Final answer:
The correct option for installing 3-tab asphalt shingles on a low pitch of 2/12 is 'c', which involves the use of two layers of roofing felt underneath the shingles. This additional protection helps prevent water infiltration on the low-sloped roof.
Step-by-step explanation:
The question pertains to the installation requirements of 3-tab asphalt shingles in roofing, specifically regarding the minimum slope (pitch) at which these shingles can be correctly installed to ensure proper water runoff and roof protection. While the minimum recommended pitch for standard asphalt shingle installation is usually 4/12, in some cases, shingles can be installed on lower-pitched roofs.
Option 'a', suggesting shingles can never be installed on pitches as low as 2/12, is incorrect. Option 'b', proposing the use of hot tar roof coating, is not the standard technique for installing shingles. Option 'd', suggesting the use of 30-year shingles, is irrelevant to the slope consideration.
The correct option is 'c', which states that a 3-tab asphalt shingle can be installed on pitches as low as 2/12 if there are two layers of roofing felt under the shingles. This approach provides additional protection against water infiltration, which can be a greater risk on roofs with a low pitch. The double layer of roofing felt creates a more substantial barrier to water, compensating for the low slope and ensuring better water-shedding capabilities, which is crucial in preventing roof leaks and extending the life of the roofing system.
It is important to follow the manufacturer's specifications and local building codes when installing low-slope roofing systems.