Conventional Roof Framing
Class Exercise 2 - 180
Residential Studies Certificate IV
2182D
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.
21.910
0.270
2.730
3.305
0.100
1.690
1.430
0.100
0.950
3.610
0.530
0.950
2.330
0.470
2.770
1.5500.1200.350
1.800
W13
D15
W12
D6
W11
W10
0.470
0.100
0.270
3.300
Bath
W1
W2
W3
1.190 0.8500.830 0.970
0.100
1.070 0.970
4.580
0.100 0.100
1.000
Kitchen
1.930
0.100 0.750
2.540
W6
W4
1.790
3.770
D3
Bed 1
E.S.
1.310
W7
0.970 1.190 0.970
1.810 0.470
0.100
2.110
0.100
0.100
0.100
1.400 0.600
3.350
4.250
0.250
22.910
Floor Plan Class Exercise 2
Floor Plan
John Bridges
August 2004
Note: Hyspan LVL Strutting Beams to Dining / Lounge & Bedroom 1 as shown
4.210
0.250
3.940
D1
W.C.
2.620
D2
Entry
D7
L'dry
1.680
D5
3.440
D9
4.110
W8
Hall
0.250
D12
D11
2.770
D4
D8
0.990
D13
Lounge
2.450
0.100
0.100
0.900
2.000
Dining
D10
Garage
Direction of
Ceiling
Joists
Family
1.900 0.100 1.690 0.100
Bed 2
Bed3
D14
2.450
1.650
1.800
W9
Workshop
0.250
0.600
0.270
1.690
0.250
W14
0.100
4.100
2.000 0.250
0.270
7.610
8.150
0.950
2.530
0.250
7.660
3.770
.600
0.995
2.930
0.500
0.100
0.100
0.100
1.000
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
Rise 1.275
TLCR = 4.127
180
Half Span 3.925
TLCR = 3.925
Cos 180
= 4.127m
Calculate Common Rafter Span & RLW of Underpurlin
RLW = 4.127
2
= 2.064m
Span of Rafter = 2.064m Say 2.100m
RLW of Underpurlin = 2.064m Say 2.100m
Calculate Eaves Overhang – Eaves RLW
TL O/Hang = 0.600 + 0.150
COS 180
= 0.788m
RLW Eaves = 0.788m
0.150
0.600
Calculate Fan Strut Lengths
& Distance X.
Strut = ?
2.064
Strut = Tan180 x 2.064
= 0.671
Strut
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
Calculate Fan Strut Length
0.671
0.671
Fan Strut =  0.6712 + 0.6712
= 0.949m
or
0.671
0.949
= 0.671
cos 450
= 0.949m
Half Spread Fan Strut = 0.671m
Fan Strut Length = 0.949m
0.949
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.
General Information from Project Details
Member
Rule/Table
Size
Comments
Timber Species Seasoned S/Wood
Timber Grade
MGP 15
Supp. No.
6 – N3
Roof Mass
60Kg/m2
Type/Construct. Conventional
Floor to Ceiling height
Eaves Width
2.700
0.600
Fill in comments column with information from project specification
Using A.S. 1684.2 (2006) – Section 7 Roof Framing
1. Obtain information for Ceiling Joists to complete job sheet.
Member
Ceiling Joists
Rule/Table
Size
R
7.2.4
T
21
90 x 35
@
R
7.3.6
600mmc/c
Comments
Single Span
2.400
Continuous Span (over more than 1
span)
2.800
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
2. Obtain information for Hanging Beams
Member
Rule/Table
Size
Room
Hanging Beams
R
Comments
Span
CLW
7.2.5
/ 90 x 45 Bedroom 1
120 x 45 Bedroom 2
120 x 35 Bedroom 3
90 x 45 Bath / WC
90 x 35 Laundry
140 x 45 Kitchen
2 / 170 x 35 Family
170 x 35 Dining
170 x 35 Lounge
140 x 45 Garage
W/shop
2
T
23
R
7.3.7
2.475
2.930
2.730
2.540
1.720
2.050
2.050
1.225
1.680
1.725
3.770
3.770
1.720
2.055
3.830
2.055
3.830
2.055
3.300
2.775
N/A
1.
Page 82 – rule 7.2.5 Hanging Beams
(building practice)
2.
3.
Page 99 – rule 7.3.7 Hanging Beams
Determine Span Table of supplements
(member sizes)
(supp. 6, N3, s/softwood, MGP 15)
4.
Determine Hanging Beams to rooms from table 23 supp. 6, MGP15
3. Obtain information for Rafters
Member
Common Rafter
Rule/Table
R
7.2.11
T
29
R
7.3.13
Size
120 x 35
Comments
Rafter Spacing
0.600
Span
2.100
Eaves O/Hang
0.788
Underpurlin is mid-span of Rafter
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
4.
Determine Rafter Size from table 29 supp. 6, MGP15, N3
(Check - single or continuous span - roof mass – span – O/hang)
(supp. 6, N3, s/softwood, MGP 15)
4. Obtain information for Collar Ties
Member
Collar Ties
Rule/Table
R
7.2.16 &
7.3.17
Size
70 x 35
or
Comments
Length
3.805
T 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
5. Obtain information for Ridge board
Member
Ridge
Rule/Table
R
7.2.12
Size
Comments
Not Strutted
T 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
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
Ridge
Rafter 120 x 35 MGP 15
Seasoned Softwood
Length of Plumb Cut
Length of Plumb cut = Rafter Depth
Cos. Roof Pitch
0.120
= 0.120
Cos. 180
= 0.126
5. Obtain information for Ridge board
Member
Ridge
Rule/Table
R
Size
7.2.12
Comments
Not Strutted
140 x 19
T 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
cos 180
(Therefore 140 x 19 Ridge)
6. Obtain information for Hip Rafter (Hip)
Member
Hip Rafter
Rule/Table
R
R
T
Size
Comments
7. Obtain information for Under purlins
Member
Underpurlin
Rule/Table
R
7.2.10
R
7.3.12
Size
Comments
140 x 70 Span Direct from Span Tables of
Supplements.
Max. Span Interpolated = 3.633m
T
28
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
8. Obtain information for Struts (Roof Strutting)
Member
Struts
Rule/Table
Size
R
7.2.15
90 x 45
R
7.2.15.3
T
7.6
Comments
Straight Strut Length =
0.671m
Fan Strut Length
0.949m
or
=
70 x 70
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)
9. Obtain information for Strutting Beams
Member
Rule/Table
Strutting Beams
•Use: Hyspan LVL
•Supporting roof
&
Ceiling Loads.
Size
Comments
Location
Span
Lounge/Dining
Bedroom 1
• Use Hyspan LVL Span Tables for Residential Building
• Calculate spans for strutting beams from floor plan
Spacing
21.910
0.270
2.730
3.305
0.100
1.690
1.430
0.100
0.950
3.610
0.530
0.950
2.330
0.470
2.770
1.5500.1200.350
1.800
W13
D15
W12
D6
W11
W10
0.470
0.100
0.270
3.300
Bath
W1
W2
W3
1.190 0.8500.830 0.970
0.100
1.070 0.970
4.580
0.100 0.100
1.000
Kitchen
1.930
0.100 0.750
2.540
W6
W4
1.790
3.770
D3
Bed 1
E.S.
1.310
W7
0.970 1.190 0.970
1.810 0.470
0.100
2.110
0.100
0.100
0.100
1.400 0.600
3.350
4.250
0.250
22.910
Beam to Lounge / Dining, Span = 4.110
Floor Plan
John Bridges
August 2004
Beam to Bedroom 1, Span = 3.440
4.210
0.250
3.940
D1
W.C.
2.620
D2
Entry
D7
L'dry
1.680
D5
3.440
D9
4.110
W8
Hall
0.250
D12
D11
2.770
D4
D8
0.990
D13
Lounge
2.450
0.100
0.100
0.900
2.000
Dining
D10
Garage
Direction of
Ceiling
Joists
Family
1.900 0.100 1.690 0.100
Bed 2
Bed3
D14
2.450
1.650
1.800
W9
Workshop
0.250
0.600
0.270
1.690
0.250
W14
0.100
4.100
2.000 0.250
0.270
7.610
8.150
0.950
2.530
0.250
7.660
3.770
.600
0.995
2.930
0.500
0.100
0.100
0.100
1.000
8. Obtain information for Strutting Beams
Member
Rule/Table
Strutting Beams
•Use: Hyspan LVL
Size
•Supporting roof
&
Ceiling Loads.
Comments
Location
Span
Spacing
Lounge/Dining
4.110
Centre
Bedroom 1
3.440
Centre
• 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
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
RLW = 2.475 B1
= 3.830 L/D
TILE ROOF AND CEILING
Maximum Span (M)
Lounge/ Dining
Beam Span = 4.110
Lounge/ Dining
Beam = 300x75
Bedroom 1
Beam Span = 3.440
Bedroom 1
Beam = 2/200 x 45
8. Obtain information for Strutting Beams
Member
Rule/Table
Strutting Beams
•Use: Hyspan LVL
•Supporting roof
&
Ceiling Loads.
Size
Comments
Location
Spacing
300 x 75
T 18
Span
4.110
Lounge/Dining
Centre
3.440
Centre
2/ 200 x 45
Bedroom1
• 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
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.
21.910
0.270
2.730
3.305
1.690
0.950
1.690
1.430
0.100
3.610
0.530
0.950
2.330
0.470
2.770
1.5500.1200.350
1.800
W13
D15
W12
D6
W11
W10
0.470
0.100
0.270
3.300
D7
D1
L'dry
W.C.
Bath
W1
W2
W3
2.620
4.580
0.100 0.100
1.000
W6
W4
1.790
1.930
0.100 0.750
2.540
3.770
D3
Bed 1
E.S.
Kitchen
1.190 0.8500.830 0.970
0.100
1.070 0.970
1.680
D2
Entry
1.310
W7
0.970 1.190 0.970
1.810 0.470
0.100
2.110
0.100
0.100
0.100
1.400 0.600
4.210
0.250
3.350
4.250
0.250
22.910
Single struts
Strutting Beams
Fan struts
Hanging Beams
Floor Plan
John
Bridges
Under
Purlins
August 2004
3.940
D5
3.440
D9
4.110
W8
Hall
0.250
D12
D11
2.770
D4
D8
0.990
D13
Lounge
2.450
0.100
0.100
0.900
2.000
Dining
D10
Garage
Direction of
Ceiling
Joists
Family
1.900 0.100 1.690 0.100
Bed 2
Bed3
D14
2.450
1.650
1.800
W9
Workshop
0.250
0.600
0.250
W14
0.100
4.100
2.000 0.250
0.270
7.610
0.270
8.150
0.950
2.530
0.250
7.660
3.770
0.100
.600
0.995
2.930
0.500
0.100
0.100
0.100
1.000
Class Exercise 2 – Now Complete