Lime Plaster & Breathable Building Conservation
LIME PLASTER & BREATHABLE BUILDING CONSERVATION
PROJECT JOURNAL
St Andrew's Church
Timberland
LINCOLNSHIRE
Traditional lime plaster repairs to a damaged lath and plaster ceiling
When I first visited St Andrew’s Church, sections of the roof above had failed and water had found its way through to the old lath and plaster ceiling below.
A large area of plaster had already fallen away, while an even bigger section had started to lose its hold on the timber laths.
The first job was to work out what could sensibly be retained and what would need to be removed before the ceiling could be repaired properly.
Scaffolding was erected beneath the damaged area and, with the help of a labourer, I began carefully taking down the loose plaster while trying to preserve as much of the original lath as possible.
Removing the loose plaster was the least enjoyable part of the whole project.
I’ve taken down plenty of old ceilings over the years and they’re never particularly pleasant jobs, but this was one of the worst I’d encountered. There were no opening windows in the work area, so I brought along a dust extractor in an attempt to draw in some fresh air and remove some of the dust. In truth, it didn’t feel like it made a great deal of difference.
We started at one end of the ceiling and slowly worked our way across, carefully removing the failed plaster while retaining the laths that were still in good condition.
We were almost finished when, through the dust, I could just make out the silhouette of my labourer waving his arms frantically at me.
We’d uncovered a beehive.
We scrambled down the scaffolding and left.
The following day it was time to apply the first coat of haired lime putty plaster.
The scratch coat is worked through and around the laths so that it forms a mechanical key behind them as it sets. Once the coat had been applied, I scratched a diamond pattern into the surface to provide a good key for the next coat.
I was working alone, which meant getting all of the plaster up onto the scaffold, mixing it in a plasterer’s bath and then applying it overhead across the ceiling.
By the end of the day I was fairly pleased to see the back of it.
A week or so later, once the bees had been safely removed, I returned to clear the remaining rubble and begin preparing the ceiling for plastering.
The original laths that were still sound were cleaned down and retained. Where sections had become too damaged or brittle to reuse, I replaced them with hand-split oak laths, matching the existing construction as closely as possible.
This was the point where the job began to feel less like demolition and more like repair. With the ceiling cleaned back and the damaged areas made good, it was ready for the first coat of lime plaster.
Around ten days later, once the scratch coat had sufficiently cured, the ceiling was ready for its second coat of plaster.
Having learnt my lesson from the previous visit, I persuaded my friend Dean to come along and give me a hand. I first worked for Dean nearly twenty years ago when I was an apprentice, and we still occasionally work together now.
It completely changed the day. For the first time on the project I actually enjoyed myself, and from there the job felt fairly plain sailing.
Together we applied and ruled the float coat, building out the ceiling and leaving a good, even surface. This was then floated with a devil float to give the plaster a good key for the final lime finish.
A week or so later I returned on my own to apply the final fine lime putty top coat.
After the heavier work of the previous visits, it was a much steadier day.
Once everything was cleaned down, I packed up my tools and headed home.
Wherever possible, the original fabric of the ceiling was retained, with new material introduced only where it was needed.
It was a relatively small repair in the context of an old church, but a good example of why these buildings are worth repairing with materials and methods that belong to them.