Architect: W. Garden Mitchell
Builder: P.H. Bosworth (San Francisco Concrete Building Construction Co.)
W. Garden Mitchell was a Scottish architect who began advertising for business in San Francisco in 1906. He was the author of several articles around that time, including being prominently featured in a article titled: "The Artistic Impression of Reinforced Concrete" (Architect and Engineer Magazine, Release IX, No.2, June 1907). In this article he promoted his views that the buildings should be covered in Stucco, Tile, and Mosaic or Marble.
Subsequently, Mr Mitchell designed the San Anselmo Town Hall, the San Anselmo Carnegie Library, and the San Rafael Christian Science Church. He passed away in 1918.
Paul H. Bosworth was granted two patents in 1908 (#944,594 and #927,215), both on an improved method of raising poured on-site, re-inforced, concrete buildings. Examination of some of the exposed concrete walls in this residence shows that these methods were likely used. Subsequent to this house Bosworth went on to build multiple other concrete residences and buildings. In the January 1911 edition of Cement and Engineering News, a promotional article was published stating "Mr Bosworth has done probably more than any other contractor towards making the concrete house attractive, sanitary, and within the means of every one wishing to possess a substantial residence at a moderate price". Two images of the Park Blvd. residence are included in this article. Subsequently, Bosworth himself wrote two articles in 1913 on concrete construction. His 1913 article in Concrete-Cement Age Magazine was titled "Flat Roofs for Concrete Residences" and features a picture of the roof of this residence.
One of Bosworth's patents detailed the use of front to back corrugated sheets of steel (making alternating sections of horizontal air gaps and solid sections). These pillowed sheets of steel were used as the reinforcing material, with the improvement over previous methods being the quicker building of concrete walls with enclosed hollow spaces (saving material cost for a given width of wall). This method is used throughout the Park Blvd residence. Corrugated sheets with pillowed air gaps were used; panels approximately 3 feet wide and 9 feet high are embedded in every wall, with a 1 foot gap between neighboring panels. It is unknown if this method was used on the roof, but the body of his 1913 article makes this a likely assumption.
While this method of reinforcing concrete has been replaced by more modern techniques, this approach seems to work well. The Park Blvd residence survived the 6.9 magnitude Loma Pieta earthquake of 1989 with no apparent damage. Normal winter-summer expansions and contractions often expose minor cracks in the walls and roof, but no structural problems have occurred.