Water Tight

There is a gap between the cast iron water tank on top of the tower and the stonework below.   The weight of the tank is taken by iron girders the ends of which rest on the walls.   Cast iron and stone expand and contract differently so the gap needs to be filled with a sealant which allows for this movement.   The size of the gap varies between 1mm and 30mm.

The gap had once been filled with cement, the failure of which let in a great deal of water which inevitably soaked in to the tower walls or ran down the inside of the building.

When restoring the tower we filled the gap with builders silicone which worked for a while but that too failed as it hardened and could not cope with the movement between the iron and the stone.

We needed a sealant which could bridge wide gaps and had much more elasticity than silicone.  Enquiries led us to ArboMeric MP20 - a one part high modulus modified polymer sealant which cures on exposure to moisture vapour to form a tough but elastic rubber.

Super gloop, it seems to have done the trick.