Architectural Investigation


We can look at a structure and make assumptions about what it was used for and how it got there but it may not be accurate. In order to understand a structure we have to look at all of the individual pieces. Architectural investigation is a process where each piece of the structure is studied for it’s relationship to the entire structure or site. It is only when all the pieces have been studied that one can begin to understand the process of how the structure arrived at it’s current condition and it’s intended use.

Important pieces shown here are the grade stamps found on the lumber in the Kitchen area of the main cabin. Grade stamps provide information about the quality of the lumber but they can also help date the lumber. These pieces were stamped by the West Coast Lumberman’s Association at a mill site operated by Santiam Lumber Company in Lebanon, Oregon. According to an official at WCLIB, the Santiam Lumber Company’s association with WCLIB and the use of this stamp began on August 19, 1941.

The stamped pieces of wood appear in locations of the cabin that would indicate they were installed at the time of original construction. One of the roof boards in the Kitchen is covered on the top side with roofing paper and when the surface is exposed it appears to have been covered ever since it was nailed into place as a new piece of wood. Since these grade stamped pieces were not available until sometime after August, 1941 suggesting the earliest beginning date of construction for this portion of the building.

The cabin has three rooms I will refer to as the Living Room, Bedroom and Kitchen. Of these rooms the living room was first to be built as a stand alone structure. It is apparent by the nailing pattern where the living room and bedroom are joined. The nails on the adjoining side of the living room could only have been installed before the bedroom was added. Knowing this sequence of construction helps to determine the development timeline of the site.

The first room, the living room, is constructed similar to a pole barn. Utilizing lightweight materials, the wall studs directly support the 1”x8” roof rafters. Each wall stud and roof rafter also employed a 1”x4” angle brace to give it additional support against horizontal forces. Each roof rafter was cut with a gentle arch at the top and each end set into a notch cut into the top of a 2”x4” wall stud. The roof sheeting, rather than using wood, was actually wire window screen with roofing paper laid over it. The exterior wall covering appears to have been 1”x6” boards with tar paper and slat trim for wind and water protection. The Living Room is also observed to have a cement foundation and floor. It was laid flat and well tooled as shown below. The surface spalling is evident only due to the years of being covered with linoleum, dirt and freezing water.

It is possible there were two different builders working on the structure. The two photos on the left appear to show a slight variation in carpentry ability . The photo to the left shows the angle bracing in the living room offset in each bay creating a staggered line. Generally this is not the method used by a skilled carpenter. The angle braces in the kitchen and bedroom walls were installed consistently in a straight line as shown in the lower photo. This is a preferred method of installing this type of bracing. This difference could indicate two different builders were involved with the construction and possibly at two different time periods.

The bedroom and kitchen were of an entirely different construction design and were built as one addition at a later time. The floor was built of wood and rather than an arched roof cut from 1”x8” boards, the roof rafters were installed by a method known as a ‘cut and stack’ to form a Gable roof design. It is the most common kind of roof design, a simple sloped roof with a high point at the center, known as a ridge,  running the entire length of the building. The builder was skilled to accurately cut all of the rafters at the exact angle and even attempted the proper ‘birds mouth’ seat cuts required for this type of roof design.

With regard to craftsmanship and carpentry style the photo on the left is a detail of the wall top plate at a roof rafter bearing point. The wall top plate splices are consistent and neatly cut. Rafter cut is also neat but I do not believe by an experienced carpenter. Though the rafter is sitting flat on the wall plate, the ‘birds mouth’ seat cut is too deep and as a result the full depth of the rafter is not supported. It’s necessary to differentiate the many carpentry techniques used in the construction of this cabin as it could identify the possibility that this builder was unique or that he possibly built other cabins in the area.

Ceiling height in the cabin appears to be quite low since most of us have become accustomed to the current standard of 8’. The cabin does appear to be built on what I will call a 6’ standard. That is to say, all of the lumber in the cabin is 6’ or less in length. I am not sure why, though I can think of several reasons. Hauling materials to the site on pack animals is certainly simplified with shorter materials. Also, in the construction industry as a conservation method, lumber and sheeting materials are sized according to their use, for example the 92 1/4” length of common wall studs will allow for an 8’ 3/4” wall height when top and bottom plates are installed. No cutting required or waste created. This in turn allows for an economic installation of 4’x8’ sheets of plywood and drywall, also without any waste. Given the fact that the cabin is sheeted with 3’ wide tar paper tells me that a 6’ high wall would eliminated any waste of this material. Roofing paper would also be conserved by keeping the rafters at just under 6’ in length. I should also note that I have yet to bump my head on any ceiling in the cabin and as we all know, the higher the ceiling, the more it takes to keep it warm.

There is a variety of dimensioned and rough sawn lumber that was used for the top and bottom plates, wall studs, roof rafters and sheeting throughout the cabin. Some of the wood appears to have been painted before it was installed. It was not uncommon to salvage material from an abandoned site and use it to build at another location. Additional lumber would be purchased to supplement the materials needed and that is where the grade stamped lumber gives us a pretty good idea that the bedroom and kitchen were added onto the Living Room after August 19, 1941. Given the amount of time it would take for graded lumber to be processed and travel from the Santiam Lumber Company I am guessing this portion of the cabin was built sometime very near the end of 1941 or early 1942.

There is still much to be investigated. These are just a few of the observations and there is still much more to do. Documenting details of construction, review of other nearby sites for similar methods and materials and continuing the research in county records for “proof” assessment reports. Until all the research has been completed any conclusion will be subject to correction.


To see videos of the Japanese Camp main cabin please follow this link to Video Documentation. Please note that these are very large files (35MB) and will require a high speed connection to load.

For detailed information about Architectural Investigation and Preservation

see the Preservation Brief provided by the National Park Service at


Putting Together the Pieces

In 1923, the WCLA (West Coast Lumberman’s Association) formed the first national committee for lumber standardization. They are now known as the WCLIB (West Coast Lumber Inspection Bureau) providing grading and inspection services.