Description – The model represents a former 18th century sheepfold near Honfleur, Normandy (France), which was later converted into a dwelling house. It is a fine example of a timber framed building typical of the Pays d’Auge region in Normandy. It was refurbished and partly enlarged in 2008, being not theme for our current inspection. This building demonstrates several stages of evolution: on the East elevation there are vertical studs and inside bracing; on the South-facing side there are oblique studs while in the front elevation double bracing has been used. In the 19th century more complex methods were introduced on the building like the St Andrew’s Cross or the ‘Épi et Fougéres”, which had much stronger bracing effect. As well as improving the building structurally, they were also more interesting aesthetically. Most of the studs were left loose without the use of wooden pegs. The timber frame materials originally came from local woods or from hedgerows (bocage). The walls between the timber frame had wattle and daub infill, while the roof was possibly thatched with straw in the beginning. The curved main rafters are made from either elm or oak. Their specific shape actualy follows the grain direction of the growing tree. They are essential components to stabilise the plate and provide a strong bracing effect.
Studwork and infill
In Normandy there were several traditional techniques used to fill the space between the timber frame elements to form a wall. You can inspect the different techniques applied on the different facades of the building.
Version 1 – ‘Torchis’ is a technique using local materials such as clay, mixed with straw or hay, to create a “daub” or “cob” infill. The cob fills in the gaps between the timber studs to restrict water and draughts entering the building. The straw or hay is mixed with the clay to prevent the clay cracking as it dries. Even so, there is some shrinkage when the clay dries out, and regular maintenance and attention to repairs is needed to prevent the infill deteriorating.
Version 2 – ‘Tuileaux’ is technique using small (often broken) tiles with lime mortar. The outside surface was usually kept without plaster, forming a very decorative wall together with the bracings. It is a time-consuming process, and often reserved for higher quality houses.
Version 3 – Adobe or clay bricks. Another traditional infill technique seen in timber framed buildings in Normandy is the use of fired (or sun-dried) clay tiles or bricks laid to fill in the spaces between the timber posts. These are laid using lime mortar, often to arranged to form a decorative facade.
Version 4 – ‘Hempcrete’ is a modern technique that allows for better heat insulation. It is made from chopped hemp fibres mixed with a lime-based mortar. Because of the usage of local natural materials, low amount of embodied energy and good insulation value it is considered to be an effective “ecological” building material.
1. Bridle joint, with a tie beam head – In this example the tie beam is being used in tension. This ensures that the opposite walls are strengthened and prevented from falling away from each other. To achieve this the tie beam had to be lifted above the height of the wall before installing the end plate. Carpenters developed lifting devices to raise heavy timbers.
2. “Through Tenon” with single, or double key – This solution is often used in restoration to secure two posts and prevent them falling away from each other. The beam is working in tension, and the external part of the tenon is locked with pegs to prevent the joint from sliding out of the mortice.
3. The haunched tenon joint – This is an adaptation of the simple tenon to allow a smaller mortice hole to be used where there is a risk of weakening the timber post.
Haunched tenon used for lintel – The lintel is cut shorter on the top face, that on the bottom of the horizontal lintel. The lower face of the tenon rests on the base of the mortice. The lintel must be placed between the two posts before they are pushed in to place.
Haunch for the Sole Plate – In this case the tenon is cut longer on the top face than on the bottom. This reduces the risk of water penetrating the joint, and improves the durability of the post.
4. The Stud Tenon joint is usually cut to retain the central 1/3 of the width of the piece of wood. The length of a tenon differs according to its location.
5. The “Bastard Tenon” or Barefaced Tenon is a simpler form of mortice and tenon joint where the tenon is not cut in the centre, but just on one side. This involves fewer cuts to achieve the joint.