Stabilising the Curtain Walls

The last time we saw Alasdair Smith (right) and Liam Martin of UKdima Engineering Ltd at the castle, they were drilling two large holes through the basement rock from the moat into the castle to carry the services, including the heating from the biofuel boiler.  They've been down again over the last few weeks, this time drilling much smaller holes through the bases of the curtain walls as part of a process of stabilising the walls.

The method is very similar to that used to pin the huge granophyre blocks in place when work first started on the castle, with forty-two steel reinforcing pins being inserted through the bottoms of the walls, from the outside into the courtyard, epoxied into place, and then plates placed on either end and screwed tight to pull the two sides together.

This plan shows a vertical view through one of the curtain walls. Blocks had to be removed from the exterior (left)....

....and the hole drilled through the base of the wall.

The steel rods were then inserted, and steel plates screwed tight on either end.

Later, the rocks that had been removed were replaced and mortared into position so the plate is hidden.  The mortar here has yet to be brushed, so it will quickly blend in with the rest.

When I went down to the castle today, a small team, including Richard (pictured), was working on the base of the walls, the one place where the pointing hasn't been completed.  Until recently, the scaffolding wasn't in place to make it accessible.

The lowest section of the west wall is now almost complete, but they have to work their way round all the other walls.  Here's hoping that the weather holds so that this, one of the last jobs that have to be done on the exterior walls, can be completed as soon as possible.  Then, some time after New Year, the scaffolding will come down and the refurbished and strengthened walls will be revealed.

Picture of steel plate courtesy Mark Thompson.