Timber Houses and Buildings in New Zealand


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Timber Houses and Buildings in New Zealand
Presentation at CTT CORMA 14 May 2010
Graeme Beattie, Principal Structural Engineer, BRANZ

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Timber Houses and Buildings in New Zealand

  1. 1. Timber Houses and Buildings in New Zealand Graeme Beattie, Principal Structural Engineer, BRANZ (graeme.beattie@branz.co.nz) Presentation at CTT CORMA 14 May 2010
  2. 2. Timber Buildings <ul><li>Content of presentation </li></ul><ul><ul><li>Typical Timber Framed Houses </li></ul></ul><ul><ul><li>Materials and sizes </li></ul></ul><ul><ul><li>Building Standards/Regulations </li></ul></ul><ul><ul><li>House Design </li></ul></ul><ul><ul><li>Earthquake bracing </li></ul></ul><ul><ul><li>Large Timber Buildings </li></ul></ul>
  3. 3. Timber Framed Houses Older houses – before 1980
  4. 4. Timber Framed Houses New houses – since 1980
  5. 5. Timber Framed Houses
  6. 6. Timber Framed Houses Pressed metal roof tiles Brick as a cladding – not structural
  7. 7. <ul><li>Radiata pine or Douglas Fir </li></ul><ul><li>90mm x 45mm plates and studs at 400mm or 600mm centres </li></ul><ul><li>45mm thick joists up to 300mm deep or manufactured joists (I beams, LVL) </li></ul><ul><li>45mm thick trusses </li></ul>Typical Framing
  8. 8. Typical Timber Framing Truss Wall frame Timber floor
  9. 9. <ul><li>Building Act (of Parliament) – the Law </li></ul><ul><li>New Zealand Building Code Compliance </li></ul><ul><li>Building Standards </li></ul><ul><li>Specific design Non-specific design </li></ul><ul><li>(NZS3603 – Multistorey (NZS3604 - Houses) </li></ul><ul><li>Buildings) </li></ul>Regulations
  10. 10. <ul><li>Recipe book </li></ul><ul><li>Tells how to build a timber house </li></ul><ul><ul><li>Sizes, Spans, Bracing requirements, Fixings </li></ul></ul><ul><li>No engineer required </li></ul><ul><li>Maximum 2 storeys </li></ul><ul><li>www.standards.co.nz </li></ul>NZS 3604:1999
  11. 11. <ul><li>Bracing requirements determined by: </li></ul><ul><ul><li>Wind load </li></ul></ul><ul><ul><li>Earthquake load </li></ul></ul><ul><ul><li>Number of storeys (maximum 2) </li></ul></ul><ul><ul><li>Weight of roof </li></ul></ul><ul><ul><li>Weight of cladding </li></ul></ul><ul><ul><li>Soil must be “good” – min. 300kPa ULS bearing </li></ul></ul><ul><ul><li>Wall bracing usually by sheet/panel products on internal walls (and inside exterior wall) </li></ul></ul><ul><ul><ul><li>Tested to find bracing capacity (P21 test) </li></ul></ul></ul>NZS 3604:1999
  12. 12. Wall Bracing Test (BRANZ P21) Jack and loadcell Test Specimen (Drywall) Load Load is cyclic to increasing Displacements www.branz.co.nz
  13. 13. Example Hysteresis Loops
  14. 14. Wall Bracing Hold down Concrete Floor on ground 25mm x 1mm strap wrapped under plate and nailed to stud 12mm bolt and 50mm square washer
  15. 15. <ul><li>Proprietary hold down (Handibrac) </li></ul>Wall Bracing Hold down alternative Sheet Lining
  16. 16. <ul><li>Specific design (engineer involved) </li></ul><ul><li>Light timber framing (LTF) </li></ul><ul><ul><li>Apartments (many walls for bracing) </li></ul></ul><ul><ul><li>Must solve noise and fire issues </li></ul></ul><ul><li>Heavy sections </li></ul><ul><ul><li>Laminated Veneer Lumber (LVL) </li></ul></ul>Multistorey Timber Buildings
  17. 17. Multistorey LTF
  18. 18. Joints Between Tenancies Important to maintain continuity of floor diaphragm Floor Topping Plasterboard
  19. 19. <ul><li>Box sections built with LVL flat sections </li></ul><ul><li>Steel post-tensioning of beams to columns </li></ul><ul><li>Building returns to original shape after earthquake </li></ul>Multistorey - Heavy Sections LVL Box Beam LVL Box Column Post tensioning cable
  20. 20. Multistorey - Heavy Sections University of Canterbury STIC Project www.stic.co.nz for other information/videos
  21. 21. <ul><li>Timber framed houses have been constructed for more than 100 years in New Zealand </li></ul><ul><li>They have been engineered for 30 years </li></ul><ul><li>They have good earthquake resistance </li></ul><ul><li>Multistorey timber design options are being developed </li></ul>Conclusions
  22. 22. <ul><li>Thank you </li></ul><ul><li>Questions? </li></ul>