Non-Kli
You may not use a kli for sukka schach.

A kli is any item created with the intention of being used as a tool or utensil to make an activity easier.

Examples

• Bamboo if it had been used for any other purpose.

• Wooden ladder.

• Walking stick.

Non-Edible
A sukka's covering (schach) must consist of non-edible branches, leaves, or other materials of plant origin such as boards. You may use wooden boards (such as 2” x 4”s) to hold up schach, even though lumber is intended to be used for construction.
Size
Boards or tree trunks—whether used as schach or used to hold up schach--must be not more than 15 inches (38 cm) wide. A board--whether used as schach or used to hold up schach--more than 15 inches wide invalidates the area below it and you would have to sit under kosher schach in order to fulfill the mitzva. In the case of a board more than 15 inches wide: If the sukka has only three walls, the board may invalidate the sukka. Consult a rabbi.
Fresh
You may not use branches whose leaves will dry up in less than 8 days, intending to replace the branches with fresh ones during chol ha'moed; the custom is to use evergreen leaves only if you want to use leaves as schach.
Fasteners
Schach on the sukka must stay by itself without fasteners or connectors, even in a place with normally high wind. Any man-made fasteners--such as plastic, metal, or even hemp cord or rope--will invalidate the schach. If the schach will stay without them, then you may use fasteners or connectors as reinforcements.

Year-Round Structures
You may use a pergola, gazebo, or other type of awning frame or roof structure that exists year-round for a sukka as long as the other conditions (size, slope, materials, timing, etc.) are kosher. You must first remove any permanent roof coverings before putting on the schach.

Note The slope of the sukka roof must be less than 45 degrees from horizontal.