Granite chapel construction:

Ben Alder Chapel

Ben Alder Estate, Highlands · 2009

Our role: Masonry sub-contractor: granite and lime masonry
Client: Stewart Milne Construction (main contractor)
Architect: Trembath Associates
Value: Over £2m
Programme: October 2007 to December 2009
Scope: Coursed granite rubble walling, dressed granite quoins, windows, doorways and arcades, lime mortars, precinct and terrace walls, spire, internal lime plaster and limewash

The chapel at Ben Alder Estate stands on a remote Highland site beside a loch, near Dalwhinnie. Designed by Trembath Associates, it is a new building with the character of a traditional church: a granite nave and transepts, a Romanesque porch, a slated roof, a tall spire and a crenellated precinct wall. Our work was the granite masonry, built in lime mortar so that the chapel would look and weather like a historic building.

Ben Alder Chapel, Ben Alder Estate, near Dalwhinnie, Highlands — photograph 1

Ben Alder Chapel, Ben Alder Estate, near Dalwhinnie, Highlands — photograph 2

Ben Alder Chapel, Ben Alder Estate, near Dalwhinnie, Highlands — photograph 3

Ben Alder Chapel, Ben Alder Estate, near Dalwhinnie, Highlands — photograph 4

Ben Alder Chapel, Ben Alder Estate, near Dalwhinnie, Highlands — photograph 5

Ben Alder Chapel, Ben Alder Estate, near Dalwhinnie, Highlands — photograph 6

The challenge

The structure is a steel frame on a concrete foundation, clad in a cavity wall with a traditionally built granite outer face 290 to 300mm thick. The site is exposed and remote, and the programme meant working through winter, outside the season normally accepted for lime mortar. The design called for a large quantity of dressed granite: quoins, window surrounds, doorways, internal pillars and arches, a rose window and the spire. At the outset there was no masonry specification, so the mortar mixes and the method had to be developed for the job and tested.

Our solution

A weathertight shed was erected over the building site, which allowed lime mortar to be used through the winter in controlled conditions. Mortars were designed with an independent materials consultant: hot lime mortar made from NHL 3.5 quicklime and sharp granitic sand for the rubble, stronger mixes above roof level and on exposed elevations, and finer mixes for dressed work. Mortar was mixed on site at a hot lime mixing station and checked with sample cubes and carbonation tests. The outer face was built in reclaimed squared granite rubble with new granite dressings, over a blockwork inner leaf with a drained and vented cavity. Dressings were cut to drawings and cutting sheets for each element, including buttresses, gables, eaves caps, doors, windows, internal arches and the spire. Inside, granite pillars and arches carry the nave arcade and chancel. Outside, the work extended to the porch, the crenellated terrace and precinct walls and the gate entrance, and finished with the spire. The internal lime plaster and limewash were added to our package on the architect's instruction as the chapel went up.