Shingle roofs are beautiful to admire and incredibly hard wearing. They require the same maintenance as slate roofs, so we suggest ensuring they are frequently cleared of moss, leaves and other debris.
Naturally, a shingle roof will take in water and although this design will not leak (forming drips or pools of water in your structure) the water held in them will discolor the shingles. This will dry out with the changes in weather and is part of the natural weathering of cedar. The image at the bottom of this post shows a shingle roof starting to weather down.
Although weathering changes will not compromise the build quality or integrity of the structure some of our customers would prefer not to see the changes to the shingles from the interior and prefer to have it lined with cedar or ply board. It depends on the finish you would like and how natural you would like your structure to remain.
We no longer use lead flashing on our structures as we have found that it oxidises and can stain the wood roof. Instead, we dress the shingles to the finial and finish them, watertight like the images shown.