A More Mehudar Mitzvah

Rav Mordechai Finkelman, mashgiach of Yeshivas Ohr Hachaim, received a generous offer from a friend. The friend offered to build Rav Finkelman a sukkah that would be part of his house. For Sukkos, he would simply remove the roof, replace it with schach, and have an almost instant sukkah. Rav Finkelman demurred; he wanted to build the sukkah from scratch every year himself. He said, “I want to schlepp the boards”. Such is Rav Finkelman’s love for mitzvos.
What type of mitzvah is building a sukkah? Is it a mitzvah itself or just a preparatory action to enable one to fulfill the mitzvah of sitting in a sukkah? The Mishna in Shavuos implies it is its own independent mitzvah. The Mishna teaches us that oaths made not to fulfill mitzvos are not valid. For example, if someone swears he will not eat matzah on Pesach night, the oath is invalid. One example cited explicitly in the Mishna is an oath not to build a sukkah. If someone declares he will not build a sukkah, the oath is invalid.