George,
Water will go around the walls unless you bond it - no 2 ways about it. A false wall is fine, just keep in mind that the standpipe is now the *real* overflow and you need to keep sump capacity for that water level.
I try for 4" minimum access in overflows. Just to get my arm in there and being able to maneuver anything requires at least that much IME.
Luis,
IMO just get the heavy damage. Better to err on the side of caution and have too much capability than to not get enough and have to go through it again. It's only $10 difference
HTH,
James
Water will go around the walls unless you bond it - no 2 ways about it. A false wall is fine, just keep in mind that the standpipe is now the *real* overflow and you need to keep sump capacity for that water level.
I try for 4" minimum access in overflows. Just to get my arm in there and being able to maneuver anything requires at least that much IME.
Luis,
IMO just get the heavy damage. Better to err on the side of caution and have too much capability than to not get enough and have to go through it again. It's only $10 difference

HTH,
James