1. It's Been Too Long Since the Last Tuning
This is the most common cause by far. A piano that hasn't been tuned in two, three, or five years doesn't just drift a little — the overall pitch drops, sometimes by a full semitone or more. When a tuner brings it back up to concert pitch (A440), the enormous increase in string tension causes the frame and soundboard to shift and settle. Within weeks, some strings slip back.
This isn't a fault with the tuning — it's physics. The solution is a pitch raise: a rough first pass to bring everything close to pitch, followed by a fine tuning once the piano has settled. Sometimes a second fine tuning is needed a few months later. After that, the piano stabilises and holds normally as long as you keep up with regular tuning.
What to do
If your piano hasn't been tuned in over two years, expect that the first tuning may not hold perfectly. A follow-up tuning 3–6 months later will lock things in. After that, annual tuning keeps it stable.
2. Humidity and Temperature Swings
This is the big one in Ireland. The piano's soundboard — a large, thin piece of spruce — is the heart of the instrument, and it responds directly to moisture in the air. When humidity rises, the wood swells, the soundboard pushes upward, and the strings tighten. When humidity drops, the board flattens and the strings go slack.
In an Irish home, you get both extremes in the same year. Summer brings damp air. Winter brings central heating, which dries the air out rapidly. Every time your heating clicks on in October and off again in April, your piano's soundboard goes through a significant dimensional change. That's two guaranteed shifts per year, and in older Dublin houses with poor insulation or draughty rooms, it can be worse.
What to do
- •Keep the piano away from radiators, fireplaces, and exterior walls.
- •Avoid placing it near windows that get direct sunlight.
- •Try to keep the room at a reasonably consistent temperature and humidity — a hygrometer costs a few euro and tells you where you stand.
- •Consider a piano-specific humidity control system (like a Dampp-Chaser) if your home is particularly variable. These sit inside the piano and regulate moisture automatically.
- •Tune twice a year — once a few weeks after the heating goes on, once after it goes off. This catches both seasonal shifts before they compound.
3. Worn or Loose Tuning Pins
Each of the roughly 230 strings in a piano is wound around a tuning pin — a steel pin driven into a laminated hardwood block called the pinblock (or wrest plank). The pin holds the string at the correct tension purely through friction.
Over decades, the holes in the pinblock can enlarge slightly, or the wood can dry out and lose its grip. When this happens, the pins can't hold tension reliably, and the piano slips out of tune within days or weeks of being tuned.
This is more common in older pianos — particularly those over 40–50 years old, pianos that have lived in very dry environments, or cheaper instruments where the pinblock was made from lower-quality wood.
What to do
A tuner can assess your pinblock during a standard appointment. If a few pins are loose, they can sometimes be driven slightly deeper or replaced with oversized pins. If the pinblock is failing across the board, the realistic options are a full pinblock replacement (expensive, only worth it on a high-quality instrument) or accepting that the piano has reached the end of its practical life. Your tuner will be honest with you about which applies.
4. Old or Damaged Strings
Piano strings are under enormous tension — collectively around 15 to 20 tonnes across all strings. Over time, strings lose elasticity and develop false beats — a subtle wavering in the sound caused by uneven wear along the string's length. Old strings don't vibrate as cleanly, and this can make even a well-tuned piano sound slightly off.
Broken strings are more obvious — you'll hear a dead note or a rattling sound. Individual strings can be replaced straightforwardly, but if many strings are deteriorating, a full restringing may be worthwhile.
Rust is another factor, especially in Ireland's damp climate. If you see visible corrosion on the strings, particularly on the plain steel treble strings, they're losing both tonal quality and tuning stability.
What to do
Individual broken or badly corroded strings can be replaced during a tuning appointment. If the piano's strings are generally old and dead-sounding, ask your tuner whether a restring would be cost-effective for your particular instrument.
5. Structural Issues
Less common, but worth knowing about. The piano's cast iron frame (also called the plate or harp) bears the full tension of all the strings. In rare cases — usually from impact damage, manufacturing defects, or extreme age — the frame can crack. A cracked frame cannot maintain stable tuning and is generally not economically repairable.
The soundboard can also develop cracks, though these are more common and often cosmetic rather than structural. A cracked soundboard doesn't necessarily mean the piano can't be tuned — many pianos with minor soundboard cracks play and hold tuning perfectly well. A tuner can assess whether a crack is affecting performance.
Bridge problems — the bridge being the wooden strip that transmits string vibration to the soundboard — can also cause individual notes or sections to sound wrong. Cracks in the bridge, or bridge pins that have come loose, affect both tone and tuning stability in that area of the keyboard.
What to do
These are assessment-and-advise situations. A good tuner will spot structural issues during a normal appointment and give you an honest evaluation of whether repair is practical.
How to Tell If Your Piano Needs Tuning Right Now
A few quick signs:
- ✓ Playing a simple chord (like C-E-G) sounds harsh or "beating" rather than smooth.
- ✓ Notes in the middle of the keyboard sound fine, but the top or bottom octaves sound noticeably off.
- ✓ The piano sounds different from how you remember it — duller, thinner, or just wrong.
- ✓ You can hear a wavering or wobbling quality when you hold a single note.
- ✓ It's been more than 12 months since the last tuning.
If any of these apply, your piano would benefit from professional attention. The longer you leave it, the further the pitch drops, and the more work (and cost) is involved in bringing it back.
The Bottom Line
Most tuning instability comes down to two things: irregular tuning schedules and uncontrolled humidity. Fix those, and the vast majority of pianos will hold their tuning reliably between annual or biannual appointments.
For the mechanical causes — loose pins, old strings, structural issues — a tuner can diagnose the problem during a standard visit and advise you on what's worth fixing.