Conventional Roof Framing

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Conventional Roof Framing   Class Exercise 2 -
180             Residential Studies
Certificate IV 2182D

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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.
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Floor Plan Class Exercise 2
Note Hyspan LVL Strutting Beams to Dining /
Lounge Bedroom 1 as shown
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Preliminary Calculations
Common Rafter
True Length of Common Rafter Pitch 180
Half Span 8.150 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
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Calculate Common Rafter Span RLW of Underpurlin
2.064
4.127
2.064
RLW 4.127 2 2.064m
Span of Rafter 2.064m Say 2.100m
RLW of Underpurlin 2.064m Say 2.100m
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Calculate Eaves Overhang Eaves RLW
0.788m
TL O/Hang 0.600 0.150 COS 180
0.788m
RLW Eaves 0.788m
0.150
0.600
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Calculate Fan Strut Lengths Distance X.
Strut ?
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 3.925/2
1.962 100 1862
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Calculate Fan Strut Length
0.671
0.671
Fan Strut ? 0.6712 0.6712
0.949m or 0.671
cos 450 0.949m
0.671
0.949
0.949
Half Spread Fan Strut 0.671m Fan Strut Length
0.949m
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Summary
Rafter Span 2.064 Say 2.100 RLW Underpurlin
2.064 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
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Using the information from the Preliminary
Calculations The Job Specification Fill in
the Project job sheets to arrive at final design
requirements.
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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
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Using A.S. 1684.2 (2006) Section 7 Roof Framing
1. Obtain information for Ceiling Joists to
complete job sheet.
Member Rule/Table Size Comments
Ceiling Joists R T R 90 x 35 _at_ 600mmc/c Single Span Continuous Span (over more than 1 span)
2.400
7.2.4
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2.800
7.3.6

1. Page 81 rule 7.2.4 ceiling joists (building
   practice)

2. Page 98 rule 7.3.6 ceiling joists (member
sizes)
3. Determine Span Table of supplements (supp.
6, N3, s/softwood, MGP 15)
4. Find allowable spans for 90 x 35 MGP15
ceiling joists from table 21 supp. 6
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2. Obtain information for Hanging Beams
Member Rule/Table Size Comments Room Span CLW
Hanging Beams R T R Bedroom 1 Bedroom 2 Bedroom 3 Bath / WC Laundry Kitchen Family Dining Lounge Garage W/shop
7.2.5
2.475 1.720
2 / 90 x 45
2.930 2.050
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120 x 45
2.730 2.050
120 x 35
2.540 1.225
90 x 45
7.3.7
1.680 1.725
90 x 35
3.770 1.720
140 x 45
3.770 2.055
2 / 170 x 35
3.830 2.055
170 x 35
3.830 2.055
170 x 35
140 x 45
3.300 2.775
N / A

1. Page 82 rule 7.2.5 Hanging Beams (building
   practice)

2. Page 99 rule 7.3.7 Hanging Beams (member
sizes)
3. Determine Span Table of supplements (supp.
6, N3, s/softwood, MGP 15)
4. Determine Hanging Beams to rooms from
table 23 supp. 6, MGP15
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3. Obtain information for Rafters
Member Rule/Table Size Comments
Common Rafter R T R Rafter Spacing Span Eaves O/Hang Underpurlin is mid-span of Rafter
0.600
7.2.11
120 x 35
2.100
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0.788
7.3.13
Fill in comments column with information from
project specification Prelim. Calcs.

1. Page 86 rule 7.2.11 Rafters (building practice)

2. Page 105 rule 7.3.13 Rafters (member sizes)
3. 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)

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4. Obtain information for Collar Ties
Member Rule/Table Size Comments
Collar Ties R T or Length
3.805
7.2.16 7.3.17
70 x 35
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 7.2.16 Page 109, Rule 7.3.17
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 7.610 / 2 3.805
From Table 7.6 Ties to 4200mm long for F8/MGP12
or higher stress grade 70 x 35
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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 7.2.12 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
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Refer Table 7.6 (AS 1684.2) 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 0.126
0.120
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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 7.2.12 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 - 0.120
0.126 (Therefore 140 x 19 Ridge) cos 180
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6. Obtain information for Hip Rafter (Hip)
Member Rule/Table Size Comments
Hip Rafter R R T
Note Plan shows Roof is a Gable Roof Therefore
NO HIPS REQUIRED
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7. Obtain information for Under purlins
Member Rule/Table Size Comments
Underpurlin R R T 140 x 70 Span Direct from Span Tables of Supplements. Max. Span Interpolated
7.2.10
7.3.12
3.633m
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Check section 7 (Roof Framing) for information
rules tables for Underpurlins
Note Find rules relating to Underpurlins
Page 84, Rule 7.2.10 Underpurlins Page 104,
Rule 7.3.12 - 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
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8. Obtain information for Struts (Roof Strutting)
Member Rule/Table Size Comments
Struts R R T or Straight Strut Length Fan Strut Length
0.671m
90 x 45 70 x 70
7.2.15
7.2.15.3
0.949m
7.6
Check section 7 (Roof Framing) for information
rules tables for Struts
Note Find rules relating to Struts
Page 87, Rule 7.2.15 Roof Strutting Page
90, Rule 7.2.15.3 Fan Struts. Page 109, Rule
7.3.17 - 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)
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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

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Beam to Lounge / Dining, Span 4.110
Beam to Bedroom 1, Span 3.440
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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
Centre Centre
4.110
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

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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
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RLW 2.475 B1 3.830 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
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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
Centre Centre
4.110
300 x 75
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

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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.
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Strutting Beams
Under Purlins
Single struts
Fan struts
Hanging Beams
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Class Exercise 2 Now Complete