The "Murphy" "XLA" "Flexible" "Outside Metal" Roof

Murphy XLA on a Minneapolis & St. Louis USRA design 40-ton double sheathed box car. Jack Delano photo, Chicago and North Western Proviso Yard, FSA-OWI Collection, Library of Congress

 During the 'teens and into the early 20s, the most common roof design on house cars was the "Murphy" roof. The roof went by many names, including Murphy and Murphy XLA as used commonly by hobbyists, as well as Outside Metal and Flexible Outside Metal. Standard Railway Equipment Co. was the primary purveyor, although it seems likely that it would have been licensed as needed. 

Car Builders' Cyclopedia page illustrating the Murphy XLA roof design

Seemingly everyone with even a casual interest in freight cars is aware of this roof design and could easily point it out on models. What is less well known and is the reason for this post, is how the roof actually worked. But first, modelers who replicated this design, especially scratchbuilders, typically took sheet styrene and added strips at the correct (or incorrect!) spacing to simulate the battens. What is frequently overlooked, yet is easily modeled, is the lip at the eaves that was part of the design's effort to mitigate water seepage.

Detail from an L&N box car drawing illustrating some of the details of the "Murphy Improved Pivoted Outside Metal Roof"

Back to the prototype... the edges of the roof sheets, batten coverings, peak coverings, etc., incorporated pressed, rolled edges that interlocked in such a way that it would be difficult for water to enter the seams and joints. In a static setting, this was probably quite a good solution. However, the forces imparted on railroad cars over years of service could result in areas of leakage. Likely by design, the roof seemed to be quite serviceable, meaning any issues could be resolved in the shops.

The arrows in the image above highlight the "lip" as described in the text. One other note is that the leftmost panel with an arrow (second from car end) is narrower than the other panels. This was not uncommon and is something to watch for in your modeling efforts. Klamath Falls, Oregon, FSA-OWI Collection, Library of Congress

Returning to modeling... the overlap of interlocking roof sheet and flexible eave can easily be simulated by making the roof slightly "short" at the edge and adding an abutting strip. The battens over the roof sheets can continue over the strip, simulating this detail. It is something I have added to such efforts once I became aware of it. A roof without this detail could be fixed also, by making an angle of an appropriate depth piece of styrene that "sits" in the appropriate distance, allowing you to lightly scribe lines between the battens. One interesting detail is that the batten strips do not seem to be uniformly designed. Some appear to extend almost to the edge of the roof eave while others terminate more midway between the lip of the roof sheets/flexible eave and the angle of the eaves. Happy modeling!

This car, a Milwaukee Road prototype, also illustrates different width panels on the roof. Jack Delano photo, Milwaukee Road Bensenville, Illinois Yard, FSA-OWI Collection, Library of Congress

The image shown above is my creation of the XLA roof with the flexible eave added using a styrene strip. It is discernible at the outer roof edge, at the eaves. This is from a resin part from a styrene pattern that I created for another project, but was easy to add here once I separated the one-piece Tichy sides and roof into their component pieces by carefully scribing and snapping.