Troxler ICO 4740, Manual Of Operation And Instruction, Page: 43 / 171

ICO 3-9
Figure 6: Roof Penetration
NOTES:
1. Galvanized metal thimble must extend at least 23 cm (9
in.) above and below roof.
2. Galvanized metal thimble must provide at least 15 cm (6
in.) of clearance between the duct and the nearest
combustible material.
3. The point where exhaust exits the cap must be at least
91 cm (36 in.) above the roof.
4. The minimum thickness of all galvanized metal parts is
28 gauge, or that which is called for in local building
codes, whichever is thicker.
5. Seal all joints between thimble and roof and between
thimble and duct with a high-temperature caulk.
6. The overall diameter of all ducts should be 4 inches or
greater and the length should not exceed 4.6 m (15 ft)
from the top of the oven to the point of exhaust.