Timber, framing and constructions - mjobrien

1 1 Timber, framing andconstructionsReferences: Building with Wood by Rempel Building the Timber Frame House by BensonHeavy TimberWhen exposed to fire, heavy timberdevelops a charcoal layer at the rate ofabout 1/40th of an inch deep per minute offire charcoal is actually burnt wood, actingas an insulator to slow down theconsumption of the wood the wood continued to burn at 1/40 thinch per minute, 1 inch burns in 40minutes, 2 inches in 80, and 3 inches - theburn-through point would take up to 120minutes - TWO HOURS2It s considered Heavy The minimum sizes 6 x 8 for a column supporting a roof 8 x 8 for a column supporting a floor 6 x 10 for a floor beam 8 x 8 for a roof truss member 4 x 6 for a roof beam 3 + 1 finish floor decking 2 roof decking.

2 According to the building codeSome additional fine print No concealed spaces between ceiling and floor, inwalls, and roof. Stair treads & risers, made of 2 thick material Finished floors stop 1/2 short of exterior walls. Wood bearing partitions cannot support more than 2floors and roof Built up members must be min. 3 thick3 Code BonusArea per floorHeight(feet)Type IAType IBType IIAType IIBType IIIAType IIIBType IVHTType VAType VBGroupH / AUL160 65 55 65 55 65 50 40 A1 HUL53232321 AULUL15,5008,50014,0008,50015,00011,5005 ,500 BHUL115454532 AULUL37,50023,00028,50019,00036,00018,00 09,000 Even as combustible construction, the code recognizes that timber framedbuildings afford occupants more time to evacuate, and firefighters more timeto fight a fire because the massive members don t burn through and failnearly as quickly as lightwood (stud) framing members.

3 Due to this slow burn through (a function of the charring acting asinsulation) the code gives type IV HT construction an additional two floors inheight and twice the square footage than a type V-a construction type for a B did Timberconstruction start? No one knows. Pit dwellings from 1000 AD havebeen found on the North Americanand European continents. Pit dwellings were simpleconstructions where the earth wasshaped for protection, fallen trees orlimbs lashed together to formoverhead structure, and skins orvegetation placed over the structureto form Cruck frames were adevelopment of the pithouse. Curved tree trunkswere leaned together andlashed / joined to wall androof framing to provide somelateral bracing.

4 The shortage of curved treesbegan to limit the spread ofthese frames acrossEngland and braces The braced frame wasthe next development oftimber following thecruck. It used curvedbraces between theverticals and horizontalsto provide heavy skeletonGround SillCorner PrincipalsSummer BeamPostsStudsBracesBeamsJoistsPrincipal RaftersKingPost6x6 StudsA common form of timber framing for smaller structures was to framethe walls with vertical members, raise it, then add roof members toenclose. An early form of the stud much at this close spacing have an impressive structural capacity,which goes mostly This braced frame is thebasis for mosttraditional timber framesconstructed today.

5 The frames are notassembled in place onepiece at a time, butrather as siteprefabricated structuralassemblies The bent is pre-assembled on theground, and with somepeople lifting, somepushing pike poles, andsome pulling with ropes,the bent would be raisedinto for Timber Framing8 Jobs for all agesDue to the weight of the members and the special skills neededto layout and cut the joints, frame raisings could employ theolder, more skilled, as well as the younger, stronger refinementThese floor framing members have only been hewed flat on thetop side, the bottom still has bark on it. It took so much labor torefine the logs into building components that only those surfacesabsolutely needing refinement were itself was done with a crew on one side of thebent pulling, and a crew on the other side pushingwith pike poles.

6 The foreman had to keep balancebetween the crews to prevent the bent from beingpulled or pushed over onto the opposing between the bents are filled in with joists andpurlins to carry the roof shingles10 The completed frame is a community achievement11 Timber framing in our timePower tools have made thecomponents for the timberframe easier to refine, but themethods for joining andprinciples of construction arelargely unchanged from the1600 sHere a timberwright lays out aknee brace to be inserted in amortise cut in the column andbeam to give the bentadditional lateral complete, the frame is laterally braced in both axisby the knee braces between the columns and the frame requiresSaws for cutting off thetrunnelsRubber bandsSledge hammers &The beetle or commander (the really big hammer)These housed dovetail purlins are stockpiled on the site.

7 They will be thepieces that drop into the bents to tie the frame together at the mortise and tenon connectionis the most common type of jointfound in the timber of nails or screws, trunnels(tree nails) are used to join the twomembers the tenon is cut shorterthan the mortise (to allow for crossgrain shrinkage)And the holes for the mortise andtenon don t line up! (a drawbore)They are offset by an 1/8 inch orso to pull the tenon tight into themorise (the drawbore draws themortise into the tenon)..and keepit mortise and tenon joint is shouldered (the vertical isnotched to receive the horizontal)Shouldering puts the full depth of the beam to workresisting the tenon doesn t have to do all thework14 This mortise and tenonis located at the pointwhere the roof membermeets the column.

8 Thesingle trunnel is allthat s needed as mostof the load puts the roofmember , it s common tofind the frame beingraised by a craneinstead of pike polesand (fewersquished timberframers!)The last bent is beingpositioned, it will be heldin place by the secondfloor beam at a mortise& tenon joint, and by theroof purlins, which use adropped in type ofhoused Even with the crane, the crew struggles to fit the tenoned end ofthe beam into the mortise cut in the bent. That last bent istemporarily tilted away from the frame and braced until all themortise and tenon joints are partially fitted. Then the last bent willbe pulled into vertical with portable winches called come alongs The come alongs areconnected to the frame withstrips of inner tube to keep thesteel cable from scarring are partially fitted, andwill be driven home with trunnelshome with amallet come along Once the trunnels are driven home any projectingtrunnel is cut off with a completed frame is sanded and oiled like a finepiece of is the traditional time for the post-frame I think here it was preserve the presence of the frame on the interior panels that areboth sheathing, insulation and drywall are spiked to the frame.