Shakes and asphalt shingles are like apples and oranges; they're very different. Shakes are made from wood and have natural, rustic beauty that appeals to many homeowners. However, they will need regular resealing, or they may develop premature leaks.
Asphalt has a more modern appearance and can vary in color to complement the house. Asphalt shingles are durable and easy to maintain. They have a relatively low price; asphalt shingles cost around $150 per square, and last around 20 years. Asphalt shingles vary in price depending on the quality and type.
By contrast, shakes are costlier, $600 per square, and depending on the type of wood used, may last somewhat longer (30 years).
You can buy roofing shakes from roofing supply merchants who carry wood roofing materials. You may, however, get a better price if you let your roofing contractor procure the shakes for you, as they can often get them at trade prices. Still, be sure to shop around to see if you can find a better deal. Just remember to check the grade of the shakes so that you don't end up with common grade when you wanted straight grain.
Cedar shakes roofs can last up to 50 years if they’re 100% straight grain shakes and properly installed and maintained. However, after 30 to 50 years, you'll need to have them replaced. Signs you may need to replace your shake roof also include:
Leaks
Water damage
Curling shakes
Split shakes
Moss
Rot
Missing shakes
Yes, you can wash cedar shakes and shingles with a power washer. You can use pressure washers, too, along with appropriate detergents. Power washing gets rid of algae, mold, and general dirt and detritus. It helps to bring the color back to your cedar roof, blasting away the grime and bringing your cedar roof back to its original look.