If the walls of the sukkah are 10 tefachim tall but they do not reach up to the sechach the sukkah is kosher as long as the walls are lined up with the roof or within 3 tefachim based on the principle of gud asik mechitzta.
Sukkah roof rules.
The inside of the sukkah must measure at least seven tefachim long by seven tefachim wide.
The roofing material of a sukkah is called schach which pronounced on second thought let s just call it roofing material anyway the roofing material should consist of vegetation of some sort such as branches leaves stalks or grasses.
It s the roof design that is the most important.
The walls of the sukkah may be made of any material but must be sturdy enough to withstand an ordinary wind code of jewish law orach chayim 630.
According to halakha a sukkah is a structure consisting of a roof made of organic material which has been disconnected from the ground for the purpose of the commandment the s chach.
There are few basic rules.
If it is higher than 20 amot it is invalid.
A sukkah must have a shade roof but you must be able to see the stars through it.
A sukkah must be built anew every year for the purpose of the mitzvah.
But the sukkah rules also suggest that enclosure whether at the wall or roof should never be complete and should be partial to allow entry both physical and visual into the sukkah and out towards the sky.
It is meritorious to start building the sukkah immediately after yom kippur even if it is friday because a chance to perform a precept should not be put off.
This is the smallest area in which a person could reasonably be expected to sit.
As such there are a few technical rules as to the proper roof of a sukkah.
It should be at least three feet tall and be positioned so that all or part of its roof is open to the sky.
A sukkah must have three walls.
Most of these rules specify incompletion and permeability.
One must first erect the walls and only then place the sechach covering.
Even if the sukkah is very long it must still measure at least seven tefachim wide in practice this means that the sukkah should preferably measure 70cm x 70cm.
A basic sukkah plan consists of a roof made of organic material supported by walls made from material of your choice.
There is no maximum width or length but the maximum height is 20 amot.