Wood Flashcards
<p>Structural/rough carpentry includes</p>
<p>structural framing, sheathing, blocking, anything to prep for finish work</p>
<p>Wood/lumber/timber</p>
<p>wood = comes from treeslumber = product of sawing, planing, etc.timber = at least 5 in. min. section</p>
<p>Adv./Disadv. of lumber</p>
<p>good: low cost, low footprint, easy to work, good insulator</p>
<p>bad: non-uniform, low strength, susceptible to moisture</p>
<p>Softwood vs. hardwood</p>
<p>soft: conifers (used for rough)</p>
<p>hard: deciduous (used for finish)</p>
<p>Lumber strength</p>
<p>depends on grain direction relative to load; best when load and grain parallel (eg., load on wood column); worst in bending</p>
<p>Lumber defects</p>
<p>knots (branch/limb), checks (growth rings are separated, pulled apart), pitch pocket (same as check, but filled w resin), shake (like check, but lengthwise instead of across grain), split (like check, but goes through piece of lumber, often at ends), wane (where bark was, or where chunk is just gone, usu. at corners)</p>
<p>warping: out of plane; bow warp - parallel, crook warp - side to side, cup = along width</p>
<p>Lumber grades</p>
<p>made by American Lumber Standards Committee; yard lumber: for structural/rough; factory/shop lumber: for finishing</p>
<p>Yard lumber</p>
<p>boards (less than 2), dimension (2 to 5), timber (more than 5)</p>
<p>2x2s, 2x4s (subdivided), 2x6s+</p>
<p>beams/stringers: 5" wide, 2"+ depth</p>
<p>posts/timbers: 5x5, depth not more than 2" than width</p>
<p>Factory lumber</p>
<p>grade B/better (best), C/select, D/select</p>
<p>common grades:Âno.1-no.5 (1 = best, usu. based on knots)</p>
<p>Nominal/Actual dimensions</p>
<p>1"=.75"</p>
<p>2-6=2.5-6.5</p>
<p>8-12=7.25-11.25</p>
<p>Moisture content</p>
<p>expressed as fraction of the overall weight of oven-dried wood; 30% = fiber saturation = when no water in cell cavities, but cell walls saturated = pt. when shrinkage starts to occur</p>
<p>Wood seasoning</p>
<p>Putting lumber on site, so it has time to shrink/swell to local/prevailing moisture content levels</p>
<p>Dry lumber</p>
<p>moisture content below 19% (req'd for structural lumber design values)</p>
<p>kiln dry = below 15%</p>
<p>Wood shrinking/swelling</p>
<p>occurs most perpendicular to grain, very little parallel to grain, most tangentially to growth rings, half as much radially</p>
<p>Wood stud construction</p>
<p>aka light frame wood construction, 2x4s or 2x6s, with a few heavier beams of built-up/heavy timber/steel members; can be platform (easier to construct)Âor balloon framing (less vertical shrinkage, stays parallel to wood grain)</p>
<p>Wood to masonry wall</p>
<p>hung by wood ledger + metal joistÂhanger or use fire cut (to prevent masonryÂfrom being pushed up/out when beam burns out)</p>
<p>Plywood ratings</p>
<p>thin wood veneer sheets glued together, usu. 4'x8', in .25"-.75" thickness, graded by span (measures stiffness/strength of parallel to face grain - eg 32/24, max dist. roof supports/max dist. floor supports, average residential conditions), also graded by wood species (I = group I woods, II = woods 2, 3, 4), graded by quality of face veneer (N natural finish, heartwood/sapwood, free of defects, A, B plugged knotholes, C small knothole/splits, D large knotholes); can have special glues/finishes for tough environments</p>
<p>Types of plywood</p>
<p>sheathing = attached to framing to provide structural support</p>
<p>particleboard = small wood particle/fibers/chips (low/med/high density), mostly for backing</p>
<p>OSB = oriented strand board - precision cut wood strands of 4" length, .0027" thick, layered at right angles, comes in bigger panels, subject to delamn.</p>
<p>MDF = medium density fiberboard - fibers made by steaming wood, most dimensionally stable panels, smooth face for finishing</p>
<p>hardboard = inter-felted fibers, can be tempered for hardness</p>
<p>Blocking, bridging</p>
<p>blocking = pcs btwn framing for rigidity or nail base</p>
<p>bridging = bracing btwn joists to prevent joist buckling (can be wd blocking or metal cross braces), usu 8' + o.c.</p>
<p>firestops = barriers in concealed framing spaces, can be 2"+ wood, gypsum, mineral wool</p>
<p>Engineered wood</p>
<p>smaller/waste woods to make stonger, bigger members; glue/metal fasteners/insulationÂused; includes plywood web joists (TJIs) (less wasteful, stronger, less shrinkage), laminated veneer lumber/structural composite lumber (thin lams parallel to length), trusses, SIPs panels, composite decking, CLTs cross-laminated timbers, glulams</p>
<p>Wood truss types</p>
<p>king post, queen post, Fink, scissor, Warren, Howe Pratt</p>
<p>SIPs</p>
<p>structural insulated panels: usu. OSB + EPS (expanded polystyrene)</p>
<p>other facings: plywood, Al panels, cement board, gypsum wallboard</p>
<p>other insulation: extruded polystyrene (XPS), urethane foam, compressed straw</p>
<p>thicknesses btwn 4.5"-12.25", usu. 4'x8' to 9'x28'</p>
<p>reduce construction time, improved insulation values bc reduced air infiltration, higher strength, flatter surfaces, dimensional stability</p>
<p>problems w/seismic anchoring, vapor barrier placement, insect damage</p>
<p>Composite wood decking</p>
<p>wood-plastic composite - planks formed from ~50%Âsm. wood fibers or wood flour mixed w ~50%Âplastic (polyethylene), along w/ colorants, stabilizers, fungicides</p>
<p>lasts longer than dimensioned lumber, stronger, splinter-free, recycled materials</p>
<p>hotter underfoot, warp prone</p>
<p>Cross-laminated timber</p>
<p>CLT, layer dimensioned lumber at right angles to make panel, very strong, resist bending, racking, act as strong diaphragm, can use smaller diameter trees since acting togther (green)</p>
<p>Heavy timber construction</p>
<p>Main framing members of bldg from large dimensioned wood or engineered wood</p>
<p>Glulams</p>
<p>Glue-laminated wood members; depths are multiples of 1.5" (2xs), higher allowable stresses bc members defect free, dried, etc.; specified by stress rating; grades are industrial (rough), architectural (medium), premium (finest)</p>
<p>Wood decking</p>
<p>aka planking, solid or lam timber spanning btwn beams, usu. TNG, spans more than sheathing (4'-20'), can be both structural & finish floor/ceiling (but hard to conceal insul, services</p>
<p>= heavy tiber constr.!</p>
<p>Wood fasteners</p>
<p>nails (weakest, most common - box, common wire, wire spikes), screws (flat/round head, threading makes stronger cnxn, lead holes make stronger, lag = pointed end but head like bolt), bolts (use washer at head to distribute load), metal fasteners (lightweight connectors, timber conn., split rings, shear plates to transfer loads, gang nail plates),Âetc.</p>
<p>use nailing schedule for size, number, spacing, penetration type</p>
<p>Wood treatments</p>
<p>preservatives brushed, dipped or pressure applied to fight moisture + insects</p>
<p>creosote (coal tar, water proof, RR ties, marine structr.), oil-borne (penta/pentachlorophenol, for utility poles, pilings, bridges, long spans over swimming pools), water-borne (ACQ/ammoniacal copper quaternary, sodium borate/SBX, etc., lesser VOCs, paintable, but don't use w Al bc corrosive); treat all cuts w 2% copper in copper naphthenate</p>
<p>no longer used: CCA/chromated copper arsenate, ACZA/ammoniacal copper zinc arsenate bc of arsenic content, but were less corrosive</p>
<p>Finish carpentry includes</p>
<p>factory finished items like finished cabinetry &Âshelving, wall paneling, custom doors; also exterior siding, interior trim, stair framing, door &Âwindow framing</p>