1. Conventional Roof Framing Residential Studies Certificate IV
Class Exercise
Residential Studies Certificate IV
2182D

2. Using the Floor Plan & Details provided
complete the Preliminary Calculations
so that the most economical Size, Span and Spacing
Of the Ceiling and Roof members can be achieved.

3. Floor Plan Class Exercise 2
Note: Hyspan LVL Strutting Beams to Dining / Lounge & Bedroom 1 as shown

4. Preliminary Calculations
Common Rafter
True Length of Common Rafter Pitch 180
Half Span = – 0.300 2
= 3.925m
Rise = Tan 180 x 3.925
= 1.275m
TLCR = 4.127
Rise 1.275
TLCR = 3.925
Cos 180
= 4.127m
180
Half Span 3.925

5. Calculate Common Rafter Span & RLW of Underpurlin
2.064
4.127
2.064
RLW = 4.127 2
= m
Span of Rafter = 2.064m Say 2.100m
RLW of Underpurlin = 2.064m Say 2.100m

6. Calculate Eaves Overhang – Eaves RLW
0.788m
TL O/Hang =
COS 180
= m
RLW Eaves = 0.788m
0.150
0.600

7. Calculate Fan Strut Lengths & Distance X.
2.064
2.064
Strut = Tan180 x 2.064
= 0.671
2.064
Strut
0.788
0.671
Dist. X = 1.862
run of rafter = 3.925
100mm
width
Distance X = Run of rafter divided by 2 less 100mm plate width: /2 = – 100 = 1862

8. Calculate Fan Strut Length
0.671
0.671
Fan Strut = 
= m or =
cos 450
0.671
0.949
0.949
Half Spread Fan Strut = 0.671m
Fan Strut Length = 0.949m

9. Summary: Rafter Span = 2.064 Say 2.100
RLW Underpurlin = Say 2.100
Overhang eaves = 0.788
Purlin horizontal Set Out, “Distance X” = 1.862
Half Spread Fan Strut = .671
Full spread Fan Strut = 1.342
Fan Strut Length = 0.949

10. Using the information from the Preliminary Calculations &
The Job Specification
Fill in the Project job sheets to arrive at final design requirements.

11. Member Rule/Table Size Comments
General Information from Project Details
Member
Rule/Table
Size
Comments
Timber Species
Timber Grade
Supp. No.
Roof Mass
Type/Construct.
Floor to Ceiling height
Eaves Width
Seasoned S/Wood
MGP 15
6 – N3
60Kg/m2
Conventional
2.700
0.600
Fill in comments column with information from project specification

12. Member Rule/Table Size Comments 90 x 35 @
Using A.S (2006) – Section 7 Roof Framing
1. Obtain information for Ceiling Joists to complete job sheet.
Member
Rule/Table
Size
Comments
Ceiling Joists R T
90 x 35 @
600mmc/c
Single Span
Continuous Span (over more than 1 span)
7.2.4
2.400 21
2.800
7.3.6
Page 81 – rule ceiling joists (building practice)
2. Page 98 – rule ceiling joists (member sizes)
Determine Span Table of supplements (supp. 6, N3, s/softwood, MGP 15)
Find allowable spans for 90 x 35 MGP15 ceiling joists from table 21 supp. 6

13. Hanging Beams 2. Obtain information for Hanging Beams 7.2.5 23 7.3.7 R
Member
Rule/Table
Size
Comments
Room Span CLW
Hanging Beams R T
Bedroom 1
Bedroom 2
Bedroom 3
Bath / WC
Laundry
Kitchen
Family
Dining
Lounge
Garage
W/shop
7.2.5
2 / 90 x 45 23
120 x 45
120 x 35
7.3.7
90 x 45
90 x 35
140 x 45
2 / 170 x 35
170 x 35
170 x 35
140 x 45
N / A
Page 82 – rule Hanging Beams (building practice)
2. Page 99 – rule Hanging Beams (member sizes)
Determine Span Table of supplements (supp. 6, N3, s/softwood, MGP 15)
Determine Hanging Beams to rooms from table 23 supp. 6, MGP15

14. Member Rule/Table Size Comments
3. Obtain information for Rafters
Member
Rule/Table
Size
Comments
Common Rafter R T
Rafter Spacing
Span
Eaves O/Hang
Underpurlin is mid-span of Rafter
7.2.11
120 x 35
0.600 29
2.100
7.3.13
0.788
Fill in comments column with information from project specification & Prelim. Calcs.
Page 86 – rule Rafters (building practice)
2. Page 105 – rule Rafters (member sizes)
Determine Span Table of supplements (supp. 6, N3, s/softwood, MGP 15)
Determine Rafter Size from table 29 supp. 6, MGP15, N3
(Check - single or continuous span - roof mass – span – O/hang)

15. Member Rule/Table Size Comments
4. Obtain information for Collar Ties
Member
Rule/Table
Size
Comments
Collar Ties R T or
Length
&
7.3.17
70 x 35
3.805
7.6 (page 110)
Check section 7 (Roof Framing) for information – rules & tables for Collar Ties
Note: Find rules relating to Collar Ties.
Page 90 Rule & Page 109, Rule – Other members or Components,
states that Table 7.6 give details for miscellaneous roof
framing members not given in span tables of the supplements.
Page 110, Table 7.6 – Collar Ties gives required Information
Refer to floor plan to calculate length of collar tie: / 2 = 3.805
From Table 7.6 – Ties to 4200mm long for F8/MGP12 or higher stress grade – 70 x 35

16. Member Rule/Table Size Comments
5. Obtain information for Ridge board
Member
Rule/Table
Size
Comments
Ridge R T
Not Strutted
7.2.12
7.6 (page 110)
Check section 7 (Roof Framing) for information – rules & tables for Ridge boards
Note: Find rules relating to Ridge boards
Page 86, Rule – The size of Ridge boards shall be determined from Table 7.6
Table 7.6 Ridge boards – Refers to Unstrutted ridges in coupled roofs has having a depth not less
than length of Rafter Plumb-Cut x 19mm thick

17. Ridge 0.126 Rafter 120 x 35 MGP 15 Seasoned Softwood
Refer Table 7.6 (AS ) page 110,
Ridge depth = rafter plumb cut x 19mm thick.
Therefore use 140 x 19 MGP 15 S/wood.
0.126
Rafter 120 x 35 MGP 15
Seasoned Softwood
Length of Plumb Cut
Length of Plumb cut = Rafter Depth
Cos. Roof Pitch
= 0.120
Cos. 180 =
0.120

18. Member Rule/Table Size Comments
5. Obtain information for Ridge board
Member
Rule/Table
Size
Comments
Ridge R T
Not Strutted
7.2.12
140 x 19
7.6 (page 110)
Check section 7 (Roof Framing) for information – rules & tables for Ridge boards
Note: Find rules relating to Ridge boards
Page 86, Rule – The size of Ridge boards shall be determined from Table 7.6
Table 7.6 Ridge boards – Refers to Unstrutted ridges in coupled roofs has having a depth not less
than length of Rafter Plumb-Cut x 19mm thick
Calculate Rafter Plumb-Cut Length = (Therefore 140 x 19 Ridge)
cos 180

19. Member Rule/Table Size Comments
6. Obtain information for Hip Rafter (Hip)
Member
Rule/Table
Size
Comments
Hip Rafter R T
Note: Plan shows Roof is a Gable Roof – Therefore NO HIPS REQUIRED

20. Member Rule/Table Size Comments
7. Obtain information for Under purlins
Member
Rule/Table
Size
Comments
Underpurlin R T
140 x 70
Span Direct from Span Tables of Supplements.
Max. Span Interpolated =
7.2.10
7.3.12
3.633m 28
Check section 7 (Roof Framing) for information – rules & tables for Underpurlins
Note: Find rules relating to Underpurlins
Page 84, Rule – Underpurlins
Page 104, Rule Size of Underpurlins Span Table 28 of Supplements
Refer Table 28 – Continuous Span - for allowable span to Underpurlin
(Rafter spacing = 0.600, RLW = 2100 & Roof Mass = 60Kg/m2)
Interpolate allowable Max. Span for Underpurlin size 140 x 70 from Table 28

21. Member Rule/Table Size Comments
8. Obtain information for Struts (Roof Strutting)
Member
Rule/Table
Size
Comments
Struts R T or
Straight Strut Length =
Fan Strut Length =
7.2.15
90 x 45
70 x 70
0.671m
0.949m
7.6
Check section 7 (Roof Framing) for information – rules & tables for Struts
Note: Find rules relating to Struts
Page 87, Rule – Roof Strutting & Page 90, Rule Fan Struts.
Page 109, Rule The size of Miscellaneous roof members
shall be determined from Table 7.6
From Prelim. Calcs. Fill in lengths for straight & fan struts.
Using Table 7.6 Determine section size of Struts – (Tile Roof)

22. Member Rule/Table Size Comments
9. Obtain information for Strutting Beams
Member
Rule/Table
Size
Comments
Strutting Beams
Supporting roof
&
Ceiling Loads.
Use: Hyspan LVL
Location Span Spacing
Lounge/Dining
Bedroom 1
Use Hyspan LVL Span Tables for Residential Building
Calculate spans for strutting beams from floor plan

23. Beam to Lounge / Dining, Span = 4.110
Beam to Bedroom 1, Span =

24. Member Rule/Table Size Comments
8. Obtain information for Strutting Beams
Member
Rule/Table
Size
Comments
Strutting Beams
Supporting roof
&
Ceiling Loads.
Use: Hyspan LVL
Location Span Spacing
Lounge/Dining
Bedroom 1
4.110
Centre
3.440
Use Hyspan LVL Span Tables for Residential Building
Calculate spans for strutting beams from floor plan
Fill in span information
Spacing is centre of rooms
Determine table number from Hyspan LVL tables to select beam section sizes

25. Use table 18 for Beam
To Lounge/Dining -
Span = 4.110
&
Beam to Bedroom 1 -
Span = 3.440
Supporting Underpurlins
& Hanging Beams
Go to Table 18
for member size

26. RLW = 2.475 B1 = 3.830 L/D Lounge/ Dining Beam Span = 4.110
TILE ROOF AND CEILING
Maximum Span (M)
RLW = B1
= L/D
Lounge/ Dining
Beam Span = 4.110
Lounge/ Dining
Beam = 300x75
Bedroom 1
Beam Span = 3.440
Bedroom 1
Beam = 2/200 x 45

27. Member Rule/Table Size Comments
8. Obtain information for Strutting Beams
Member
Rule/Table
Size
Comments
Strutting Beams
Supporting roof
&
Ceiling Loads.
Use: Hyspan LVL
Location Span Spacing
Lounge/Dining
Bedroom1
300 x 75
4.110
Centre
T 18
2/ 200 x 45
3.440
Use Hyspan LVL Span Tables for Residential Building
Calculate spans for strutting beams from floor plan
Fill in span information
Spacing is centre of rooms
Determine table numbers from Hyspan LVL tables to select beam section sizes
Fill in Data for Lounge/Dining Beam
Fill in Data for Bedroom 1 Beam

28. Part A can now be completed.
On the plan supplied clearly mark all Hanging Beams, Underpurlins
and any Strutting Beams & / or Special Strutting Beams supporting
Roof and Ceiling loads.

29. Single struts
Strutting Beams
Under Purlins
Fan struts
Hanging Beams

30. Class Exercise 2 – Now Complete