What is the weight required to apply Coal Tar Pitch (CTP) at about 1/8" thick?

To determine the appropriate weight required to apply Coal Tar Pitch (CTP) at approximately 1/8" thick, it is important to consider the density and application rate of the material. Coal Tar Pitch is typically heavy because of its composition, and it must be applied in sufficient quantity to achieve the desired thickness and performance characteristics of the roof.

The correct answer of 75 lbs/sq relates to the general standard in roofing applications for CTP. When applying it at the specified thickness, this weight ensures adequate coverage and adhesion while also accounting for the properties of the material in relation to the roof's underlying layers. This amount allows the CTP to properly bond to the surface and provides long-lasting protection against the elements.

In comparison, the other options would not provide the necessary coverage or thickness. Weighing less than 75 lbs/sq would result in insufficient material application, potentially leading to inadequate waterproofing and premature wear of the roofing system. Thus, the specified weight ensures the effectiveness and durability that is needed in built-up roofing systems utilizing Coal Tar Pitch.