Exercise Template Roof Frame Design

This exercise refers to a timber framed building  Plan E.
Click here to access the calculations for roof members

Design the following members

  •  All roof frame members
  •  All wall frame members inclusive bracing and
  •  all floor frame members.
There are two parts for Roof Framing:

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 a form. Work through all other timber frame members (wall & floor) of Plan E. We can help you to complete the member selection for the rest of house Pan E.

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.


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.







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__









Common Rafter



S.G. ___F 5___



R  7.2.11




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


 90 x 35



S.G. ___F 5__



R _7.3.17_


T __7.6__



Up to_1800 mm_ centres


Up to_2300 mm_ centres



140 x 19


140 x 35




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.

Eaxample Roof Framing completed now continue with the wall & floor framing.

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