Hello, everyone and thank you in advance for your help!
I am having trouble understanding what quia means in this sentence which is taken from a postclassical law text:

Secundum legem ex corpore Theodosiani si certum petitur de chirographis quia de quinquennio habetur expositum, ideo hanc legem ex Hermogeniano credidimus adiugendam.

Should I translate quia at the beginning of the sentence?

Because (quia), according to the Theodosian Code, it is established (habetur expositum) a lapse of five years (de quinquennio) if a certain quantity is sued in virtue of a written contract (de chrirographis), for that reason we believed that this law from the Hermogenian Code should be added.

Maybe I am misunterstanding the whole sentence.
Any help would be appreciated!