If I have a coat that is slit up the side rov of the way up so that it is chayav in tzitzit, if I sew on some buttons (snap? regular?) to keep it closed below rov, is it no longer chayav in tzitzit, or do I need to properly sew it closed? Sources always appreciated.
A case of sewing the corners does not exempt you from tzitzis because we assume 'if he didn't want the corner, he should have cut it and thrown it away'. Rather, he is planning on undoing them at some point and the corners are still considered a significant part of the garment. (SA OC 10:3 and MB)
We see (at least) 2 halachos:
Based on the above, it would seem that snap would not exempt. Sewing would, since there is no logic of 'if he didn't want the corner...' (Also, note the Biur Halacha there who says that you don't apply the above "if he..." if that is the normal manufacturing method.
I think it would still require tzitzit if you snap, button, or tie it.
I was making tzizit with my local-Rabbi, and I decided I wanted to cut the sides of an undershirt and attach tzizit to it, then button the sides together so that my tzizit wouldn't get bunched and out of place. My Rabbi said it would be kosher, but I should make sure the sides are open when I put them on, say the brucha, and then button the sides.
I also remember seeing (I think in the Jewish Encyclopedia) a drawing of a Shepherd's Coat, similar to this, but without the shoulder pieces, which required tzizit, even though it had buttons up the front.