Distillers may need to expand a part of their process equipment, for example to add more washbacks, giving more capacity before replacing a mash tun, or adding a pair of stills.
The re-organisation may be to facilitate more visitors, or to make a tour more logical.
This is the work I have carried out for Dingle Distillery. We were very careful to not ruin the kooky nature of the visit, whilst moving grain handling, tun and washbacks up into another building, and opening up walls to give window views over the coast.
The seaside face of DIngle... no windows
The hand filled mash tun!