Bridge at Ormiston House by Kirknewton, West Lothian
The semi circular single arched masonry bridge which is understood to be C listed and in the order of 150 years old provides the main vehicular access to Ormiston House.
The bridge had been allowed to deteriorate and the maintenance was overdue. Many defects were apparent to most of the visible elements and we raised suspicions that additional hidden problems could exist. From our inspections carried out, it became clear that weathering and attack by vegetation had continued relatively unabated and that this had given rise to an acceleration of deterioration to the point where extensive structural repairs were urgently required.
The aspiration was to achieve a stable structure that is basically water tight, with joints that are filled with mortar and do not allow vegetation to grow and attack the masonry with disruptive expansion of root growth. It is also about achieving a structure from which water sheds, rather than seek to penetrate and also contribute to attack of the bridge. Localised defects such as potentially vulnerable parapets merited attention and of paramount attention was the integrity of the voussoir stones, the wedge shaped stone units forming the soffit of the arch. In order of priority, attention was focused on the integrity of the arch itself, followed by the spandrel walls and then the rebuilding of the parapet walls.
Scope of Works
- Parapets on both sides were taken down and rebuilt level and aligned.
- Sections of the Spandrel walls where bulging was taken down, infill material excavated and walls rebuilt incorporating weep holes to disperse water.
- Timber arches were erected to support arches to both sides of bridge, defective arch stones were carefully removed and replaced with new stone to match existing.
- Delaminated areas of Edinburgh stonework under the bridge were carefully removed and replaced with new stone to match existing.
- With the bridge being a listed structure, repairs were undertaken in the appropriate manner using traditional materials.