Exercises for timber Framing Design

For our exercises we use 3 timber framed buildings  Plan E,  Plan A  and  Plan C
for each we design the following members
:

  •  All roof framing members
  •  All wall framing members inclusive bracing and
  •  all floor framing members.


    There are two parts for each exercise:
    Part A - design of all coupled roof members
    Part B - coupled roof members overlay

  • Plan E will be use to demonstrate the required procedure to fill in the information in the handouts. In no more than 8 Weeks you should have completed the selection of all members for house Pan E. Students then work themselves through the next plan A and later plan C. The lecturer will answer any student's question regarding the member selection or the appropriate rules of the standard. Students how have completed some rows in the roof frame table can check their figures with the lecturer. If students haven't done any work at all correct figures will not be provided.

    What to do first?


    Look at and familiarise yourself with the floor plan, especially the dimensions. Read carefully the specification. To be able to select a member from the Supplements a number of input figures are required. You find some of them in the species. The following specification are taken from Plan E.

    SPECIFICATION

    Roof Construction: -coupled Roof - Steel roof sheeting 0.50mm think and battens, Roof Pitch 26°
    For coupled & non-coupled roof refer to 2.7.4 Roofs;  the steel roof sheeting is given to find the mass of roof materials refer to Table B1.1 & B1.2

    Wind Classification: N2
    The maximum design gust wind speed is given in Table 1.1. If given in m/s refer to column 2 permissible stress method

    Eaves Width: 400mm
    Usually given as horizontal dimension. Remember the overhang is measured in the roof plane
    (i.e. 400/cos 26°)

    Ceiling Lining: 10mm plasterboard
    According to Table B1.2 - 7.5 kg/mē
    . Note the max ceiling mass is 12 kg/mē.

    Roof Frame Timber Type: seasoned, stress grade F.5
    Use N1/N2 Supplement 1

    Roof Battens Spacing: 900mm maximum
    Use Table 32 of N1/N2 Supplement 1

    Rafters Spacing: 900mm maximum
    Needed as input in Table 29 of N1/N2 Supplement 1

    Ceiling Frame timber Seasoned, stress grade F.5
    Use N1/N2 Supplement 1

    Ceiling Joist Spacing: 450mm maximum, NO overbattens
    Needed as input in Table 21 or 22 of N1/N2 Supplement 1

    Strutted ridge and underpurlins
    Indicates rafter is supported at 3 points (wall, underpurlin and ridge). That means rafter span is continuous. Place underpurlin always at midspan
    .

    Beams  Combined strutting/hanging) timber type: seasoned, stress grade MGP 12
    Combined counter/strutting)     OR
    Strutting                           )  HYSPAN LVL
    Counter                            )

    Wall Height 2400mm  (Refer also to specification Wall framing)
    Needed as input in Table 7, 8, 11, 12 & 13 of N1/N2 Supplement 1

    The next step is to fill in the required information.
    Below is an example how to do this.


    TIMBER FRAMING DESIGN

     

    PLAN E

     

    TIMBER ROOF FRAMING

     

    CEILING AND ROOF FRAME INFORMATION

    Ceiling Timber Type: _Seasoned____________  Stress Grade: ______F 5 _______

    Roof Timber Type: ___Seasoned_____________  Stress Grade: _______F5________

    Roof Construction Mass Table:   B 1.1_(P_217)__ Roof Construction Mass: 10 g/mē

    Roof Construction Description: Coupled roof  (Steel roof sheeting 0.50mm thick and battens)

    Eaves Width: ____400 mm____   Alternative Timber Dimensions Table No. ____1.3__

     

     

    COUPLE ROOF - ROOF FRAME

     

    Member

    Rule/Table

    Comments

    Size

    Common Rafter

     

     

    S.G. ___F 5___

    R  7.1.2.2 

     

    R  7.2.11

     

    R  7.3.13.2

     

    T __29___

    Rafter spacing : _900 mm_______

     

    Rafter span: ___2078 mm_______

     

    Rafter overhang: ___445 mm____

     

    Length gross: ___4601 mm_____

    Underpurlin is to be mid length of rafter

     

     

    120 x 35

    Collar Ties

     

    S.G. ___F 5__

    R _7.2.16_

     

    R _7.3.17_

     

    T __7.6__

     

     

     

    Length: __3735 mm__________

     

     

    70 x 45

    or

     90 x 35

    Ridgeboard

     

    S.G. ___F 5__

    R 7.2.12.1

     

    R _7.3.17_

     

    T __7.6__

    Unstrutted/Strutted

     

    Up to_1800 mm_ centres

     

    Up to_2300 mm_ centres

     

     


    140 x 19

     

    140 x 35

     

    Hip

     

    S.G ___F 5___

    R _7.2.13_

     

    R _7.3.17_

     

    T  __7.6__

     

    If underpurlin does not support the hip rafter use a tie-bolt truss system as alternative support

     


    170 x 35

    Roof Battens

     

    S.G ___F 5___

     

    R _7.2.20_

     

    R _7.3.15_

     

    T  __32___

    Roof Cover Type: Sheet metal___

     

    Batten Span: ____900 mm_____

     

    Batten Spacing: __900 mm_____

     

     

    45 x 90

     

     

      Students need to fill in all blue and red figures to complete the exercise.

    Having completed the roof framing you should continue with the wall framing. Remember Pan E must be finished in Week including all overlays.

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