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Common Nails Required for Rafter Ceiling Joist Heel Joint Connections

Civil Engineering Design Knowledge

 

Rafter Slope
Rafter Spacing
Ground Snow Load (psf)
30
50
70
Roof Span (Feet)
12
20
28
36
12
20
28
36
12
20
28
36
Required number of 16d nails per heel joint splices
3:12
12
4
6
8
11
5
8
12
15
6
11
15
20
16
5
8
11
14
6
11
15
30
8
14
20
26
24
7
11
16
21
9
16
23
30
12
21
30
39
4:12
12
3
5
6
8
4
6
9
11
5
8
12
15
16
4
6
8
11
5
8
12
15
6
11
15
20
24
5
9
12
16
7
12
17
22
9
16
23
29
5:12
12
3
4
5
7
3
5
7
9
4
7
9
12
16
3
5
7
9
4
7
9
12
5
9
12
16
24
4
7
10
13
6
10
14
18
7
13
18
23
7:12
12
3
3
4
5
3
4
5
7
3
5
7
9
16
3
4
5
6
3
5
7
9
4
6
9
11
24
3
5
7
9
4
7
10
13
5
9
13
17
9:12
12
3
3
3
4
3
3
4
5
3
4
5
7
16
3
3
4
5
3
4
5
7
3
5
7
9
24
3
4
6
7
3
6
8
10
4
7
10
13
12:12
12
3
3
3
3
3
3
3
4
3
3
4
5
16
3
3
3
4
3
3
4
5
3
4
5
7
24
3
3
4
6
3
4
6
8
3
6
8
10

For SI: 1 inch = 25.4mm, 1 foot = 308.4mm, 1 pound per square foot = 0.0479Pa

  1. 40d box nails can be substituted for 16d common nails
  2. Nailing can be reduced if 25% of nails are clinched
  3. Heel joint connections not required when ridge is supported by load-bearing wall, header or ridge wall
  4. When intermediate support is provided by vertical struts or purlins to load bearing wall, the tabulated heel joint connection requirements shall be reduced proportionally to the reduction in span.
  5. Equivalent nailing patterns are required for ceiling joist to ceiling joist lap splices.
  6. When rafter ties are substituted for ceiling joists, the heel joint connection requirement shall be taken as the tabulated heel joint connection requirement for two-thirds of the actual rafter-slope.
  7. Tabulated heel joint connection requirements assume that ceiling joists or rafter ties are located at the bottom of the attic space. When ceiling joists or rafterties are located higher in the attic, heel joint connection requirements shall be increased by the following factors:
HC/HR
Heel Joint Connection Factor
1/3
1.5
1/4
1.33
1/5
1.25
1/6
1.2
1/10 or less
1.11

Where:
HC = Height of ceiling joits or rafter ties measured vertically above top ot the rafter support walls

HR = Height of roof ridge measured vertically above the top o fthe rafter support walls.

References: International Residential Code

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