Using the principle of "Dofen Akumah" for many walls at once: Succah 4a
The size of the cubit used to measure the length of a "curved wall" which becomes part of the roof: Eruvin 3b
Use of a Tepee or lean-to structure: Succah 7b, 19b
If there is a canopy extended beneath/above the roof: Succah 10a, 10b-11a
Using the "Lavud" principle to bridge small gaps, in mid-roof or at the sides: Succah 18a
Validity of Roofing which extends beyond the walls: Succah 19a-b
Using stolen material: Succah 31a
The Material
The material of the Roof: Rosh HaShanah 13a; Succah 36b-37a
Using material which is able to communicate impurity: Succah 11a, 11b-12a
Using wooden, non-receptive vessels: Succah 12b, 15a
Using a mattress, of varying materials, which was designed for roofing, for reclining, or for neither: Succah 19b-20b
Using a vessel with a receptive area, where the receptive area is made to function while full: Succah 12b
Using worn out vessels: Succah 15b-16a
Bunching and binding items: Succah 13a
Using items which grow in bound bunches: Succah 13a
Defining "Bunching" which would be invalid: Succah 13a-b
Material which didn't originally grow from the ground: Succah 11a
Using congealed wine as the roof material: Succah 12a
Using ropes: Succah 12a-b
Using processed forms of flax: Succah 12b
Using inedible vegetation: Succah 12b
Vegetation which would qualify for Bitter Herbs of Pesach Night are invalid for the roof, and are considered as open air, when wet: Succah 13b
Using something which will become disgusting during the holiday: Succah 12b-13a
Using thorny growths: Succah 13a
Other Details of the Material
If the material is connected to the ground: Succah 9b, 11a
Placing the material atop the Succah while the material is still connected to the ground, and then cutting it [& moving it]: Succah 11a-b
If a Percentage of the material is invalid: Succah 13b
Legal amount of invalid material in mid-roof: Succah 14a, 17a-18a
Mixing invalid materials which are atop the Succah, among the valid materials, to annul their presence: Succah 9b, 11a
How to minimize a gap in the roof: Succah 18a
A roof with many small gaps, none of them large enough to invalidate it alone: Succah 22a
Using boards of [more than] 4 hand-breadths' width: Succah 14a-b, 15a, 37a
If the reeds covering the Succah are all askew, pointing in different directions: Succah 22a
Using sanded boards: Succah 15a
If the roof is made up of multiple staggered layers, so that each layer covers a different part: Succah 22a-b
Using boards when they are on their sides: Succah 14b
Considering a combination of boards and sheets to invalidate the roof, from the edge or in the middle: Succah 14a-b, 17b-18a, 37a
Considering excess roofing, beyond where the 4th wall would be [in a case where there are only 3], to be a valid roof for use: Succah 14b
The space to maintain between poles of various types, to allow their use: Eruvin 15b; Succah 15a-b
Considering invalid roofing to be joined together, if the sections of invalid roofing are equal to, or greater, than the gap separating them [Omeid Merubeh Al haParutz/KiParutz]: Eruvin 15b; Succah 15a-b
Allowing the roof material to be supported by the posts of a bed, or on an item which can receive impurity, within the Succah: Succah 21b