Coxton Tower Restoration Work

However twelve months later the roof is worse than ever. The motar used to repoint the cracks did not last as well as expected.

The Problem was that the earth between the stones was holding the water but since the stones have parted from their original tight fit, the the water is coming through more than ever, especially on the North facing roof that does not have the sun on it so much.

Moray Council who helped last time, are no longer giving grants but Historic Scotland are funding some of pahse 2 to the project.

The work that has been done for phase 1 is taking off all the roof and then putting it back properly. Re-harling is part of phase two of the project, as well as replacing the windows and other internal work that started at the end of July 2008.

In 1995 the Coat of Arms over the door cleaned up. This meant cleaning the sandstone and using a preservative on it.

Work started at the end of May 2001, on phase 1 of the project. Laing Traditional Masonry, who are now based at Castle Fraser but were Lhanbryde based at the time, were contracted to do the work, although the first few days were spent with Speyside Scaffording Services, errecting the scaffolding. Another company who were involved, was Grants of Dufftown, who were the plumbers repairing the guttering for example. We had new guttering all round, The circular bartizans had to have guttering specially made, using a stensil to ensure correct fitting.

Prior to any work being undertaken, a full photographic record of stone ridging and flagstones were mapped on drawings, numbering accordingly. The flag stones were then uplifted course by course, marking the top of the slab and angle of the slope where they butt against the crow steps, chimney stack or circular bartizans to ensure each stone was relocated like for like. These were then cleaned and stacked at the base of the scaffold in order of sequence and sequence of uplift.

The masonry sub-base forming the barrel vaulting was of rubble stonework built in lime mortar, which was washed of all its lime binders leaving a friable aggregate substrate contaminated with soil and high vegetation content. All loose material was removed by way of vigorous scraping with trowels and stiff bristle brushes until a firm base was found. All vegetation was extracted with isolated areas of dismantling and deep root treatment necessary to remove and kill off root vegetation. The prepared sub-base was primed with St Astier natural hydraulic lime 3.5 limewash to consolidate and reintroduce a lime rich binder to the sub-base prior to rebuilding of roof slabs.

The mortar for the bedding of slabs was a hybrid mortar with a composition of Cloddach, well graded concrete sand mixed with quick lime as a hot mix to give a mortar matching the original, whis gauged with St Astier NHL for duability

A mortar composition of:-

20 parts Cloddach concrete sand

3 parts quicklime

2 parts NHL 5

This consisted of:-

20 parts Kirkhill building sand

3 parts quicklime

2 parts NHL 5

The stone slabs were uplifted and laid on the scafford a course at a time measuring the overall length of course against the running dimensions of the roof, assessing the number and thickness of each vertical joint and ensuring an even space between each slab.

A Sting line was tightly fixed at opposite gables on the crow steps where the top of the slab meets the angle of slope previously marked, allowing the exact relocation and bed heights of the slabs.

All mortar beds and joints were pressed back firmly tamping to within 10mm from face stonework as the stones were rebuilt, ensuring consolidation and good preparation for the final pointing. This was then protected with occasional dampening down for a minimum duation of ten days to allow the well-tamped mortar to carbonate.

Existing cementitious mortar and unsound lime mortar was removed from the joints and beds of the bartizans, crow steps and chimneystacks, tamping with line mortar and protecting in conjunction with the works being undertaken on the roof slabs.

Clashach sandstone chimney copes were installed to replace the existing weathered and damaged copes on 3 chimneyheads. Replacement stone copings were dressed to match existing exactly in dimensions and profile. Existing chimney cans were replaced with a new capping system to allow ventilation and protection to the redundant stacks. The venting caps were place on top of the new coping and secured in position to the chimneyheads with stainless steel brackets projecting down internally into the chimneystack ensuring future easy access.

After sufficient curing time of the recessed tamped mortar, a final pointing using the above bedding mortar was applied, finishing flush to allow mimimum obstraction to rainwater runoff. The mortar was beaten with a bristle brush to give an open, stippled texture, ensuring maximum carbonation an an aesthethically pleasing finish.

Before	After