In message , Helen Findlay
writes
There has been no work done to the house in at least five years.

The floorboards upstairs in some areas seem looser and move noticeably when
walking over them

Easily fixed with a few screws or nails.

and downstairs there is a slight incline where they seem
lower than the rest of the room. Not hugely but I have noticed this over
the last few months.

Hmm, that could indicate a problem with the joists - such as some rot at
the end where it is supported by the wall.

I'd lift a few boards and have a peek

--
Chris French, Leeds