Denver, South Park and Pacific Railroad

The Double-Board Roof

John Maxwell's plans for some DSP&P house cars have the notation "double-board roof" so it appeaars likely that most were built with this kind of roof. Early cars may have had a single-board roof at first.  All of Ron Rudnick's drawings of DSP&P house cars show wood-board roofs.

Since the large scale commercial models lettered for DSP&P have a form of metal (Murphy) roof, I wanted to backdate the roofs on my cars to represent the 1885 era, well before metal roofs were in common use. The first Murohy metal  roofs didn't appear until 1906 and photos of C&S era cars show no evidence that these or similar roofs were ever applied.

Below is the reasearch that I could find on the Internet on the subject of wooden roofs, followed by my solution to retrofit wood roofs to large scale models.

Some Board-Roof Definitions
Four general styles of roof construction were used in the 1880's on boxcars and refrigerator cars:
             1: the double-board roof
             2: the single board roof covered with tin or other sheet metal
             3: the sheet metal roof protected by a single layer of roughly matched boards
             4: a double roof consisting of an inside roof covered with felt, tar paper or asphalted canvas and
                 an outside roof built over it to protect the roofing material from injury.

 Ridge pole -- runs the length of the car along the centerline, under the roof, forming support for the
           peak of the roof.

Purlins or purlines -- beams that run the length of the car, spaced between the ridge pole and the
  exterior wall of the car to support roof boards.

Carlines or carlings -- beams that run from the car side wall to the ridge beam, acting like rafters, to
  support the purlins, which in turn support the roof boards.

Double board roof -- two layers of dressed 1x6 lumber, with grooves to shed water, running from the
  ridge pole to the car sides, painted before installation and overlapped so that joints are offset from one
  layer to the neaxt.

Single board roof -- a single layer of boards as above but covered externally by tarred canvas or
  sheet metal, or with sheet metal underneath with or without tar paper or tarred felt between.


NOTE: on a self-supporting metal roof, such as the Murphy patent roof, the carlines are outside the roof, not underneath, and act as both support for the roof and as a water-tight seal at each panel joint. There are no interior caelines or purlins, thus giving an unobstructed interior to the car. Panels and carlines were galvanized to resist corrosion. The panel joimts and carlines were riveted, and later welded, to form a "uni-body" roof.

Research Results - Double Board Roof
The double-board roof was  the most common, well into the 1900's, but had disappeared on new construction in favour of all metal roofs by the early to mid 1920's.

As quoted on the Pacific NG website "In the construction of this roof only the best seasoned white pine boards should be used. A common practice is to use boards dressed on both sides and edges to a uniform size of about 7/8 x 5 1/8 inches and have two semi-circular grooves of 5/8 inch diameter on one side, near each edge. (running the length of the board). The purpose of these grooves in the top course of boards is to catch and carry off as much of the water as possible, keeping it out of the joints; these same grooves in the under course catch and carry off such of the water as penetrates the joints of the top course. As the grooves in the under course are apt to become clogged with dirt sometimes the two courses are placed in contact so as to increase the size of the channel for carrying off the water. The boards of both courses are nailed to the plates, purlines, and ridge pole.  The edges and faces of the boards are always heavily coated with paint before they are laid. The pitch of the roof varies from 1 to 2 inches rise per foot. The steeper the pitch the better the protective qualities of the roof but the more dangerous to trainmen who have to pass over it."


Cross-section of the two styles of double-board roof. It is not known which was used on DSP&P cars. Only the version shown at the top of the image is given in the Car Builder's Dictionary of 1879 and 1888. Note that the grooves are not at the edge of the boards, as they are on V-groove tongue-and-groove siding.  I used Bachmann simulated wood roofs to replace the Murphy style metal roofs on my large scale DSP&P house cars, as shown later on this page.

Another drawing of the double board roof, an out-take from Robert Stears drawing of D&RG reefer #119.

Research Results - Single Board Roof
The single-board roof became more common in the late 1880's and early 1900's. It typically used wooden roof strips over each joint in the boards and had metal inner roof to keep out the water. There were many variations on the theme as car builders progressed toward the self supporting metal roof.

The single-board roof was made of T&G 1" x 6" boards without V-groove edges. Some had metal above the boards, some had metal below, some had roof-strips covering each joint. Cross-section above from the 1887 Car Builder's Dictionary shows 1. roof strip, 2 metal sheet underneath boards, 3. roof ridge pole, 4. purlin parallel to roof ridge, 5. car side-wall sill, 6. roof boards. I have never seen anyone model roof strips and most models show V-groove boards.


Example of the Double Board Roof

This is UPD&G boxcar 25192 on the ground near DSP&P tracks at St Elmo near Aloine Tunnel in 1948 after more than 50 yeasr of weathering and modification as a shed. The sawed-out roof area shows construction details including the near-side purlin rumming legthwise halfway between the car wall and ridge pole. Photo from "Narrie Gauge Pictorial" Vol VIII.

Closeup of the roof hints at the double board construction along the lengthwise saw cut near the roof ridge. A carline is also visible under the purlin, and the interior roofing below that.







A Double Board Roof Solution for Large Scale Models

The Murphy patented "outside" metal roof didn't arrrive until 1905 so no DSP&P car could have carried one until well along in C&S service. Converting the poorly rendered Murphy roof on the LGB, Delton, and USA Trains reefers and boxcars to a simulated wood roof makes a huge difference. The cure is to purchase some well used Bachman 933xx series boxcars at auction and snap off the roof - it is simulated wood, and the only one available in large scale. It needs to be shortened a bit in a miter saw to replace the Delton and USA Trains roof, and shortened even more for the LGB cars, then it just snaps into place. A little glue makes it semi-permanent. LGB boxcars have the top door track molded into the roof, so you will need to steal door tracks as well as the roof, and glue them in place before installing the roof.

After you steal the roofs from the Bachmann boxcars, what do you do with the leftovers? Remove the trucks, underframes, steps, grab irons (both sides and ends), and the doors and door tracks (one side only). Glue two cars side-to-side, add a platform, stairs, freight, barrels, people, signage, and (of course) a new roof. Here I used three of the LGB roofs to make the two needed replacements. You could use simulated corrugated iron or shakes, depending on your taste. The trucks, or at least the wheels, from the Bachmann cars are probably better than some on your older rolling stock, so use these spare parts to upgrade, or for another kitbashing project.