A Story From the Field: The Rehearsal Room That Fell Silent for a Week

Teacher Phum runs a small music school and instrument shop in a shophouse off Pracha Rat Bamphen Road in Huai Khwang. The ground floor is the shop, with acoustic and electric guitars and ukuleles hanging on the wall and digital keyboards on display. Behind it are a piano room with two upright pianos and a band rehearsal room lined with acoustic panels, fitted with a drum kit, amplifiers and wall-to-wall carpet. Upstairs are a violin studio and a music theory classroom. Most students are primary and secondary school children who come after school and on Saturdays.

During the heavy rain of October 2026, water in the lane rose and flowed into the ground floor to about mid-shin, staying for four days. Teacher Phum and his staff carried almost all the guitars and keyboards upstairs. The two pianos, however, were far too heavy to lift. The drum kit and the large amplifiers could only be raised onto plastic crates, and the carpet and lower acoustic panels in the rehearsal room were completely submerged.

When the water receded, the rehearsal room had the worst smell in the building. The carpet had soaked up water and smelled foul. The lower acoustic panels had discolored and were dotted with black spots. The piano legs and lower wooden panels bore water marks, and when he opened the piano lid he could see condensation inside. A couple of real-skin drum heads were showing white mold spots. Within a few days, even the guitars hanging upstairs started to pick up a musty smell, because humid air had drifted up the staircase.

Parents began calling to ask when lessons would restart. Some were worried about children with allergies and asthma. Teacher Phum knew that a rehearsal room sealed tight to contain sound is just as good at containing moisture and mold spores. He also knew that the expensive instruments in the shop are both assets and the working capital of the business. Rushing to reopen without the right approach would put both the children's health and the instruments at risk.

His school is not the only one. Music schools, rehearsal studios and instrument shops across Huai Khwang, Din Daeng, Sutthisan and Rama 9 are facing similar situations right now.

Why Music Schools and Rehearsal Rooms Are Especially Prone to Mold

Rehearsal rooms are designed to be sealed for sound isolation, which means they have far less ventilation than ordinary rooms. Walls are usually lined with acoustic foam, synthetic fiber panels or fabric-wrapped boards, and floors are often carpeted. All of these materials absorb moisture readily and dry very slowly. The instruments themselves are made from wood, leather and felt, which are sensitive to humidity to begin with. When relative humidity stays high for several days, wood swells, glue joints can weaken, and mold starts to grow on unfinished surfaces such as the inside of guitar bodies and the underside of piano keys.

A music school also has a very particular pattern of use. Rooms are closed most of the day and then filled with students in the late afternoon and on weekends. That means humidity builds up in empty, closed rooms for hours at a time, and then many people, often children, breathe that air in a short, concentrated period.

Health risks for students and teachers

• Mold spores and the respiratory system. Children with allergies or asthma may sneeze, become congested, cough or have difficulty breathing in a room with airborne spores. Wind instrument students, who breathe deeply as part of playing, may be especially affected.
• Germs from floodwater. Carpets and floors that were submerged may be contaminated with bacteria such as E. coli. Young children who sit on the floor during group lessons have direct contact.
• Leptospirosis. Wear boots and gloves during clean-up, because the bacteria enter through cuts and scrapes.
• Instruments that touch the mouth. Recorders, harmonicas and mouthpieces for wind instruments that were in floodwater must be cleaned and disinfected according to the manufacturer's guidance before use.

Damage to the business and the instruments

A music school earns its income from ongoing courses. If it stays closed for long, students may move to another school and not return. An instrument shop carries high-value stock that is highly sensitive to humidity. A guitar with a warped neck, a piano that has drifted out of tune or developed sticky keys, and a drum with moldy heads all reduce the value of the stock and the confidence of customers.

Spots that are easy to overlook

• Behind acoustic panels mounted flush against the wall, where moisture is trapped.
• Beneath rehearsal room carpet and its underlay.
• Inside the piano, particularly the lower panel and pedal mechanism.
• Instrument cases lined with velvet, which hold moisture even when the instrument itself has dried.
• Cabinets on the ground floor that store sheet music and method books.
• Cable drawers and the backs of amplifiers, where dust and humidity combine.

Common Fixes That Can Cause More Damage

Drying wooden instruments in the sun. Damp wood exposed to strong heat dries unevenly and can crack, warp or lose glue joints. Wooden instruments should be brought back to normal moisture levels gradually in a room where humidity can be controlled.

Wiping with bleach or strong alcohol. These can mark lacquer finishes, dry out and crack drum heads, and damage felt.

Running fans in the rehearsal room. Fans help remove humidity but also spread spores from the carpet and acoustic panels onto other instruments.

Spraying air freshener. Fragrance covers the smell briefly, but damp carpet and acoustic panels remain a breeding ground for mold.

Running high-concentration ozone through the whole room without removing instruments. High ozone concentrations can affect genuine leather, rubber, felt and certain components in instruments and electronics. Dose must always be controlled, and valuable items must be moved out first.

An Instrument-by-Instrument Guide Before Any Treatment

The most important principle is simple: treat the room, and let qualified technicians treat the instruments. Ozone and fogging are tools for air, odor and surfaces, not a substitute for an experienced luthier or piano technician. The notes below will help you decide what to move, what to cover and who to call.

• Acoustic guitars, ukuleles and violins: remove from the treatment area. Keep them in a dry room with stable humidity, out of their cases if the cases are damp, and have a technician check necks, bridges and glue joints.
• Electric guitars and basses: remove. Electronics, pickups and pots should be checked if they were exposed to high humidity.
• Upright and grand pianos: usually too heavy to move. Close the lid and fallboard, cover completely, and arrange for a piano technician to inspect the action, hammers, felts and pedals.
• Drum kits: shells can often be wiped and dried. Real-skin drum heads with mold should be assessed and usually replaced. Remove cymbals and hardware for cleaning and drying.
• Wind instruments: remove. Clean and disinfect mouthpieces and bodies according to the manufacturer's guidance; pads on woodwinds may need replacement if they were soaked.
• Amplifiers, keyboards, mixers and PA systems: switch off, unplug and remove. Do not power on anything that was wet until an electrician or technician has checked it.
• Vintage or collectible instruments: always remove them and seek specialist advice. Do not expose them to any treatment until a specialist has assessed them.

With the instruments out of the way, the room itself can be treated far more effectively and with less risk.

It is also wise to photograph each instrument and note its condition before it leaves the room. A simple record of serial numbers, visible damage and where each item has been taken makes it much easier to coordinate with technicians, track repairs, discuss insurance or supplier warranties, and make sure nothing goes missing during a busy recovery week. For shops, the same record helps decide which stock can be sold as normal, which should be discounted after repair, and which should be written off. Taking an hour for this step at the start saves a great deal of confusion later, especially when several people are helping to move equipment at once.

The Solution: Controlled-Dose Ozone Treatment Combined with Disinfection Fogging from World Health Disinfection

World Health Disinfection (WHD) provides an ozone treatment service with the dose adjusted to room size and contents, reducing airborne mold spores and breaking down musty odor in rehearsal rooms, classrooms and shop floors. This is combined with a disinfection fogging service using Chemgene HLD4H on floors, walls, shelving, desks, chairs and high-touch surfaces, without fogging directly onto instruments.

Step-by-step process for music schools and instrument shops

1. Site survey and sequencing. The team inspects rehearsal rooms, classrooms, the shop floor and storage, identifies mold and humidity, and works with the owner to list the instruments that must be moved out.
2. Removing instruments from the room. Guitars, violins, wind instruments, real-skin drums and electronics go to a dry room for technician inspection. Pianos that cannot be moved are closed and fully covered.
3. Removing damaged materials. The team recommends pulling up submerged carpet and underlay and replacing lower acoustic panels that are damp or moldy, because these materials hold contaminated water inside.
4. Disinfection fogging with Chemgene HLD4H. ULV fogging covers floors, walls, the wall areas exposed behind removed acoustic panels, desks, chairs, music stands and door handles.
5. Controlled-dose ozone treatment. The room is sealed and treated at a dose suited to its size and to any items that remain. No people, pets or plants may be inside during treatment.
6. Ventilation. Doors and exhaust fans are opened for the time the team specifies, until the ozone has broken down into oxygen.
7. Re-check and humidity advice. Odor and mold are checked again, and the team advises on running dehumidifiers before instruments are brought back into the room.

Bringing instruments back in

Once the room has been treated and ventilated, resist the urge to carry everything back in the same afternoon. Run a dehumidifier for a few days and watch the humidity level settle. Bring instruments back gradually, starting with the most robust, and keep an eye on how they respond. Wooden instruments in particular appreciate stable conditions; a room that swings between very damp and very dry can cause as many problems as the flood itself.

Reassuring parents

Parents are the decision-makers for most music students, and they will want to know that the rooms are safe. A short message to the class LINE groups explaining what was done, including the removal of damaged carpet and panels, disinfection fogging, ozone treatment and ventilation, helps families feel comfortable bringing their children back. Offering a quick look at the rehearsal room before the first lesson can also go a long way toward restoring confidence.

A Rainy-Season Plan for Music Businesses

Once the school is running again, it is worth spending an afternoon on a simple plan for the next heavy rain. Bangkok's rainy season returns every year, and low-lying lanes in Huai Khwang and Din Daeng can flood again with little warning. A few decisions made now can save weeks of disruption later.

• Know what moves first. Make a short priority list: the most valuable instruments, the electronics, the student records and the sheet music library. Keep it on the wall by the stairs so any staff member can act quickly.
• Raise what cannot move. Piano risers, sturdy platforms for drum kits and wall-mounted shelving for amplifiers keep heavy items above typical flood levels.
• Choose flood-tolerant finishes. When replacing rehearsal room flooring, consider vinyl or tiles with rugs that can be lifted, instead of wall-to-wall carpet. Mount acoustic panels slightly off the wall and start them a little above floor level so they can dry and be inspected.
• Control humidity all year. A dehumidifier with a humidity display in each closed room protects instruments every day, not only after floods.
• Keep digital backups. Scan student records, lesson plans and important scores, and store copies off-site or in the cloud.
• Agree on a recovery contact. Save the WHD contact details along with your piano technician, luthier and electrician, so that the recovery can start the day the water goes down.

The cost of waiting is real. Every extra week of high humidity gives mold more time to spread into felts, case linings and unfinished wood, and every week of cancelled lessons risks losing students to another school. A clear plan turns the next flood from a crisis into an inconvenience.

10 Reasons Music Schools and Instrument Shops in Huai Khwang Choose WHD

1. Controlled-dose ozone treatment matched to room size and remaining items. See the ozone treatment service.
2. A plan to separate instruments before work starts, reducing risk to leather, rubber and felt.
3. An understanding of sealed rehearsal rooms, where moisture and odor hide behind panels and under carpet.
4. Disinfection of surfaces students touch with Chemgene HLD4H.
5. Odor removed at the source, not masked. Read more about ozone odor removal.
6. Care for students with allergies, with clear ventilation times before classrooms reopen.
7. Protection for electronics: amplifiers, mixers and keyboards are switched off, unplugged and moved or covered.
8. Scheduling on days without classes so student timetables are not disrupted.
9. Ongoing care advice, including humidity control and using Chemgene HLD4H spray on desks, chairs and music stands.
10. Easy to reach: call 065-556-6294 or LINE @whd268. Service covers Huai Khwang, Din Daeng, Rama 9 and all of Bangkok.

Before and After Ozone Treatment and Disinfection Fogging

Customer Voice (Example Scenario)

"I was really worried that ozone would harm the pianos and drums. On the survey day the team told us exactly what to carry out and what to cover, and they were straightforward that the carpet and lower acoustic panels needed replacing, while the instruments should go to a technician separately. Afterwards the rehearsal room no longer had that musty smell, the kids came back to class, and the parents who had been anxious felt much better."

- Teacher Phum, music school and instrument shop owner, Huai Khwang (example scenario)

Checklist for Instruments and Rehearsal Rooms After the Flood

• Move wooden instruments to a dry room with a dehumidifier. Do not sun-dry them or use hot air.
• Open fabric-lined cases to let air through, and replace cases that were submerged.
• Have a piano technician inspect the inside of each piano, including felts and pedal mechanisms.
• Have an electrician check amplifiers and keyboards that were exposed to water before switching them on.
• Keep humidity in the instrument storage room stable rather than letting it swing quickly.
• Clean mouthpieces and wind instruments according to the manufacturer's guidance before use.
• Check rehearsal rooms for odor and mold every week for the first one to two months.
• Store sheet music and method books on higher shelves or in sealed boxes in future rainy seasons.
• Wipe music stands, chairs, desks and door handles with disinfectant before the first lessons, and keep a spray bottle handy for daily use during the first weeks.
• Ask teachers to report any musty smell or sneezing among students, so problems can be spotted and addressed early.

Frequently Asked Questions

Q: Can a room be treated with ozone while a piano is still inside?
A: If the piano cannot be moved, the team will recommend closing the lid and covering it fully, and will keep the ozone dose low and appropriate. A piano technician should also inspect the interior after a flood.

Q: Will ozone remove mold from a guitar?
A: Moldy instruments should be cleaned directly by a technician. Ozone treatment focuses on the air and odor in the room, not on restoring individual instruments.

Q: Do all damp acoustic panels need replacing?
A: Panels that were submerged or show mold should be replaced. Upper panels that are dry and odor-free may be kept. The team will help assess this during the survey.

Q: When can students come back?
A: After ventilation for the full time the team specifies and once the room is dry. In most cases classes can resume the next day.

Q: Can a windowless rehearsal room be treated?
A: Yes. The team plans ventilation using exhaust fans and open doors and sets a safe re-entry time.

Q: Will an instrument shop with lots of stock need to close for long?
A: Most jobs are completed within one day, depending on the size of the shop and the amount of stock that needs to be moved.

Bring Music Back to Your Rehearsal Rooms, Safely

Book Ozone Treatment - Click Here

View Disinfection Service - Click Here

Call 065-556-6294 · LINE @whd268 · Email worldhealthdisinfection@gmail.com

Related Links

• Ozone odor and chemical residue removal
• Master Ozone Generator
• Dust mite removal service
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• External source: World Health Organization: Floods and health