The cill beam is potentially the most vulnerable member of the frame - possibly one of the most important. Investigations for decay in the cill must be thorough, as evidence of a defect comes to light quite gradually. Cills can appear to be sound, when in fact they have decayed from the inside. Movements at the stone plinth or the sinking of a single post can indicate that a cill has decayed. There is then usually little option but to replace the cill beam. Specialist advice is required to assess the options for repair, but generally the operation is well understood.
The lack of structural determination of such frames makes them vulnerable to inappropriate alteration, and surveyors must be wary of any evidence which suggests that spans have been inadvertently increased, or beams or posts removed.
The significance of the need to tie together the component parts was not always understood, and often remedial work is needed to stitch elevations and horizontal structures together. Gable ends are also vulnerable to leaning, if not braced into the roof structure.
Movement in timber buildings is more readily accommodated within the frame if lime mortars and timber wattle infill allow some flexing to take place. The characteristic 'crooked cottage' is usually caused by wear of sap wood at the joints and gradual seasoning of differing cuts of timber. Evidence of cracking needs to be assessed with this in mind, as it may be that these cracks allow the stresses in the structure to dissipate. It can be a mistake to remedy such cracks with a form of rigid repair, as this can over-stress other parts of the building.
Most frames require cross-bracing (which is sometimes visible). Later additional walls may be acting as bracing walls holding the building square. If these become affected by rot, the whole frame can start to twist.
The cill beam is potentially the most vulnerable member of the frame - possibly one of the most important. Investigations for decay in the cill must be thorough, as evidence of a defect comes to light quite gradually. Cills can appear to be sound, when in fact they have decayed from the inside. Movements at the stone plinth or the sinking of a single post can indicate that a cill has decayed. There is then usually little option but to replace the cill beam. Specialist advice is required to assess the options for repair, but generally the operation is well understood.