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A centuries-old construction method, the wood-broom pan, little or poorly protected from the rain, deteriorates more or less rapidly. A renovation "in the tradition" is always possible. The mixture of old and modern techniques is sensible for greater durability.

Restore a half-timbered wall

An assembly of materials

The piece of wood is an assembly of pieces forming a framework. In the voids of this frame, a filling of bricks, tiles, rubble, clay, mud, which ensures the insulation of the wall. This type of construction is found in almost all regions (Alsace, Burgundy, Normandy, Picardy...). The wood-broom pan is the most common technique. Built on a basement masonry, the frame consists of poles and scarves (oblique pieces of wood) set in two low and high horizontal beams, called sandpits. A lattice laid between the woods serves as a support for the mud, a mixture of clay and a vegetable binder (straw, hay...). The poles and scarves, more or less spaced, define panels of different widths, which take the name of half-timberings if they remain visible after application of the mud.
In any case, such a construction must be sheltered from the weather, otherwise the mud crumbles. But even if a stone base and a roof overhang protect the wall from the splashing of the rain, the wood pan always ends up deteriorating if it is not maintained regularly. A complete renovation is inevitable.

Repair the frame

To repair or replace weakened pieces of wood, it is first necessary to remove the daub and lath to expose the framing. It is possible to restore the damaged pieces of wood without disassembling everything.
After carefully supporting the timber framing and the interior of the house, brushing the half-timber shows the rotten wood to be repaired or replaced. It is necessary to take advantage of the exposure of the frame to realize an insecticide treatment and general fungicide.
The damaged parts are replaced by beams of equivalent section, recovery if possible. The assemblies (tenons mortises, half-wood, false tenons...) are copied to the identical.
If the basement no longer has sufficient strength, it must obviously be renovated. Either by joining the stones or bricks, or by building a new wall.

Observe the condition of half-timbering and erosion

Observe the condition of half-timbering and erosion

The daub of the half-timbering facing due west did not withstand the weather. The splashing of rainwater at the foot of the basement eroded the stone grouting.

Coated or coiled

The technique of the mud differs from one region to another. It comes from the know-how of some craftsmen, even farmers who pass on their technique from generation to generation. Easier, for everyone, a coating applied on a brick filling can replace it.
The application of a cob is done in three layers. The first one, called coarse or coarse cob, is the filling material between the wooden sections. It is composed of a mixture of clay soil, sometimes sand, and straw or hay mixed with water. It is applied coarsely and thickly on the lath fixed between the elements of the stud. After drying, two coats of finishing plaster are applied. The first consists of clay soil and small straw. The second, plated and smoothed, of the same composition, is reinforced with aerial lime (CL or DL).
The lathing between the woods can be replaced by bricks on which is laid a plaster. Natural and healthy material, the clay brick built with lime mortar and coated is a waterproof, insulating wall that lets breathe timber timber and weatherproof.

Compare the condition of wooden beams

Compare the condition of wooden beams

After removing the daub, support the stud, not forgetting to put struts in various places inside. Examine the woods to determine which ones to keep, repair or replace.

Replace and prune wood

Replace and prune wood

Remove rotten or damaged posts. Replace them with gas beams and identical section. With the saw, cut the tenons according to the mortises of the upper sand pit.

Fix the posts

Fix the posts

Introduce and tilt the post to insert the post into the mortice of the sand pit. A wooden peg will consolidate the assembly. The bottom of the pole will be fixed on the floor by brackets.

Redo the stone bedrock

Redo the stone bedrock

Sort the basement stones according to their thickness and group them by row. Then climb them row by row on a bed of bastard mortar (1 part cement, 1 lime, 6 sand).

Paste rows of bricks with mortar

Paste rows of bricks with mortar

Mount the bricks with bastard mortar. Plant a few points in the posts at the joints to reinforce the half-timbering. Check verticality as you mount.

Apply a first coat of plaster

Apply a first coat of plaster

Moisten the brick wall 24 hours before application. With a trowel, project a thick layer of lime plaster (Parex, PRB, Weber & Broutin...). Tighten to the rule.

Apply the second layer

Apply the second layer

4 to 5 days after the first coat, apply a second one that comes to the bare woods. Flick according to the desired finish. Use the same plaster to grout the foundation stones.


Video Instruction: Repairs to a timber frame