Instructions 1 Clear roof surface of all debris and dirt particles and apply the underlayment. 2 Move on to the eave starter strip and apply. 3 Install gable edge trim, valleys and flashing. The flashing for a metal roof has a return flange. This return flange acts as a channel so that water can run off the roof under the shingles. It is extremely important that the return flange does not get dented, flattened or in any other way damaged. 4 Prepare shingles and hip caps for installation and install them. The bottom shingle needs to be notched for the run off water to flow out. All shingles need to be fastened down with a nail clip on the outside of the return flange. In order to have the water run freely along the shingles you will need to install some shingles into the flashing. You will need to have 1/4-inch gap separating the edge of the shingle and the inside of the flashing. 5 Start to lay out your shingles from the flashing. It is important that you work to the left and stagger your pattern with 1/2, 3/4 and 1/4 shingles. Now mount the ridge caps. 6 Choose whether or not you want siding corners and apply if desired.