Restoration of a 15th-Century Timber Barn: Structural Stabilisation and Subsidence Repair

This project involved the careful refurbishment and structural stabilisation of a late medieval timber-framed commercial barn of approximately 500 sqm. The building exhibited progressive movement attributed to long-term subsidence, localised ground softening, and deterioration of primary load-bearing timbers at low level.

Initial Assessment and Movement Analysis

A full structural survey identified differential settlement along the north and east elevations, with the most significant movement occurring in two central bays. The original oak sole plates had suffered advanced decay due to prolonged ground moisture exposure, resulting in a loss of bearing capacity and uneven load transfer into the primary post-and-beam frame.

Secondary deformation was observed in the form of racking within several bays, with slight rotation in the principal tie beam assemblies. While the upper frame remained largely intact, the lower structural zone had effectively become the failure point of the building.

Temporary Works and Stabilisation Strategy

Before any permanent intervention, a full temporary propping system was installed internally to arrest further movement. Adjustable steel acrow props and spreader beams were used to support the principal load paths, allowing controlled redistribution of forces during repair works.

This phase was critical in isolating the unstable ground-bearing elements while maintaining the integrity of the historic frame above.

Installation of Load-Bearing Plinth System

Given the extent of timber decay at ground level, a decision was made to introduce discreet concrete plinths at key structural nodes. These were positioned directly beneath primary posts following careful laser-level survey work to re establish correct datum lines across the structure.

Each plinth was cast in reinforced concrete and finished below ground level where possible to minimise visual and environmental impact. A separation layer was introduced between timber and concrete using breathable isolation pads to reduce moisture transfer and allow for minor seasonal movement.

The original posts were carefully jacked and re-aligned before being lowered onto the new supports, effectively transferring load away from compromised sole plates while preserving as much historic fabric as possible.

Timber Repair and Frame Reconstitution

Where sole plates and lower post sections were beyond repair, targeted timber splicing was carried out using seasoned oak, matched in species and grain orientation to the original fabric. Traditional scarf joints, reinforced with concealed stainless steel fixings, were used to maintain continuity of load transfer while ensuring long-term durability.

In several bays, minor realignment of braces and secondary members was undertaken to correct historic distortion caused by uneven settlement.

Final Structural Outcome

The completed works successfully arrested ongoing subsidence and re-established a stable load path throughout the structure. The introduction of discreet concrete support elements, combined with traditional timber repair techniques, allowed the barn to retain its historic character while achieving modern structural reliability.

The building now operates as a hybrid system: a preserved medieval timber frame supported by a carefully engineered foundation strategy designed to respect both the material limits of the original construction and the environmental conditions of the site.

Site Manager Roy Holland : "It was nice to work on a very unique and traditional building, the detail and extent these old building were built to is incredible, the team enjoyed saving the structure for years to come"

Subsidence works enquires:

James Williams

info@avendale.co.uk

0207 971 1488

www.avendale.co.uk

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