Sandstone windowsills ,old house, the butted joints eventually open up what is the best compounds to fill in these gaps. I have large window on front with 3 butted joints opened up, and 3 smaller ones at rear same fitted in two pieces instead of one.
I think the house was made from scavenge bits left over from the other parts of this estate. Tried cement but eventually that falls out due to not adhering to sandstone.
Many thanks in advance