The double-points GT World Challenge Europe round will now begin at 4pm local time rather than 3:30pm to enable barrier repairs to be completed.
An extended section of the barrier on the outside of the track on the run from La Source to Eau Rouge was seriously damaged in a three-car accident in which Raul Guzman was injured.
Target Racing driver Guzman was battling with Jonathan Cecetto and Super Trofeo points leader Kevin Gilardoni over sixth place when the accident happened as the cars accelerated through the kink that follows the hairpin.
Cecotto turned sharp left across the track after Guzman squeezed Gilardoni.
Mexican Guzman was diagnosed with a broken lower left leg at the circuit medical centre and has been transferred to hospital in nearby Liege for confirmation as well as a scan on his back.
Gilardoni and Cecotto were uninjured in the accident.
The race was not restarted after the accident, which happened with 15 minutes of the 50-minute race remaining.
Yuki Nemoto was declared the winner, while Guzman, Gilardoni and Cecotto were classified sixth through eighth.
The grid for the 24 Hours will now form up on the top straight in front of the Formula 1 pits, but the start will take place on the straight in front of the old pits between La Source and Eau Rouge.
The double-points Endurance Cup round of the GTWCE at Spa starts at 4:00pm local on Saturday, and you can watch all the action live on Motorsport.tv.