SIGA 120

SIGA 120 Augustine United Church

Project Name: Augustine United Church, Edinburgh

Slate Supplied: SIGA 120

Roofing Contractor: B&D Roofing

Re-roof of church roof, 500m²

Project Overview
The Augustine United Church built in 1861, is a richly decorated, distinctive and unusual building, built in a mixture of architectural styles.  The church is located on George IV Bridge in the heart of Edinburgh’s Old Town and just minutes from the Royal Mile.

The church roof had reached the end of its lifespan and needed to be replaced. A new roof would not only add to the beauty of the church but also facilitate improved insulation, assisting with energy conservation.

This significant project was funded by the Heritage Lottery Fund, Historic Environment Scotland and Allchurches Trust.

The roof of the church was originally covered in Ballachulish Scottish slate, but the Ballachulish quarries are now extinct and an alternative slate was required to complete the work.

SIGA 120 was specifically commissioned by B&D Roofing to meet  conservation requirements and because it replicated the aesthetic of the original roof perfectly.

In Detail
In 1955 the last Scottish slate quarry closed and since then, no new Scottish slate has been produced.  Scotland’s historic buildings have had to rely on salvaged slates for repairs and restoration.  Good quality second-hand Scottish slate has become increasingly difficult to source.

The church could have tried to re-use existing slates, but it is likely they would have lost in excess of 50% in the process. To make up the difference, they would have had to source a supply of matching second-hand slates. Taking this approach, it is highly likely the outcome would be a roof that looks somewhat second-rate, because the smaller slates would be too small, and a proportion of the slates will be not quite up to the same standard.

In general Scottish slate is coarser grained than others and as a result the roofing slates are thicker and more irregular than for example, their Welsh counterparts. This has resulted in random sized slates of differing thicknesses laid in diminishing courses, giving Scottish roofs their distinctive appearance.

Although Ballachulish slate is very durable, the slates on the Augustine United Church were very old and had reached the end of their service life making them impractical to re-use. The Church required 500m² of replacement slates and with such a large quantity it was not possible to rely on second-hand Scottish slate to maintain the visual integrity of the built environment. As a listed building the original character of the church needed to be maintained.  An alternative needed to be sourced, matching as closely as possible, the colour and dimensions of the original slate.

Laying random slate is a highly skilled and traditional process requiring great care and skill.  SIGA 120 was selected as the best and closest match to the original slate. SIGA 120 is a new Welsh blue/grey slate which is being quarried to replicate the diminishing courses on the traditional Scottish roof. SIGA 120 is currently produced in a range of sizes which are roughly equivalent to those produced in Scotland’s Ballachulish Quarry in the 19th century and still found on countless roofs today.

A further benefit of using SIGA 120 compared to using reclaim slate, is the reduction in time taken to sort through, trim and size second hand slates, and for the building owner, the assurance that the re-slated roof will endure for generations to come.

SIGA 120 slates are fully traceable, with a quality standard that second-hand slate could never hope to match. As such, these new slates are fast becoming a popular alternative to the most commonly used Scottish slates and were the perfect choice for the Augustine United Church.

Augustine Church For website 2

Project Outcomes
The Augustine United Church roof has been restored to its former glory with a stunning outcome, using a high quality slate which is as close to the original aesthetic as possible.

Traditional Scottish slate techniques were used to lay the roof, which retains its distinctive diminishing courses.

SIGA 120 is a real alternative to Scottish slate meaning that countless historical buildings can be restored without having to rely on reclaimed slates which are difficult to source and likely to be towards the end of their service life.

This prestigious building has a new roof which is in keeping with its heritage, replicates the beauty of Scottish slate and will last for generations to come.