There were several strange modifications to the rooms in which both of the Roylott ladies resided. The fact that there was any work going on at all at the house was immediately suspicious:
Some scaffolding had been erected against the end wall, and the stone-work had been broken into, but there were no signs of any workmen at the moment of our visit.
As the Roylott estate was no longer wealthy, and the rest of the building was in disrepair, it was odd that any work should be done at all. And, if there were necessary repairs, there were no workmen to complete them.
Holmes then identified the unusual adaptations to the house. His first concern was the ventilation system:
There are one or two very singular points about this room. For example, what a fool a builder must be to open a ventilator into another room, when, with the same trouble, he might have communicated with the outside air!
Secondly, Holmes observed that the recently installed bell-pull served no discernable purpose and did not work. His third concern was the positioning and modifications to Miss Roylott’s bed-
"It was clamped to the floor. Did you ever see a bed fastened like that before?"
Holmes surmises that the adaptations have been made to facilitate Grimesby Roylott's evil plan and, of course, he is right.