathing

Building Sequence Attic Floor & Roof Options Build-in-place ceiling joists, rafters, and bracing, OR Prefabricated Trusses, OR Combination

Roof Framing Built-in-Place Ridge Board Rafters

Collar Ties

LOOKOUTS TO FORM OVERHANGS GABLE FRAMING

Prefabricated Roof Trusses

Note Strand Orientation Hurricane Clip

Metal clips in decking prevent uneven deflection

Roof Profiles Flat Roof Single Pitch

Roof Profiles Gable Roof Hip Roof Hip Ridge