Conventional Roof Framing
Class Exercise 2 - 180
Residential Studies Certificate IV2182D
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.
Note: Hyspan LVL Strutting Beams to Dining / Lounge & Bedroom 1 as shown
2.7700.470 1.070 0.970 1.190 0.8500.8300.970 1.790 1.930 1.8101.310 0.4700.970 1.190 0.970 3.350
0.100 1.680
0.100
4.580 0.100
0.270 3.300 2.620 0.1001.0000.100 2.540 3.770
0.1000.750
2.110 0.1001.4000.1000.6000.100
4.250 0.250
0.3500.530
0.1201.5502.7700.4703.6100.9501.6901.4301.6900.9502.530 0.950
22.910
2.3300.995
0.270 3.3050.100
2.7300.100
0.5000.100
2.9300.100
3.7700.100
7.660 0.250
1.00021.910
1.900
0.100
1.690
0.100
0.250
2.450
0.990
4.11
00.2
50
1.800
3.440
0.250
3.940
4.21
0
0.600
0.250
2.450
0.1000.9
00 0.100
2.000
0.100
2.000
0.250
1.800
1.650
4.10
0
0.270
0.270
7.61
08.1
50
.600
Direction of Ceiling Joists
Workshop
Bed3 Bed 2Family
DiningLounge
Bed 1
Entry
KitchenE.S.BathW.C.L'dry
Garage Hall
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11D12D13
D14
D15
W1 W2 W3 W4 W6 W7
W8
W9W10W11W12W13W14
Floor Plan John Bridges
August 2004Floor Plan Class Exercise 2
Preliminary CalculationsCommon Rafter
True Length of Common Rafter Pitch 180
180
Half Span 3.925
Rise 1.275
Half Span = 8.150 – 0.300 2= 3.925m
Rise = Tan 180 x 3.925 = 1.275m
TLCR = 4.127
TLCR = 3.925 Cos 180
= 4.127m
Calculate Common Rafter Span & RLW of Underpurlin
4.127
RLW = 4.127 2
= 2.064m
2.064
2.064
RLW of Underpurlin = 2.064m Say 2.100m
Span of Rafter = 2.064m Say 2.100m
Calculate Eaves Overhang – Eaves RLW
0.150 0.600
TL O/Hang = 0.600 + 0.150 COS 180
= 0.788m
0.788m
RLW Eaves = 0.788m
Calculate Fan Strut Lengths & Distance X.
2.064
2.064
0.788
Strut = ?
2.064
Strut = Tan180 x 2.064 = 0.671
0.671
run of rafter = 3.925
Strut
Dist. X = 1.862
Distance X = Run of rafter divided by 2 less 100mm plate width: 3.925/2 = 1.962 – 100 = 1862
100mm
width
Calculate Fan Strut Length
0.671
0.671 0.671
Fan Strut = 0.6712 + 0.6712
= 0.949m
or
= 0.671 cos 450
= 0.949m
0.949 0.949
Half Spread Fan Strut = 0.671m
Fan Strut Length = 0.949m
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
Using the information from the Preliminary Calculations&
The Job Specification
Fill in the Project job sheets to arrive at final design requirements.
Member Rule/Table Size CommentsTimber Species
Timber Grade
Supp. No.
Roof Mass
Type/Construct.
Floor to Ceiling height
Eaves Width
Seasoned S/Wood
Fill in comments column with information from project specification
MGP 15
6 – N3
60Kg/m2
Conventional
2.700
0.600
General Information from Project Details
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@
600mmc/c
Single Span
Continuous Span (over more than 1 span)
1. Page 81 – rule 7.2.4 ceiling joists (building practice)
7.2.4
2. Page 98 – rule 7.3.6 ceiling joists (member sizes)
7.3.6
3. Determine Span Table of supplements (supp. 6, N3, s/softwood, MGP 15)
21
4. Find allowable spans for 90 x 35 MGP15 ceiling joists from table 21 supp. 6
2.400
2.800
2. Obtain information for Hanging Beams
Member Rule/Table Size CommentsRoom Span CLW
Hanging Beams R
T
R
Bedroom 1Bedroom 2Bedroom 3Bath / WCLaundryKitchenFamilyDiningLoungeGarageW/shop
1. Page 82 – rule 7.2.5 Hanging Beams (building practice)
7.2.5
2. Page 99 – rule 7.3.7 Hanging Beams (member sizes)
7.3.7
3. Determine Span Table of supplements (supp. 6, N3, s/softwood, MGP 15)
23
4. Determine Hanging Beams to rooms from table 23 supp. 6, MGP15
2.475 1.7202.930 2.0502.730 2.0502.540 1.225 1.680 1.725
3.770 1.7203.770 2.0553.830 2.0553.830 2.0553.300 2.775
2 / 90 x 45120 x 45120 x 35
140 x 452 / 170 x 35
170 x 35170 x 35
N / A
90 x 35
140 x 45
90 x 45
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
Fill in comments column with information from project specification & Prelim. Calcs.
0.600
2.100
0.788
1. Page 86 – rule 7.2.11 Rafters(building practice)
7.2.11
2. Page 105 – rule 7.3.13 Rafters (member sizes)
7.3.13
3. Determine Span Table of supplements (supp. 6, N3, s/softwood, MGP 15)
29
4. Determine Rafter Size from table 29 supp. 6, MGP15, N3(Check - single or continuous span - roof mass – span – O/hang)
120 x 35
4. Obtain information for Collar Ties
Member Rule/Table Size Comments
Collar Ties R
Tor
Length
Check section 7 (Roof Framing) for information – rules & tables for Collar TiesNote: 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.
7.2.16 &7.3.17
Page 110, Table 7.6 – Collar Ties gives required Information
7.6 (page 110)
Refer to floor plan to calculate length of collar tie: 7.610 / 2 = 3.805
3.805
From Table 7.6 – Ties to 4200mm long for F8/MGP12 or higher stress grade – 70 x 35
70 x 35
5. Obtain information for Ridge board
Member Rule/Table Size Comments
Ridge R
T
Not Strutted
Check section 7 (Roof Framing) for information – rules & tables for Ridge boardsNote: Find rules relating to Ridge boards
Page 86, Rule 7.2.12 – The size of Ridge boards shall be determined from Table 7.6
7.2.12
7.6 (page 110)
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
Rafter 120 x 35 MGP 15 Seasoned Softwood
Ridge
0.120
Length of Plumb Cut
Length of Plumb cut = Rafter Depth Cos. Roof Pitch
= 0.120 Cos. 180
= 0.126
0.12
6
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.
5. Obtain information for Ridge board
Member Rule/Table Size Comments
Ridge R
T
Not Strutted
Check section 7 (Roof Framing) for information – rules & tables for Ridge boardsNote: Find rules relating to Ridge boards
Page 86, Rule 7.2.12 – The size of Ridge boards shall be determined from Table 7.6
7.2.12
7.6 (page 110)
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
140 x 19
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
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 =
Check section 7 (Roof Framing) for information – rules & tables for UnderpurlinsNote: Find rules relating to Underpurlins
Page 84, Rule 7.2.10 – UnderpurlinsPage 104, Rule 7.3.12 - Size of Underpurlins Span Table 28 of Supplements
7.2.10
7.3.12
28
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
3.633m
8. Obtain information for Struts (Roof Strutting)
Member Rule/Table Size Comments
Struts R
R
T
or
Straight Strut Length =
Fan Strut Length =
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
7.2.15
7.2.15.3
7.6
From Prelim. Calcs. Fill in lengths for straight & fan struts.
0.671m
0.949m
Using Table 7.6 Determine section size of Struts – (Tile Roof)
90 x 45
70 x 70
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
2.7700.470 1.070 0.970 1.190 0.8500.8300.970 1.790 1.930 1.8101.310 0.4700.970 1.190 0.970 3.350
0.100 1.680
0.100
4.580 0.100
0.270 3.300 2.620 0.1001.0000.100 2.540 3.770
0.1000.750
2.110 0.1001.4000.1000.6000.100
4.250 0.250
0.3500.530
0.1201.5502.7700.4703.6100.9501.6901.4301.6900.9502.530 0.950
22.910
2.3300.995
0.270 3.3050.100
2.7300.100
0.5000.100
2.9300.100
3.7700.100
7.660 0.250
1.00021.910
1.900
0.100
1.690
0.100
0.250
2.450
0.990
4.11
00.2
50
1.800
3.440
0.250
3.940
4.21
0
0.600
0.250
2.450
0.1000.9
00 0.100
2.000
0.100
2.000
0.250
1.800
1.650
4.10
0
0.270
0.270
7.61
08.1
50
.600
Direction of Ceiling Joists
Workshop
Bed3 Bed 2Family
DiningLounge
Bed 1
Entry
KitchenE.S.BathW.C.L'dry
Garage Hall
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11D12D13
D14
D15
W1 W2 W3 W4 W6 W7
W8
W9W10W11W12W13W14
Floor Plan John Bridges
August 2004Beam to Lounge / Dining, Span = 4.110 Beam to Bedroom 1, Span = 3.440
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
• Use Hyspan LVL Span Tables for Residential Building
• Calculate spans for strutting beams from floor plan
• Fill in span information
4.110
3.440
• Spacing is centre of rooms
Centre
Centre
• Determine table number from Hyspan LVL tables to select beam section sizes
Use table 18 for BeamTo Lounge/Dining -Span = 4.110
&Beam to Bedroom 1 -Span = 3.440
Supporting Underpurlins& Hanging Beams
Go to Table 18for member size
RLW = 2.475 B1 = 3.830 L/D
Lounge/ Dining Beam Span = 4.110
Bedroom 1 Beam Span = 3.440
TILE ROOF AND CEILINGMaximum Span (M)
Lounge/ Dining Beam = 300x75
Bedroom 1 Beam = 2/200 x 45
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
• Use Hyspan LVL Span Tables for Residential Building
• Calculate spans for strutting beams from floor plan
• Fill in span information
4.110
3.440
• Spacing is centre of rooms
Centre
Centre
• Determine table numbers from Hyspan LVL tables to select beam section sizes
• Fill in Data for Lounge/Dining Beam
300 x 75
• Fill in Data for Bedroom 1 Beam
T 182/ 200 x 45
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.
2.7700.470 1.070 0.970 1.190 0.8500.8300.970 1.790 1.930 1.8101.310 0.4700.970 1.190 0.970 3.350
0.100 1.680
0.100
4.580 0.100
0.270 3.300 2.620 0.1001.0000.100 2.540 3.770
0.1000.750
2.110 0.1001.4000.1000.6000.100
4.250 0.250
0.3500.530
0.1201.5502.7700.4703.6100.9501.6901.4301.6900.9502.530 0.950
22.910
2.3300.995
0.270 3.3050.100
2.7300.100
0.5000.100
2.9300.100
3.7700.100
7.660 0.250
1.00021.910
1.900
0.100
1.690
0.100
0.250
2.450
0.990
4.11
00.2
50
1.800
3.440
0.250
3.940
4.21
0
0.600
0.250
2.450
0.1000.9
00 0.100
2.000
0.100
2.000
0.250
1.800
1.650
4.10
0
0.270
0.270
7.61
08.1
50
.600
Direction of Ceiling Joists
Workshop
Bed3 Bed 2Family
DiningLounge
Bed 1
Entry
KitchenE.S.BathW.C.L'dry
Garage Hall
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11D12D13
D14
D15
W1 W2 W3 W4 W6 W7
W8
W9W10W11W12W13W14
Floor Plan John Bridges
August 2004Strutting BeamsHanging Beams
Under PurlinsSingle strutsFan struts
Class Exercise 2 – Now Complete