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Researching the Fortress of Louisbourg National Historic Site of Canada
  Recherche sur la Forteresse-de-Louisbourg Lieu historique national du Canada




JANUARY 6, 1961

(Fortress of Louisbourg
Report H C 01)


One might have expected that the French would have protected at least exterior woodwork, such as doors and shutters, with paint. Surprisingly, not one word has been found in the documents so far to imply the use of paint either outside or inside the Chateau, although the presence of painters in the town is established.

Whitewash appears to have been the standard treatment for all interior masonry walls that were not sheathed in wood - two coats being specified. 


1. Exterior

By 1738, all exterior rubble masonry of the Chateau including the central passageway had been rough-cast i.e. all of the outside of the structure except cut-stone and brick ornamentation. The 18th century French documents refer to this treatment as "crepi à pierre apparente" which literally translates as rough rendering with the stones apparent. Upon the interpretation of that expression will depend the finished appearance of the Chateau. One conceivable hypothesis is that it means that the stones of the rubble masonry could be clearly seen - this would imply that the rough-rendering was actually nothing more than a massive re-pointing job with mortar. A more logical explanation might be that it is only the shape of the stones that it apparent. 

For description of early methods of rough-casting see General Consultant's report of June 23rd, 1962. 

2. Interior 

lnterior plastering consisted of either a one-coat or two-coat treatment. The base or rough-coat, which the French referred to as "crepissage et enduite en mortier" (literally, rough-rendering and finishing in mortar) seems to have been applied to all interior masonry walls. While this treatment was all that was intended for the walls of the soldiers' barracks, in the case of wing G, ground floor officers' rooms and the chapel, the "crepi et enduits en mortier" was only the base-coat for a finish-coat in lime plaster. 

Brick chimney breasts were also plastered, in conjunction with the walls, and the interior surfaces of all flues were plastered in mortar. Surprising as it may seen, there is a record of the stone dial of the clock having been plastered with lime in 1727. 


While some hardware, such as locks, was imported, much of the simple hardware was obviously produced on the job by blacksmiths. Lists of hardware, in iron, used by contractors on the Chateau include the following:

Iron was also used for the trammels of fireplaces as well as for some back-plates. Thirty of the latter were ordered in 1731 to be 2' 1 9/16" high by 2' 7 15/16" wide, while those secured in 1742 were 2' 3 11/16" high by 2' 11 1/8' wide. During the construction of the entrance bridge, 65 livres of iron were reported to have been used for braces, bolts and pins, 87 livres for bearings and 40 livres for chains and another 22 livres for other bolts. Iron was used in the making of the 3' 2 3/8" (3 pieds) high fleur de lys which topped the steeple.

Bars of iron were used as reinforcing in the construction of chimneys and fireplaces and there is some evidence from archaeology that iron cross-ties may have run the width of the building.


1. Stone

(a) Rubble-Stone

The Chateau St. Louis was essentially a rubble-stone structure, with the use of cut-stone and brick being confined, in the main, to ornamentation. Original specifications of 1717 forecast that one-half of the rubble-stone required could be found in the excavations i.e. the boulders contained in the glacial till. that could not be found on the site was brought from Port Dauphin.

(b) Flat-Stone (Pierre Plate)

This material was utilized for arches, for strengthening of the exterior corners of the wings behind the brick facing, for some paving and for chimney bases. Flat-stone was initially obtained near the Mira but in 1726 the contractor, Ganet, complained that he had to transport it 20 leagues to Louisbourg. It would appear to have been secured from shallow limestone beds. 

(c) Cut-Stone 

The cut-stone incorporated in the Chateau was produced from free-stone secured from a variety of sources at different times. Initially, native limestone was brought from L'Indienne, la Baie des Espagnols and l'Ile Justeaucorps. The Isle Royale stone proved unsatisfactory and by 1725 free-stone was being brought from France as ballast in the King's ships. Most of the French stone came from the Charente and much of it was sand-stone.

2. Marble

The tablet which was incorporated in the monumental gateway was of black marble which came from Anjou. 

3. Brick 

In the initial construction of the Chateau, the brick employed was of local manufacture, coming either from Port Toulouse or la Baie des Espagnols. It had the defect of being quite porous and scaled badly when employed on exterior work. New England brick, acquired by illicit commerce, gradually replaced the native brick as repairs were required. 

Standard size of French brick during the first part of the 18th century was as follows:

It has been previously mentioned that none of the Louisbourg specifications stipulate the type of bonding that was to be used in the laying of brick. A clue may exist in the fact that bricklayers from Flanders were imported to work on the Chateau - it may be that they used their own Flemish bond.

4. Mortar

The specified mortar mix for the masonry of the Chateau was 2 parts clean sand to 1 part slaked lime. Satisfactory results were seldom achieved due to the fact that the sand obtained from the beaches contained salt and this condition, in conjunction with the damp climate, retarded the set so much that stones often fell out of the walls months after they had been laid. 

5. Plaster 

Research has yet to discover specifications for the plaster used on interior walls or the technique of its application. Information is at hand concerning the standard lath century procedures for plastering but nothing specific for the Chateau St. Louis.

6. Wood 

The general specifications of 1717 for the Chateau stated that "Carpertry work on the barracks will be done in oak, birch, pine, white fir, that is the best type of wood that is to be found on the island." It was the undoubted intent that principal structural members should be of oak or an equivalent hardwood. Oak was, however, found to be very scarce and in actual construction pine, "merisier" and "sapin'' were often substituted. 

"Merisier", the English meaning of which is "wild cherry", was in actuality the local yellow birch which the French confused with their own wild cherry. To this day an important hardwood of Eastern Canada, it was often used instead of oak in the construction of the Chateau. In 18th century French usage, "sapin" - which translates as "fir" - was loosely used to refer to the woods of all evergreens, except pine. Where the use of "sapin" is indicated in the contemporary documents it is believed that the meaning is white, red or Eastern spruce, although the inferior balsam fir cannot be ruled out entirely. The variety of the pine used was not specified. 

By 1745, oak, yellow birch, pine and sapin were in use in the chateau, as follows:

(1) Oak 

(2) Yellow Birch 

(3) Pine 

(4) Sapin 

Where a structural feature has been omitted from the above listing (such as the great staircase of wing G), it is because the wood used was not indicated in the documentation.

It can be safely assumed that all heavy timbers, such as joists, purlins, trusses, king-posts, flèches, etc., were fashioned with the broad-axe. Planks and boards were the product of the whip-saw and would be hand-dressed by plane where indicated.

7. Slate

Slate for the roofs of the Chateau came from the regions of Nantes, St. Malo and Angers, i.e. upper and lower Britanny. It was almost black in colour.

Because slating was not contemplated when the original specifications were written, no size for slates is indicated. Lacking this specific information, recourse will have to be made to the typical 18th century French slate roof.

8. Iron and Nails

The initial specifications for Louisbourg stipulated that the iron for hardware, including braces, staples, hinges, pintles, bolts, keys, etc. would be of good quality and malleable i.e. of low carbon content. During the course of construction, it was reported that Canadian iron , from New France) was proving unsatisfactory and that the craftsmen would not work with it. Documentary evidence later establishes that iron was brought from Anjouleme in France and from Spain.

All nails were, perforce, hand-forged because the nail-cutting machine had not been invented when Louisbourg was built. Nail rods were used in making nails, producing a square, long and sharply-pointed nail with a roughly-flattened head. A big advantage of these hand-forged nails over the later machine-cut ones was that the earlier variety, being made of soft, low-carbon iron, withstood clinching without risk of snapping and were resistant to the acids present in oak timbers. Although there is a record of some nails being imported into Louisbourg in barrels, it is most likely that those used in the King's buildings were produced on the site. 

9. Lead 

Sheet lead was used for all roof flashings, including valleys, ridge and around chimneys etc. Lead was used also to secure the pintles of strap hinges or other iron work set into masonry.

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