Roof Flashing Requirements

The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.

Roof flashing requirements.

Manufacturers requirements can vary anywhere from 2 inches to 10 inches and you probably won t be able to see the sidewall flashing completely anyway. The recommended width of step flashings will vary depending on the agency entity being referenced. If metal the flashing should be made of galvanized steel at least 0 019 inches thick irc 2015. The recommended length of step flashing is typically a minimum of 2 inches longer than the exposure of the roofing material.

Both codes also contain requirements for roof decks underlayment flashing structural performance and materials and testing criteria. Flashing shall start at the lower portion of roof to ensure water shedding capabilities of all metal laps. Flashing against a vertical sidewall shall be by the step flashing method. Install shingles over the portion of step flashing on the roof.

The sketch above illustrates the end profile of roof drip edge flashing and shows its placement on the roof. The vertical side will be hidden behind the exterior wall covering material. Check the roof measurements projections flashings slope vents etc check the attic sheathing ventilation insulation. Typically 10 by 8 inch 253 mm x 203 mm flashing is chosen.

All laps shall be a minimum of 4 inches 102 mm fully sealed in approved flashing cement. Step flashing size requirements vary according to manufacturer. Usually you won t see much of drip edge as it s under the roof shingles under the underlayment and behind the roof gutter. Install roof felt prior to installing the step and kick out flashing.

For example 3 tab shingles usually have a 5 5 8 inch 143 mm exposure. The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures. Further your step flashing pieces need to be 10 inches 254 mm long and at least 2 inches 50 mm wider than the exposure of the shingle you re using. Some building codes have specific requirements for underlayment and ice dam protection.

Lengths of drip vary but typically it s sold in ten foot lengths 120. The requirements of these codes must be followed. Install house siding over the step flashing ending at least one inch above the roof surface. Shall be sheet metal or of the same material as the roof covering.

This results in a 2 inch minimum head lap.