Squeaky floors upstairs

Very rarely. Opening a finished ceiling is disruptive and usually unnecessary, because there are from-above methods that reach the subfloor connection through the floor itself with a small point of entry that is repairable and largely invisible. We would only suggest ceiling access if the cause turned out to be something a from-above fix could not reach.

It is, and it is a normal characteristic rather than a mystery. Sound travels along a joist, so a connection loosening at one point can be audible several feet away, and where you hear it downstairs is often not directly beneath where somebody is standing. That is why we locate these with one person walking and one person listening rather than by guesswork.

It muffles the surface sound a little but it does not address the cause, because the movement is happening in the subfloor connection beneath the flooring, not in the flooring surface. Adding carpet over a squeaky floor is a common suggestion and a common disappointment. It is cheaper in the end to fix the connection and then choose your flooring freely.

Concentration of traffic. Every trip between bedrooms, the bathroom and the stairs crosses the same few feet of hallway floor, so those subfloor connections are worked far harder than the ones under a bed or a wardrobe. Hallways and landings are the first place we look in a two-storey house.

Only in that it explains why you noticed. The repair is the same, but knowing which room below is affected helps us test properly, because the whole point is that somebody sitting in that room stops hearing it. We will ask you to sit downstairs while we walk the floor before we call the job done.