The interior is a story of two halves; the first what you can see when you look up at the ceiling – its plaster work with its beautiful and unique features. Then what you can’t see, the timbers and structural framework which supports the ceiling –The support timber for the ceiling was visible to those lucky few that got access on the open days. A little history first- the roof was completed approx. 1830, but the ceiling was not completed until 1841.
The ceiling is almost totally self-supporting with a series of curved supports run vertical as about 3m centres and ribs run horizontally onto which the laths are fixed. As the ceiling is a separate structure to the roof there is a large attic space varying from 8’ to 20’ in different places.
Before any work to the ceiling could take place it had to be stabilised. This involved the installation of temporary supports from the roof to the ceiling ribs and vertical beams. Once the ceiling was secured the defective plaster and mouldings were removed. It was at this stage we learned more about the exact construction methods used. We had seen many variation and possible details in the reference manuals but until the works were opened up we were not certain of the exact details used. It turns out that large nails were driven in to the timber at the locations of the decorative beams and a twine/rope was twisted around the nails. This was an early form of reinforcement called pin and rope.
In order to replicate this detail a local Blacksmith Ray Munnelly from Rathlacken Ballina was sourced to make some nails to match the original work. This allowed the work to be replicated to the original standard and techniques. Each of the vertical beams was made of several pieces of timber glued together and cut to the profle of the vaulted ceiling. The arch of the ceiling has two radii /spring points. This means that the arc of the ceiling changes through out the celing. These pieces of curved timber were meticulously recorded and then Accoya beams cut to match the original shaped beam, the new beams were spliced onto the remaining beams and bolted securely into position.
Until now, using wood in damp external conditions for structural applications has been a real challenge, chiefly because of the risk of fungal attack. The most effective preservatives are by definition toxic and so have environmental issues both in use and disposal. While there are a few species of wood with good natural resistance to fungal attack, they are often difficult to glue and only have a comparatively limited life. Accoya offers the potential to use wood in completely new structural applications, formerly the preserve of steel and concrete.
Preservation of existing plaster and mouldings was essential and were removed from the defective areas infested by damp and fungus to protect them from any damage and allow any restoration work to begin.
Riven Sweet Chestnut Laths were installed as they were over 200 years ago, the material is cut and split from well-managed coppiced woodland, its irregular service of split grain is the traditional way to achieve a good key when installed for lime plastering. Here we used the original Lime plaster mouldings replicating exactly the same material and techniques as when the cathedral was first built.
As with all restoration projects, it was essential we used the same materials, a nail, something we take for granted had to made as they were then and used in conjunction with hessian twine to anchor the mouldings when put back into position. Handmade nails were used in conjunction with hessian twine to anchor the mouldings. The original moulding was anchored with 6″ handmade nails, these nails with a square profile to increase their pull-out resistance and we sourced these from a local Blacksmith, Ray Munnelly of Lacken.
There is 100’s of square metres of mosaic tiling, much of which was installed in the 1940’s, the survey had found many areas of boast or hollow tiles. This could have been caused by not enough adhesive under the tiles as this would leave hollow voids or it could have been caused by the wrong adhesive being used and it has not bonded in wet areas and has broken down. The only solution was record the areas identified with the tiles documented and then removed. Then the painstaking task begins of any single mosaic tile being cleaned and then refitted – there are approx. 2,100 tiles per M2!!!