Final answer:
Step flashing consists of small L-shaped metal pieces interwoven with roof shingles during skylight installation to ensure a watertight seal.
Step-by-step explanation:
When installing skylight flashing, the small pieces of L-shaped metal that are interwoven with the roof shingles are known as step flashing. Step flashing is used to ensure a watertight seal around the skylight, as each piece is laid in conjunction with a shingle and then the next higher piece overlaps it to direct water away from the skylight and down the roof.
There are different types of flashings used in roofing for various situations. Counter flashing is used to cover step flashing and can be seen above the roofline, such as against a chimney or wall. Valley flashing is used where two sloping roof sections create a valley. Drip edge flashing is installed at the edges of the roof to help control the flow of water away from the roof. However, for the purpose of integrating with shingles around a skylight, step flashing is the correct choice.