Evenly space the tubes to receive maximum light. Mark the rafters with tape so that you can use them as references when cutting the middle hole. Measure and mark the decided distance of the center of the tube from a reference wall. Once you have marked the center point of the tube, use a piece of scrap wood to make a compass to mark the hole to be cut out of the ceiling. With a screw in one hole and a pencil in the other, you can mark a perfect circle.
Using a long drill bit, drill a hole in the center of the circle up through the roof above, marking it as well. With a spade bit, make a starter hole. Cut out the ceiling with a jigsaw. Cut the hole adjacent to one of the rafters. You’ll need to anchor the pipe to it later.
Up on the roof, use the nail and the cut out piece of ceiling to cut a perfectly matching hole. Place the flashing under some of the roofing material and then slide the tube into place. Trim the roofing for a tight fit. To hold the tube steady, screw it to the adjacent joist.
Attach the self-adhesive weather stripping to the top of the tube and caulk the flashing to the roof before screwing it down. Add some caulk where the tube and flashing meet and smooth it out with a finger to create a weatherproof seal. Attach the storm collar directly over that area. Tighten it down and add caulk. Attach the dome clamp and the dome to the top of the pipe and tighten it down with a screwdriver.
Back inside, the pipe is finished by attaching foam tape to the outer part of the flange on the diffuser dome. Place the diffuser over the bottom of the tube and screw into place. Attach the plastic screw caps and then the finish ring.