Rocky Mountain House National Historic Site of Canada

Fur Trade Wood Construction Techniques

The most constant occupation for labourers at a post like Rocky Mountain House, was working with wood. Such essential tasks as collecting and hauling wood, chopping firewood, squaring timber, sawing boards, and repairing and constructing buildings must have seemed endless. Post structures varied considerably from large, more permanent buildings such as storehouses and officers’ quarters, to such temporary structures as the log “tents” that sheltered post hunters at many northern posts. Buildings with different purposes required different construction methods and materials. Though various construction materials and techniques were evident at fur trade posts across North America, the most prevalent was the use of squared logs to construct post on sill (or “Red River Frame”) buildings. 
 

Palisades/Post in Ground

Palisades were a common feature of early fur trade posts, though over time they diminished in importance. By the mid to late 19th century the palisade had become more a symbolic than genuine attempt at fortification at many posts, often taking the form of a low fence. Yet palisades continued to be used into the late 19th century in areas where some protection was deemed prudent.

The main method for building palisades at Hudson’s Bay and North West Company posts in the late 18th century and through most of the 19th century was a technique known as post in ground (also known as “en pile” or “poteaux en terre”). The post in ground method required portions of the wall to be laid out on the ground alongside of a trench dug in the soil. When a section of wall was ready, the round or squared timbers were placed upright and side-by-side in the trench, which was then refilled with soil in order to hold the timbers.

The upright timbers could be reinforced with horizontal timbers forming a reasonably stable wall -- although one that was prone to rapid decay, especially along the soil line and at the tops of the pickets. Certain woods, such as tamarack, were more resistant to decay. But the woods typically available for palisades showed serious signs of rot within 5 to 10 years at best. Most modern images of fur trade posts show palisade walls with pointed tops, which would have helped shed water and thus delay rotting of the pickets. However, some (perhaps most) of the larger fur trade posts chose rather finish the tops of palisades by cutting them off level and adding a top, flat board to protect the exposed ends of the pickets. Some walls were strengthened by the addition of larger upright timbers, called king posts, which were buried more deeply than the intervening pickets. The palisade walls at the reconstructed Fort Edmonton are a good example of this building method.

Post in ground buildings were constructed in New France and in other areas of Canada. In the book, Building Canada An Architectural History of Canadian Life (Toronto: Oxford University Press, 1966), Alan Gowans describes this as a “Stone Age” building method because of its simplicity. Post in ground buildings were found at some posts, though they were not the most common form of building construction in the fur trade.

Post on Sill / Red River Frame Construction

Post on sill construction provided a more durable structure than post in ground and other simpler building techniques. This was particularly true if the sills were placed on a stone foundation raising them above the soil line. Known variously as Red River frame, Hudson’s Bay frame, “poteaux et piece coulissante” (post and sliding piece) or “pieces sur pieces” as well as post on sill, this technique was admirably suited to construction in the fur trade. It could also be adapted to use stone fill – a technique known as “colombage” used, for example, at Lower Fort Garry.

Post on sill construction required few tools (basically a broad axe, adzes, chisels, hammers and occasionally augers or drills, as well as a felling axe to cut the timbers in the first place). It could be used quickly and relatively easily to build structures of varying sizes. Because it did not require complicated notching or fitting of logs, existing buildings could be extended and altered without having to start all over again. Post on sill buildings were not only easily remodelled or repaired, but they could also be disassembled and moved as needed. Another main advantage of this building method was that because the lengths between posts were relatively short, the cross pieces could be made from lower-quality wood that might otherwise have to be discarded.

In post on sill construction, large squared timbers were used as sills to lay out the basic configuration of the structure. Upright posts were mortised into the sill logs, usually about 2 metres or 6 to 7 feet apart. The posts were cut with a groove on two sides (at 90 degrees for corners and 180 degrees on walls) and the spaces between these upright posts were filled with squared timbers. These wall timbers were tenoned at either end allowing them to slip into the grooved uprights. An auger or drill could be used to drill through the logs from above allowing the insertion of wooden pegs to pin the logs together and add stability, but this was not required and would be rare at most posts.

Doors and windows were added using smaller uprights or by placing them against a major post. Walls were then finished with a top wall plate. A roof could then be attached to the wall plates. Typically these were steeply pitched gable or hipped roofs (to shed snow) made from boards or bark.

In the interior of the fur trade buildings, floors could be left as dirt or lined with wood by laying wood flooring onto large “sleepers” or horizontal timbers placed on the ground. The sleepers could be attached to the building frame, but often they were placed independent of the walls creating a form of “floating” floor.

The use of squared timbers meant that buildings constructed using post on sill methods were relatively weather-proof. They did not usually have the kind of gaps between logs that are typical of log buildings constructed with round timbers. Nevertheless, most were finished by adding chinking to fill gaps and often a layer of “mud” – particularly if they were intended as housing – to improve their insulation. Some later post on sill buildings were also finished with board or other types of siding.

Tools and Tasks

Surviving fur trade journals describe the various tools and tasks required in cutting timber, squaring logs and sawing boards for post on sill buildings. Timbers were squared for construction using a broad axe, a smaller axe for scoring the wood and, if desired, an adze to further smooth and shape the timber. The standard technique of squaring timber was to walk along the length of it striking the wood every few centimetres at a right angle, scoring the bark and outer wood. The axes used for this were usually smaller than broad axes, though in a pinch any axe would do. This left the log with the characteristic tool marks of slightly angled vertical cuts. The timber was then squared by using a broad axe cutting parallel to the log to remove chips. This would be done around the log four times to create four reasonably flat sides to the timber. An adze could then be used to further smooth and shape the timber.

A inventory list of building tools from Jasper House in 1856 includes an interesting array of wood-working tools including “Carpenter’s foot adze,” “Screw and Shell augers,” “Large Square head axes,” “Braces and bits,” “Boxhead and Spike gimlets,” “Carpenter’s claw and clench hammers,” “Plane irons,” as well as assorted files, chisels, rasps, saws, wood screws and planes (Source: HBCA, B60/d/118, Saskatchewan District Inventory, 1856.)

To make buildings warmer and less drafty, chinking was added to stop up the inevitable holes and gaps between roughly squared timbers. In some cases buildings - especially those used for housing – were covered in whole or part by a coating of mud or clay. This provided a smooth finish which could then also be whitewashed. In a few cases at larger posts, sawn boards were used to cover the building as “siding” instead of using mud.

Sawing Lumber

In addition to squared lumber, swan lumber was needed at fur trade posts for various purposes. Sometimes it was used to line the inside of buildings or to create walls within structures. Sawn lumber was also good for flooring. At Rocky Mountain House much of the sawn lumber was used to build York boats or bateaux. The post journals regularly refer regularly to men cutting boards at a pit saw across the river.

The simplest saw pit was not a pit at all. Instead, large timber could be sawn on heavy trestles or very large saw horses. Unfortunately, this did require manhandling the timber onto the trestle -- hard work that could be avoided by building a pit or using a natural hollow. Even with a pit, you would need a frame to support the log being sawn. Usually saws were designed to cut on the down stroke, so the lower man in the saw pit pulled the saw, while the upper man lifted the blade up and out on the upstroke.

Other Log and Wood Construction

While post on sill buildings were versatile and enduring, some fur trade structures were highly temporary. The log tent is an interesting example of the kind of temporary structures built by fur traders. Used in the boreal forest areas as housing for company employees and their families at hunting and fishing camps, it used cut logs placed at an angle against a ridge pole. The structure could then be covered in mud to produce a reasonably weather-proof, but very simple form of housing.

Examples of other types of log construction can be found at fur trade sites, particularly in the later 19th and early 20th centuries as new building methods and materials became available. Without seeking to review all the various forms of log construction, examples of saddle notch, dovetail and other methods of building log structures can be seen at fur trade posts across Canada. In addition, in some areas commercial building materials had become available by the later 19th century and examples of frame buildings with clapboard and other forms of siding can be found at fur trade sites.

Sources and Further Reading:

A good general source on log construction around the world is Hermann Phelps, The Craft of Log Building (Ottawa: Lee Valley Tools, 1982). There are also numerous general surveys of log building and architecture in Canada. John Rempel’s Building with wood and other aspects of nineteenth-century building in Ontario (University of Toronto Press, 1967) is a pioneer in the field. See also Peter Moogk, Building a House in New France (Markham: Fitzhenry & Whiteside, 2001). Fur trade architecture and building methods is also the subject of many Parks Canada research reports.