The white cedar single stains described in this thread are mostly applied by dipping the shingles in stain at the factory which provides the best protection. Weatherwash is a brand of interior furniture stain that can be used on exterior wood with a protective coating of Weatherwash's Exterior Water Sealer. That seems like additional expense for less protection.

Your house looks more like red cedar which can be left to age without a stain. White cedar shingles are normally stained at the factory so all sides are protected. What is often used in New England to make white cedar shingles turn a pale gray is Cabot's Bleaching Oil, a mixture of a bleaching chemical and a semi-transparent grey stain. Here is a link that might be useful: Cabot's Bleaching Oil

Thank you, we are pleased with how our home came out. And it is a smaller home. It's fundamentally a 2 bedroom ranch with a finished walk out basement. We did not use insulating panels on the back as we built a green home. The living space in the house is sealed in an envelope of closed cell insulation. We also have 5kw of solar panels on the roof, geothermal heating and cooling, and passive solar design with only a few windows on the north side, many windows on the back, southern side. We have quite a few other green elements, but those are the main ones. This is our retirement home, so we built for low maintenance. All of the trim work is azek. The only wood that will need maintaining on the outside is the beadboard ceiling used in the front entry and the mahogany front door. And we installed a 50 year roof...which keeps shingles out of the landfill longer and it means we won't have to rip off the solar panels and reinstall just to replace the roof.

Cedar shingles in New England do not turn an even gray color from being left untreated in the sun. In New England white cedar shingles are stained to look the color you like or bleaching oil is applied to help them fade to a silver gray color. Red cedar shingles can be stained or left unfinished. When unfinished they discolor unevenly which is generally desired. Shingles that have turned black are not necessarily rotting. Certain parts of the house will naturally become darker from surface fungi. These shingles will probably need to be replaced in 30 or 40 years. If that is an issue you could use a preservative but the shingles tend to look like fake shingles and that is not very popular in New England. Red Cedar shingles in Dedham, MA Untreated red cedar starting to turn dark stained white cedar on the Cape Solid stained shingles Wellesley MA Maine Cabot's Bleaching Oil stain