Which factor does NOT contribute to the fire-resistance rating of a wall?

The factor that does not contribute to the fire-resistance rating of a wall is related to the brand of paint applied. Fire-resistance ratings are primarily determined by the inherent properties of the materials used in constructing the wall, including the composition and thermal performance of those materials. Thicker walls and the use of fire stop systems also play crucial roles in preventing the spread of fire, as they are designed to withstand fire exposure for a specified period. While paint can have varying degrees of flammability, the brand of paint typically does not significantly impact the structural integrity or fire-resistance capabilities of the wall itself. This is why it does not factor into the fire-resistance rating the same way that the other elements do.