Cedar Shingle Maintenance

[swloritz]

I have a project where I need to protect existing cedar shingles from UV rays yet allow them to weather dark. I will be doing this to multiple buildings. I will also be replacing some roofs with new ones and would like to protect them from UV rays also. I do need to allow the shingles to weather dark. Does anyone have any advice for this? I need to allow them to weather as this is a historic site. Thanks for any input.