According to the publication Installation, Care, and Maintenance of Wood Shake and Shingle Siding, for direct application, shakes or shingles are applied directly over properly installed and flashed Type 30 felt (or house wrap as approved by local codes). Shakes and shingles may be single-coursed, stagger-coursed, or double-coursed. The double-course application permits the use of a lower grade for the first layer and a greater exposure of the higher quality second layer of shake or shingle. Pressure-impregnated preservative-treated products can be used in these applications.
With some knowledge and skill, shakes can also be applied over existing siding.
Shakes and shingles may be used to cover existing wood beveled siding, masonry, or stucco. The shakes or shingles can be applied directly over the existing siding; however, rain screen application is necessary over brick, stucco, and foam sheathing. If applied directly over composite wood siding products such as hardboard siding, use longer fasteners and nail through the siding to the underlying sheathing. The brick molding around windows and doors will have to be extended, so it may be better to increase the wall thickness even more and use the rain-screen application. Fasten vertical furring strips to the underlying wallstuds, fasten horizontal boards to the vertical strips, and nail the shakes or shingles to the horizontal nailing strips.