A hovering within a Sukkah:
A hovering which is a flat handbreadth wide [8 cm.] or contains one Tefach of width within three Tefach of height [see explanation] and has a height of 10 handbreadths [80 cm.] from the ground, then it has the legal status of a tent and is thus forbidden for one to eat or sleep under them.
The reason for this is because by doing so it is considered that one is eating under the shade of a tent and not under the shade of a Sukkah.
The top of the tent is considered to have the Halachic status of one Tefach wide if it slants in a way that within three Tefach of distance from its top down there is a width of one Tefach. Thus in Exhibit A the tent is considered to have one Tefach wide. However in Exhibit B it is not considered to have a one Tefach top.
A hovering over one’s bed:
Flat: If a hovering is placed over ones bed in the Sukkah, then if it is flat, such as a bunk bed, then one may not sleep under it even if it is less than 10 Tefach from the ground.
The reason: This is due to a Rabbinical decree being that the hovering contains a handbreadth width.
Slanted: However if the hovering is slanted, such as a tent, then if it does not reach 10 Tefach above the bed, then it is permitted to sleep under it.
May one eat or sleep under the table or chair in the Sukkah?
So long as the table or chair does not reach a height of ten Tefach [80 cm.] then it is permitted to even initially sleep or eat under it. [Nevertheless it is best to sleep and eat directly under the Sechach then under a hovering, even if less than 10 Tefach high.]
May one sleep on a bunk bed?
The top bed is within 10 Tefach [80 cm.] from the ground: Then it is disputed amongst Poskim whether one may sleep on the lower bed which is hovered over by the upper bed. Some Poskim rule that it is forbidden, similar to the ruling brought above regarding a bed canopy in which it was ruled that it is forbidden to sleep on such a bed even if the canopy does not reach 10 tefach from above the ground. Other Poskim however permit sleeping on the lower bed based on a differentiation between this case, in which the upper bed is only placed there due to lack of space, and the case of the canopy, in which the canopy is purposely placed to hover the bed as part of the beds furniture, and thus in the former case no decree of the Sages were made.
The bed is higher than 10 Tefach from the ground: It is forbidden to sleep on the lower bed.
Having a decorative sheet under one’s Sechach:
If a decorative sheet is spread under one’s Sechach for purposes of beautification of the Sukkah then it is nullified to the Sukkah and one may eat under it if it is within 4 Tefach [32 cm.] from the Sechach. This applies even if the sheet is 4 Tefach wide [32 cm.] and is a height of 10 Tefach from above ground.
The reason for this is because: The sheet is nullified to the Sechach since it was placed for the need of the Sechach in order to beautify it. As well it is valid being that it does not become defined as invalid Sechach being that it was not placed there to give shade, and only when a hovering is placed for shade can it be defined as invalid Sechach. However if the sheet reaches below 4 Tefach [32 cm.] from the Sechach then it is defined as invalid Sechach.
A sheet less than 4 Tefach wide: Even if the sheet is less than 4 Tefach wide, it may not be placed below 4 Tefach from the Sechach due to a decree that one may come to do so also with a sheet that contains 4 Tefach.
May one eat under a protruding decoration which was placed on ones wall?
If the decoration is within 4 Tefach from the Sechach then it is nullified to the Sechach and one may thus eat under it. If however it is below 4 Tefach from the Sechach then it is forbidden to eat under it.
If the decoration is within 4 Tefach from the Sechach but rolls down past the 4 Tefach then it is questionable whether it is considered an interval or not, and practically it should be avoided.
May one place decorations within four Tefach from the Sechach if they reach below 4 Tefach from ones Sechach?
This is to be avoided due to it being questionable whether or not this decoration is nullified to the Sechach and hence perhaps it is an interval between the person and the Sechach. However there are Poskim which are lenient in this matter so long as the top of the decoration is within four Tefach from the Sechach.
Having a sheet placed in order to catch leaves, bugs or rain:
In time of rain what is better; to eat inside or to cover the Sechach and eat in the Sukkah?
At times of rain it is better to place a sheet over or under the Sechach and prevent rain then go inside.
In times of rain is it proper to eat under an open rain umbrella in his Sukkah?
During Chol Hamoed which is not Shabbos it is preferable to eat under a rain umbrella then to eat outside of the Sukkah, as it is not clear that the umbrella is considered a legal tent which intervenes between the person and the Sechach. Nevertheless due to the doubt no blessing is to be said when eating under the umbrella.
 As opposed to slanted such as a tent.
 Piskeiy Teshuvos 627/1
 So is implied from 627/1 which states: “One who sleeps under a bed which is 10 Tefach high has not fulfilled his obligation”. Now although in 627/4 it is ruled regarding a bed canopy that even if it is less than 10 Tefach high it is Rabbinically forbidden to sleep under it. Nevertheless the difference is that a bed is meant to be slept in top of and not under and thus the Sages made no decree when one sleeps under a bed less than 10 Tefach high. However a bed canopy is meant that one sleep under it and thus the Sages decreed against doing so even if it is less than 10 Tefach from the ground. [M”B 627/8]
 Piskeiy Teshuvos ibid
 Piskeiy Teshuvos 627/3
 Kinyan Torah 5/1
 Sheivet Haleivi 7/36
 Piskeiy Teshuvos 627/4; Sheivet Hakehasiy 3/197
 Piskeiy Teshuvos 627/4
 Sefer Sukkah Hashaleim Miluim 14/3
 Koveitz Mibeis Levi 2 p. 24
 Michaber 629/19
 Magen Avraham ibid; Admur 640/6
 Magen Avraham ibid; Admur 640/6
 Piskeiy Teshuvos 627/2
 As it is not set within the ground and is rather held in one’s hand.