It depends. The piano is a complex instrument, with over hundred individual strings and thousands of moving parts. Each string must be painstakingly adjusted to put the piano in tune. Even the tiniest change in a string's tension can be heard by a practiced ear.
You might think, then, that trucking a piano down the highway or even rolling down a hall could “knock it out of tune.” However, pianos are actually quite tough. They're built to withstand up to 20 tons of string tension and decades of heavy usage, so the physical movement of a piano usually has very little effect on its tuning or other adjustments.
It's the climate change associated with the move, rather than the actually move itself, that makes pianos go out of tune. A substantial difference in humidity between its previous location and its new home will change the shape of the piano's soundboard, changing tension on the strings.
For instance, a well-tuned piano moved fifty miles from a heated, dry apartment to a cool, humid home will sound fine immediately after the move. But a week later, after adjusting to the higher humidity, the piano will sound out of tune. Even moving a piano from one room to another in the same building can affect it if heating or air-conditioning patterns are different.
An exception is he vertical piano. Because they have four casters (grands have three), they occasionally flex enough to distort there tuning pattern immediately if moved to an uneven floor. Moving the piano back to a flat surface will return the tuning to normal. This is most noticeable with light built spinets and consoles, and can occur simply by moving the piano a few inches if one caster rolls off the carpeting or into a low spot on the floor.
So, do you have to tune your piano after moving it? Pianos need periodic tuning anyway, whether they are moved or not, so it's likely that a piano that has just been moved was already due for tuning before the move. If so, it's best to let the piano adjust to its new environment for a week or two, then have it tuned. On the other hand, if the piano had been recently tuned before the move, you might just hold off and see how the piano sounds after a few weeks. If the climate of the new location is similar to the old, your piano will probably sound fine until its next regular service date.
You might think, then, that trucking a piano down the highway or even rolling down a hall could “knock it out of tune.” However, pianos are actually quite tough. They're built to withstand up to 20 tons of string tension and decades of heavy usage, so the physical movement of a piano usually has very little effect on its tuning or other adjustments.
It's the climate change associated with the move, rather than the actually move itself, that makes pianos go out of tune. A substantial difference in humidity between its previous location and its new home will change the shape of the piano's soundboard, changing tension on the strings.
For instance, a well-tuned piano moved fifty miles from a heated, dry apartment to a cool, humid home will sound fine immediately after the move. But a week later, after adjusting to the higher humidity, the piano will sound out of tune. Even moving a piano from one room to another in the same building can affect it if heating or air-conditioning patterns are different.
An exception is he vertical piano. Because they have four casters (grands have three), they occasionally flex enough to distort there tuning pattern immediately if moved to an uneven floor. Moving the piano back to a flat surface will return the tuning to normal. This is most noticeable with light built spinets and consoles, and can occur simply by moving the piano a few inches if one caster rolls off the carpeting or into a low spot on the floor.
So, do you have to tune your piano after moving it? Pianos need periodic tuning anyway, whether they are moved or not, so it's likely that a piano that has just been moved was already due for tuning before the move. If so, it's best to let the piano adjust to its new environment for a week or two, then have it tuned. On the other hand, if the piano had been recently tuned before the move, you might just hold off and see how the piano sounds after a few weeks. If the climate of the new location is similar to the old, your piano will probably sound fine until its next regular service date.