Yes, a sheet of drywall can catch fire if it is in direct contact with a Class A stove pipe or any other hot surface. Class A stove pipes are designed to be double-walled and insulated to minimize heat transfer to the surrounding materials. However, they can still become very hot during stove operation.
Drywall is a combustible material, and its ignition point is relatively low compared to other building materials. If a Class A stove pipe comes into direct contact with drywall, the heat from the pipe can raise the temperature of the drywall to a point where it can ignite. This situation is a fire hazard and should be avoided.
When installing a wood stove or any other appliance with a Class A stove pipe, it is crucial to follow the manufacturer's installation guidelines and local building codes to ensure proper clearance from combustible materials like drywall. Adequate clearance is necessary to prevent the risk of fire and to ensure the safe operation of the stove.
If you have concerns about the proximity of the stove pipe to the drywall, consult a professional stove installer or a building inspector to assess the setup and make any necessary adjustments to ensure safety.