The blaze began between the second and third races and as the building contained a gas cylinder, the start of the 2.10 was delayed by 15 minutes as the local fire brigade attempted to get matters under control.
Immediately after that contest had been run, however, the police and fire brigade reassessed the situation and after initially suspending racing, then decided the meeting should be abandoned.
The nearby houses were evacuated and a 200m safety cordon thrown down around the garden shed. As areas of the track fell inside the safety zone, racing was called off.
In the earlier action, man of the moment Steven Craine was on the mark for the fifth time in the last three racing days when he booted Regal Heights.
The promising young jockey had landed a treble at Musselburgh on Friday and 24 hours later he partnered Ebony Light to victory in the featured Peter Marsh Chase at Haydock Park.
He was once again seen to good effect on Ginger McCain’s charge in the Kennedy Construction Maiden Hurdle.
Auenmoon settled down in the lead and the 80-1 outsider looked like staying there until he was collared on the run-in by Craine on Regal Heights.
The latter, a 12-1 shot, quickly got the better of the argument to win going away by a length.
Earlier Morgan Be won like a long odds-on shot should when he trotted up in the EBF Poster Plus “National Hunt” Novices’ Hurdle (Qualifier).
Tony Dobbin tracked the leaders on Morgan Be before allowing him to stride on three out and he came home to score eased down by eight lengths from Kempski.
Green Ideal was another to appreciate the heavy going when he ground out victory in the Giles Insurance Conditional Jockeys’ Handicap Chase.
The 13-2 chance took over from the front-running Jolly Boy racing off the home turn and under a strong drive from Tom Dreaper fought off a series of challengers to land the spoils by a length from Fountain Brig.