Teamplay mode flags

1      Normal teamplay
2      Half direct team damage
4      No direct team damage
8      Half explosive team damage
16     No explosive team damage
32     Less players help (handicap)
64     Less score help (handicap)
128    Half direct team armor damage
256    No direct team armor damage
512    Half explosive team armor damage
1024   No explosive team armor damage

To disable team damage completely: 4 + 16 + 256 + 1024 = 1300

It is recommended to have team damage disabled on public servers as it will only cause grief with grenades, demoman etc.