Heritage Restoration project at Dundurn Castle, Hamilton ON. Entry 1

Recently The Lime Plaster Co. began the process of restoring the plastered ceilings and walls of the front hall at Dundurn Castle, a Canadian national historic site. Unfortunately, the original lath and plaster system in this area has been interrupted over the years with the addition of a sprinkler system, the moving of the chimney breast, various repairs, etc. What this amounts to is a collection of different materials, all with different expansion rates on different substrates...needless to say, this makes things a little interesting!

 

To start off, our first order of business was to carefully consider exactly what we could and could not take out with the help from certain conservators and Hamilton city representatives. After this was established we moved forward by carefully taking out where possible, any foreign material (patches) for example where the sprinkler system had been installed. The holes left open by the installation of the sprinklers were covered with an expanding metal lath and covered with a high gypsum base coat. This is an inappropriate material for doing these types of repairs for a number of reasons. First being that it is far harder and less flexible than the original lime coatings so it wont act in the same way, leading to stress points within the walls and ceilings. On removal of the gypsum patches we have noticed that the wood lath underneath has been cut in no particular fashion which leaves a very weak substrate for the plaster to bond to.

  

Here at The Lime Plaster Co. we try to always use a 'like for like' approach when dealing with any of our heritage work, so for this reason we reattached new lath and gently tapped back in some tired old nails.

Once the areas requiring repair had been opened up it was time to prepare the new patch areas to receive our lime plaster mix. This process can be tricky and care must be taken to ensure that when the new material is applied, that it not only has a good backing to bond to, but the edges of the patch are flat so as not to leave a hump.

At present we have prepared the ceiling and 75% of the walls to receive our lime plaster material, so as we move along with this project we will keep you all up to date.