The most important part of the sukkah is the roof, but let’s talk about the walls first. The walls may be made of anything at all, as long as they won’t fall down when the slightest wind blows. Aside from being unacceptable according to Halachah, you also want it to be safe!
Here is a cutaway picture of a sukkah. Perhaps it gives you an idea of how a sukkah should look. Of course, a sukkah usually has four walls, or three walls built against the wall of a house.
A sukkah, to be valid according to Jewish Law, must have a minimum of two long walls and one short wall, and a doorway (either with or without an actual door) in that short wall. However, I have never seen a sukkah built that way. As I said above, every sukkah I have ever seen has always had four walls, and sometimes the fourth wall is the wall of a house. (A sukkah can also be built between two houses, where two of the sukkah walls are the walls of the houses. However, you have to be careful that there are no eaves hanging over the sukkah from the tops of the walls, or the sukkah could become invalid. See below.)
The «roofing» (called s’chach in Hebrew — one of the more difficult words to pronounce in the Hebrew language, to be sure) of the sukkah has some very strict rules. It must be made of pieces of vegetation. Any kind of vegetation is permissible. Bamboo used to be very popular, so were bulrushes. Leaves of any tree are acceptable, as long as they have been completely severed from the ground before they are placed on top of your sukkah. I have seen some people use loose slats of wood.
Each piece of vegetation for the s’chach must not be too wide. An inch or two is fine. Some light must also be able to enter between each piece. The length of the s’chach does not matter.
The s’chach must cast more shade than sun into the sukkah, yet still leave it possible to see some sky between the pieces. In this way, we rely on Hashem, not on a roof.
These days, someone has invented a special type of mat that may be used as s’chach. Please keep in mind that not every mat is permitted. It has to be constructed according to very specific Jewish Laws. If you can get hold of those mats made properly, or if you know how to make them yourself, according to Jewish Law, I can personally testify that they are usually much easier to use.
The s’chach may not lay directly on top of metal, or on top of any wood that has been shaped into a vessel that can hold water. In other words the beams that support the s’chach, or the top of your walls that support the s’chach, may not be made of metal. The walls may be made of metal, and then covered with flat pieces of wood or with canvas or another firm material, and the pieces of s’chach may be laid on top of that. The s’chach may not touch the metal beneath it.
The s’chach may not lay directly on top of wood that has been carved into a concave shape. It may be only flat pieces of wood (or material may cover it).
The s’chach may not be tightly secured. This means that the s’chach may not be nailed down, nor tied down too tightly (and not every type of string may be used). You may pile pieces of wood that are also valid as s’chach over the s’chach to weigh it down and keep it in place. You may bang a nail at each side of the s’chach, not to support the s’chach, but to prevent the pieces of s’chach from rolling off. You may build the walls higher than the s’chach. But you may not nail the s’chach down in any way.
If you do wish to tie down the s’chach, you may use only a simple string that is not constructed of twisted strings, and you must tie it loosely. I am told that butcher’s string qualifies (but I haven’t checked it myself).
If you keep your sukkah intact all year-round, you must remove and replace the s’chach within thirty days before the Sukkos Holiday begins, so that the sukkah is not a permanent fixture. The sukkah must be a temporary dwelling, in which we live for the Holiday. We give up our permanent dwelling for a temporary one, to fulfill the will of Hashem. It is not necessary to comepletely remove the s’chach. It is sufficient to lift each piece up a foot or more into the air, and then put it back down. You can do this with many pieces at a time, as long as they are all replaced by hand, with the intention to fulfill the Mitzvah of Sukkah. Just before you do this, you should say, «L’shaim Mitzvas Sukkah — For the purpose of the Commandment of Sukkah.»
Some construction advice for building larger sukkos: You want the s’chach to be held up without fear of them caving in. You might lay a few two-by-fours across the width of the sukkah. Nail those two-by-fours to the walls of the sukkah, or to posts attached to the walls. (Nailing down the beams is permitted because they will not be used as the s’chach.) You would then lay the s’chach over those two-by-fours. If necessary, lay some two-by-fours across the boards, and then place the pieces of s’chach over the upper ones.
A Sukkah must be outdoors, under the sky. There can be no tree or part of a tree above the Sukkah. Any part of a Sukkah that is beneath anything else is invalid. If there is anything above the sukkah, every part underneath is not sukkah. A very common example is a tree that has branches and leaves leaning over part of a sukkah. The part underneath the leaves and branches is invalid. To eat inside the sukkah that is partly underneath a tree, you must sit in a part of the sukkah that is not underneath anything else.
It is permitted to build a sukkah under a retractable roof. Lots of people have a roof on tracks, and they just roll the roof away, which leaves the sukkah below (with its s’chach on, of course) open to the sky. Whenever it rains, they simply move the roof back over the sukkah.
Many sukkos are built against the wall of a house. But often there is an eave, or a gutter, that leans over the edge of the roof, and thus is over that side of the house. Underneath that eave or gutter the sukkoh is not kosher. This means that the sukkah actually starts a foot or two away from the wall. In that situation, the other three walls are absolutely necessary.
And if you want to build your sukkah on a balcony or porch, and there is another balcony or porch directly above yours, you cannot build a sukkah beneath that balcony, or underneath anything else.
Jewish women are not commanded to eat in a sukkah, because it is a time-bound Mitzvah. In general, with some exceptions, women are not obligated to perform most time-bound Mitzvos. (Their primary focus is on the cycles of their own personal self and how their responsibilities radiate outward, while men’s focus is on factors that control them from outside themselves and attempt to make those responsibilities penetrate inwards. Of course, there is a great deal of overlap between the two necessary approaches. At any rate, this my explanation of the concept. It may be completely wrong.) A woman is therefore not obligated to eat in a sukkah. Before you email me about this, please read «On Equality,» by my wife, Kressel Housman, in which she discusses women’s role in the Torah’s Commandments.
A woman may, if she so chooses, eat in the house during the entire Holiday of Sukkos, if she wishes. Unlike a man, she suffers no loss of personal holiness by eating outside a sukkah during Sukkos. Of course if she chooses to eat in a sukkah she receives reward in Heaven for doing so, and receives holiness from performing this Mitzvah. And if she eats in a sukkah, the Ashkenazi Custom is that she says the proper Brachah (Blessing).
(Incidentally, while there are important reasons that a woman is not required to do many of the Commandments that a man is required to do, and they would be too complicated to go into here, it can be surmised that a woman does not need to do the Mitzvah of Sukkah because in a sense she herself is a sukkah. In many ways, a woman encompasses the Mitzvos she does. One obvious example is how she encompasses a Jewish child before it is born, and thus instills within it the inherent holiness every Jew has. A man does not have the power either to encompass and protect that way, nor to impart that same level of holiness. This is why the home is the mother’s province, in shoring up and strengthening that which encompasses and protects a person, not just physically from the elements, but also spiritually. Through what the mother does, the child develops the deeper spiritual (and emotional) attachment to Judaism that he will always look back at for the rest of his life. That is the true desire of the Jew to «return to the womb.» As such, the Jewish woman is herself a sort of sukkah, and does not need to fulfill the spiritual aspects of sukkah by sitting in a sukkah.)
Most people have the custom of beautifying the Mitzvah by attaching nice signs to the walls. (This is not necessary, just a way of beautifying the Mitzvah.) The signs must convey the decorum necessary for a sukkah, and should depict some holy aspect of Judaism. Generally, the signs will have words from the Torah about the Holiday, some of the prayers recited in the sukkah, pictures of Rabbis, or pictures of Jewish sites in Israel, or Jewish practices from around the year. These should be treated with respect, and packed away carefully during the rest of the year.
The most widespread practice is to hang decorations on the walls, and many also hang some from the beams supporting the s’chach, or from the s’chach itself. Pre-school and nursery-grade children will usually bring home from their Jewish dayschool or daycare center some decorations they made in school. It will make your child proud and happy if you hang them up in your sukkah. Since one of the Commandments of the Holiday is to rejoice, why not give your children an extra reason to rejoice as well?
Since a Sukkah is a holy place, we must conduct ourselves, while in the Sukkah, with an extra level of holiness and caution. And it should help us consider the value of always conducting ourselves that way. Most importantly, we must bear in mind, as we make the Blessing in the sukkah, and as we eat, that we are thanking Hashem for taking us out of Egypt and miraculously protecting our ancestors in the Sinai Desert.