Table of Contents
Advertisement
LIGHTWEIGHT BLOCK-IN SPECIFICATIONS (Continued)
Factory-Built Chimney (Continued)
Framing for Roof (Continued)
To determine the appropriate size of the roof opening, use the
table below. Notice that the first dimension is the same for
every slope listed on the left. This is because the width will
always be the same no matter what slope the roof has. The
second dimension represents the length along the slanted
roof. It is measured along the slope of the roof. The
illustration to the right demonstrates the framing size for the
second dimension.
Chimney
Rafter Size
S L O P E
Temco
2 by 4
0 / 1 2
16 x 16
1 / 1 2
16 x 16 1/2
2 / 1 2
16 x 17
3 / 1 2
16 x 17 1/2
4 / 1 2
16 x 18 1/4
5 / 1 2
16 x 19
6 / 1 2
16 x 19 7/8
7 / 1 2
16 x 20 3/4
8 / 1 2
16 x 21 3/4
9 / 1 2
16 x 22 3/4
1 0 / 1 2
16 x 23 3/4
1 1 / 1 2
16 x 25
1 2 / 1 2
16 x 26 1/8
The 3-Foot, 2-Foot, 10-Foot Rule
The 3-foot, 2-foot, 10-foot rule applies to the height that the chimney must penetrate above
the roof. It states that the chimney must be:
1. At least 3 feet higher than the highest part of the roof opening through which it passes;
2. And at least 2 feet higher than any part of the roof within 10 feet, measured horizontally.
A chimney must meet requirement #1 and requirement #2. This rule, required by all
building codes, applies to both factory-built and masonry chimneys.
Minimum Chimney Height on a Sloped Roof
Type
Chimney
Rafter Size
Superior, FMI, or Marco
2 by 6
16 x 16
16 1/2 x 16 1/2
16 x 16 5/8
16 1/2 x 17
16 x 17 1/4
16 1/2 x 17 1/2
16 x 18
16 1/2 x 18
16 x 18 7/8
16 1/2 x 18 3/4
16 x 19 1/4
16 1/2 x 19 1/2
16 x 20 7/8
16 1/2 x 20 3/8
16 x 21 1/2
16 1/2 x 21 1/4
16 x 23
16 1/2 x 22 1/4
16 x 24 1/4
16 1/2 x 23 1/4
16 x 25 1/2
16 1/2 x 24 1/4
16 x 26 3/4
16 1/2 x 25 1/2
16 x 28 1/8
16 1/2 x 26 5/8
2' Minimum
10'
Type
2 by 4
2 by 6
16 1/2 x 16 1/2
16 1/2 x 17 1/8
16 1/2 x 17 3/4
16 1/2 x 18 1/2
16 1/2 x 19 3/8
16 1/2 x 19 3/4
16 1/2 x 21 3/8
16 1/2 x 22
16 1/2 x 23 1/2
16 1/2 x 24 3/4
16 1/2 x 26
16 1/2 x 27 1/4
16 1/2 x 28 5/8
Ridge
Page 22
Framing Size
Chimney
Type
Rafter Size
M a j e s t i c
2 by 4
2 by 6
17 1/2 x 17 1/2
17 1/2 x 17 1/2
17 1/2 x 18
17 1/2 x 18 1/8
17 1/2 x 18 1/2
17 1/2 x 18 3/4
17 1/2 x 19
17 1/2 x 19 1/2
17 1/2 x 19 3/4
17 1/2 x 20 3/8
17 1/2 x 20 1/2
17 1/2 x 20 3/4
17 1/2 x 21 3/8
17 1/2 x 21 3/8
17 1/2 x 22 1/4
17 1/2 x 23
17 1/2 x 23 1/4
17 1/2 x 24 1/2
17 1/2 x 24 1/4
17 1/2 x 25 3/4
17 1/2 x 25 1/4
17 1/2 x 27
17 1/2 x 26 1/2
17 1/2 x 28 1/4
17 1/2 x 27 5/8
17 1/2 x 29 5/8
3' Minimum
Advertisement
Table of Contents
