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Trinity Timber Case Studies slideshare


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Trinity Timber Case Studies slideshare

  1. 1. Timberwork Case Studies MSc. Building Conservation 22 February 2013
  2. 2. Paul PriceWoodwrights Oak frame carpentry and timberconservation
  3. 3. An overview of historiccarpentry and timber repair Topics: 1.Recognising historic carpentry 2.Repairs: surveys and methods 3.Case histories
  4. 4. Historic timberwork Part of our built heritage – in Ireland: especially roofs. A valuable record of historic craftwork - timber conversion and scribe carpentry.Christchurch Cathedral, Dublin. 17th C. oakwork
  5. 5. Ilustrations from:McCracken, E. (1971) The Irish Woods Since Tudor Times
  6. 6. Holy Trinity Church,Fethard, Co. Tipperary Medieval oak roof frame, discovered 2010
  7. 7. See-sawing (swivel or trestle sawn)
  8. 8. Timber Conservation Aims Conserve the overall aesthetic form of the structural frame while repairing the structure. Preserve original timber as much as possible. Timber surfaces, which preserve marks recording the original timber conversion and framing methods.Dunsoghley Castle, Co. Dublin.High quality scribe carpentry;Double collar;Arch-braces with locking tenons;Scribe numbers visible.
  9. 9. Timber Conservation Process Survey: historical value, condition, and structure. Repairs: minimal, unobtrusive, reversible. Outlook: maintenance check-listNorway - Loft repair.Timber replacement:New timber selected,cleft and hand hewnto match originaldecayed element.
  10. 10. Recognising historic carpentryConversion: logs into timberCarpentry: scribing, jointing and raising frames
  11. 11. Oak - tough and durable.Baltic pine – imported. Two forms of historic timberwork: Treewrightingaxe-hewn, boxed heart, often smaller ‘stuff’, cottage roofs; Frame carpentry hewn plus rip-sawn, mortice and tenon,large range of scantlings, use of grown “bends”, larger, more durable buildings.
  12. 12. Hewing: Turning logs into timber. Marking and notching
  13. 13. Juggling HewingNotching Finishing with broadaxe
  14. 14. Hewing:Finishing- A broadaxe was used to give a flat finish
  15. 15. Close up ofhewn surfaceAxe nick marks Stop mark Note mutualangle of marks
  16. 16. Pit-sawnsurface withframers’ level mark
  17. 17. Scribing: Timber placed over full scale layout so thatjoints can be scribed to allow accurate fit of irregular timbers
  18. 18. Reference linePlumb bob
  19. 19. Scribedshoulder
  20. 20. Scribe carpentry workshop
  21. 21. Numbering: Usually Roman - chiselled or race-knifed
  22. 22. Recognising historic timberwork Hewn or pit-sawn surfaces Carpenters layout marks - scribe lines and references Mortice and tenon joints Chiselled numbers at jointsScribed joints - shoulders scribed to match irregularities
  23. 23. Repairs:surveys and methods
  24. 24. Surveys Record DrawingsBasic survey - Schematic timber drawings and photographs. Full Survey: Archeological level recording. EstimatingAnnotate basic survey schematics with current condition and possible repairs
  25. 25. Bishops Palace, Salisbury,Wiltshire, EnglandRoof by Francis Price 1726 Our repairs 1998
  26. 26. Cathedral Church, Cashel Nave roof 1780 Large span 46ft =14mTransition carpentry Diagnosing astructural problem. – Is it really a problem?
  27. 27. Cashel Cathedral Church Roof: • Queen post roof with king strut • Ceiling load has deformed roof
  28. 28. Joint separation 100mm+
  29. 29. Cashel:Structural Originalschematic Current Movement appears locked but should be monitored
  30. 30. Repair Methods
  31. 31. Repair Methods for Historic Timberwork •Steelwork: straps, flitch plates, cables, brackets, bolts, screws to secure joints and framing. •Carpentry: replacement timbers, patch and end repairs. •Resin: consolidation, packing, patch and end repairs. Beware the “honest” repairMaking repairs look distinctive from original work is often an excuse for unsightly repairs.
  32. 32. METAL REPAIRS:•Often cheapest and best if hidden or subtle- no disassembly needed•Reversible and easier. Unsightly if visible and poorly designed.•Use galvanised or stainless steel for repairs.
  33. 33. CARPENTRY REPAIRS•Potentially damagingdisassembly required forreplacement or endrepairs.•Requires high qualityrepair carpentry for goodresults.•Decide whether to matchconversion methods.•Use oak with oak etc.
  34. 34. End repairs• require carefulfitting andassembly• use dry timberwhere possible.• may have to usegreen -allow forshrinkage andlater tightening
  35. 35. New tenon repair - only possible if frame elements disassembled
  36. 36. Multiple scarf repairs to softwood wall
  37. 37. Rafter notch joint reformed in resinRESIN REPAIRS:•Good for consolidating valuable decayed timber and for packingout steel repairs.•Bad for large end repairs. Can be very ugly.•Always use resin designed specifically for structural timber work.
  38. 38. Timber durability: Excellent if kept dry. Good if sheltered. Bad if continually damp.Exposed to weather for 600 years Leaking weathervane - king post decayed
  39. 39. Case Histories
  40. 40. Barn, Co. Wicklow An exceptional and18th Century unusual barn frame
  41. 41. Barn in WicklowShipping marks on Baltic Pine on hewn surfaces.Race knifed symbols denoting timber baulkquality and quantity.
  42. 42. Unusual framed cantilevered roof overhang
  43. 43. Bridled scarf withsallied abutments in a10 cm by 6.5 cmtimber !!
  44. 44. Dragon tie hip assembly: Note numbering
  45. 45. Purlins scribed over hip bevel
  46. 46. Curved End New tie and reassembly numbers
  47. 47. Historic pine: Left side has been sandblasted.Note serious loss of fragile but intact surface.
  48. 48. Winchester Cathedral,South TransceptDendro date 1313Difficult working conditionsLaminated in-situ repairs
  49. 49. Disassembly: can see inside joints•Soulace brace with locking tenon•Axed tenon faces•Drawbored tenon•Centre lines
  50. 50. Southwick Barn. Hampshire, EnglandCollapsing barn- uprighted, mostly in-situ steel repairs
  51. 51. Gusset bracket and flitch repairs
  52. 52. Wooton Bassett,Wiltshire, EnglandDecay of 19th centuryoak repairs due toimpermeable blackpaint
  53. 53. Repaired frame prior to stripping impermeable paint Frame and replastered panels then limewashed
  54. 54. House at Laxfield, Suffolkworking with TraditionalOak Carpentry Co
  55. 55. Structural frame repairs - support carefully!
  56. 56. Cill plate decay - due to constant wetting,impermable paint, and cement mortar/render.
  57. 57. Exterior new timberconserving interior -Coach screwed togetherwith resin packing
  58. 58. Installing new cill withnew and repaired timber
  59. 59. Frame reassembled with new plinth built up. Exterior frame aesthetic conserved.
  60. 60. Decay treatment
  61. 61. Interior timberentirely saved.Poor quality offraming timber-hedgerow stuff
  62. 62. Charlton Court Barn, West Sussex, EnglandDendro-datedto 1404Major repairs•Roof stone removed, frame realigned, joints reassembled•Very costly - steel building over, detailed repairs throughout.Use for special buildings.
  63. 63. Patch repair: coach End repairs:screwed and plugged Tabled stop splay scarf
  64. 64. New timbers where missing•Re-make in new timber onpattern of existing.•Better than unsightlyexposed steel.•Can make decision tomatch existing conversionto similar pieces. New aisle sway brace
  65. 65. Purlin span decreased using in-line steel angles - no plywood
  66. 66. Completed frame repair•Aesthetic conserved•Structure repaired
  67. 67. An overview of historiccarpentry and timber repair Topics: •Recognising historic carpentry •Repair surveys and methods •Case histories
  68. 68. Thank-you Paul