For Pompey it was the second time they have failed to overcome ten men this season and are still looking for their first home win.
Aston Villa had a player shown a red card early in their visit to Fratton Park and once again Portsmouth could have no complaints about the outcome.
Butt's dismissal came as he and Portsmouth new signing Dario Silva contested a free-kick about to be taken by Laurent Robert.
Silva appeared to throw out his arm and Butt looked to have retaliated by aiming a kick at the Uruguayan international.
Referee Dermot Gallagher did not see the incident but had his attention drawn by a flag-waving assistant. Silva was shown a yellow card and Butt departed for the dressing room leaving Birmingham to cope with ten men.
Butt's sending-off was the culmination of a hectic first half of two goals and many more incidents.
Damien Johnson cleared from the line a shot by the busy Lomana LuaLua as the prelude to Pompey's goal.
Robert took the corner on the right and as the Birmingham defence stood motionless LuaLua was unmarked when he shot past the unprotected Maik Taylor from ten yards.
But there was no time for Portsmouth celebrations because Birmingham were level in the sixth minute with an equally soft goal.
Jermaine Pennant took a free-kick on the right and Jiri Jarosik was also unattended as he headed in for his second goal since arriving on loan from Chelsea.
Jarosik brought a good save from Jamie Ashdown before being forced from the pitch by injury with three minutes of the first half remaining.
Muzzy Izzet came on as his replacement and made a huge difference in midfield with his non-stop combative performance.
Robert was always a danger with his free-kicks and corners and another of his free-kicks posed problems in the 30th minute, but luckily for Birmingham Matthew Upson was on the line to block the shot.
Then came the dismissal of Butt, changing the complexion of the match and forcing angry manager Steve Bruce to make tactical changes.
Bruce was on the pitch as referee Gallagher blew for half-time to continue his protests and to make it clear what he felt about the petition.
Bruce took off Mikael Forssell at half-time and brought on Jamie Clapham as substitute, pushing left-back Julian Gray into midfield.
Birmingham were much sounder in defence, conceding large chunks of possession to Portsmouth and holding on for the draw.
Even so, Portsmouth had the chances to have won it.
Andy O'Brien headed over in the 51st minute from close range when unmarked at another free-kick by Robert and there were cries for a penalty from the home fans when Silva appeared to be hauled back by his shirt by the desperate Olivier Tebily.
Taylor made a superb save in the 67th minute to keep out a goalbound shot from Gary O'Neil after the England Under-21 International had blasted a shot to the goalkeeper's left.
Taylor went full length to turn the shot away as Birmingham somehow held on.
Taylor made another good save from Silva in the 77th minute and substitute Zvonimir Vukic somehow put a left-foot shot over the bar from ten yards.
There was more drama in injury time when Robert fired in a superb left-foot free-kick from 30 yards which Taylor spilled but O'Neil, following up, could only turn the ball wide.
Salif Diao got through plenty of work for Portsmouth but earned a yellow card for one of many free-kicks he conceded in another competitive display.
Man of the Match: Maik Taylor - A couple of outstanding saves form the Northern Ireland international denied Portsmouth a win as Birmingham held on a man short.