Is a Tallit valid if a woman or child affixed the Sisit strings to the garment, or does Halacha require that specifically an adult male affix the strings for the Tallit to be valid for use?
The Ben Ish Hai (Rabbi Yosef Haim of Baghdad, 1833-1909) addresses this question in Parashat Lech Lecha, and rules that it is preferable for an adult male to affix the Sisit strings to a Tallit. He writes that although a Tallit whose strings were affixed by a woman or child is valid according to the strict Halacha, one should be stringent in this regard in deference to the view of Rabbenu Tam (France, 1100-1171), who disqualified such a Tallit. The Ben Ish Hai adds that a boy who has reached the age of thirteen years and one day may be allowed to affix Sisit, and does not have to be inspected for signs of physical maturity. Whereas in some other areas of Halacha we do not consider a thirteen-year-old an adult until physical maturity has been confirmed, with respect to Sisit we consider a boy an adult from the age of Bar Misva even without verifying his stage of physical development.
Hacham Ovadia Yosef, in his Halichot Olam (vol. 1, p. 8), concurs with the Ben Ish Hai's ruling, and emphasizes that if a woman or young child did, in fact, affix Sisit to a Tallit, the Tallit is nevertheless valid, even though this should preferably be done by an adult male.
Summary: Although it is preferable for an adult male to affix the Sisit strings to the Tallit, if the strings were affixed by a woman or child the Tallit is nevertheless valid for use. A boy may be allowed to affix the Sisit strings immediately upon reaching the age of thirteen years and one day.
