A Story from the Field: Wichai's Two-and-a-Half-Storey Townhouse

Wichai is thirty-eight and works as a production line supervisor at a factory in Khlong Luang, Pathum Thani. He lives in a two-and-a-half-storey townhouse with his wife and their four-year-old daughter. The house is just over four metres wide. The ground floor is a living room with a kitchen extension built onto the back, a small bathroom tucked under the stairs, and a front car port that doubles as the place where the family dries its laundry.

When the big flood arrived in early October 2026, water poured into the soi and rose almost a metre inside the ground floor. The family managed to carry some things upstairs, but the refrigerator, the kitchen cabinet, the sofa and the shoe rack spent nearly two weeks underwater. When the water finally drained away, Wichai walked back in alongside every other neighbour in the row. Every house had the same problem: a heavy, musty smell rising from the ground floor all the way up to the bedrooms.

The trouble with a townhouse is that it is narrow and has windows only at the front and the back. Air simply does not circulate well. Both side walls are shared with the neighbours, so moisture stays trapped in the masonry much longer than it would in a detached house. A week after the water receded, the living room wall started to show clusters of black spots. The kitchen extension at the back, with its metal-sheet roof, smelled constantly of drains. Their daughter developed an itchy rash on her legs after sitting on the floor to play, and his wife complained that she woke up congested every morning.

Wichai tried scrubbing the walls with bleach. The black spots faded for two or three days and then came straight back. That was when he started looking for information and contacted World Health Disinfection (WHD) for advice.

Why Townhouses and Row Houses Are Harder to Recover After a Flood

Townhouses and row houses are the most popular homes for working families in Khlong Luang, close to the industrial estates, universities and big wholesale markets. But when the ground floor floods, this type of building has specific weak points that make germs, mold and musty odors worse than in other homes.

• Poor cross-ventilation. With windows only at the front and the back, humidity lingers in the rooms and inside the walls for a long time. That is exactly the environment mold loves.
• Shared walls along the whole row. Moisture can travel from one house to the next, and if a neighbour has not cleaned up yet, mold can spread across the party wall into your home.
• Kitchen extensions at the back. These are often built at a lower level than the main house, with small drainage pipes that back up easily. They are usually where the smell is worst.
• The staircase acts like a chimney. Odors and mold spores from the ground floor drift up the stairwell into the bedrooms, so everyone in the house is affected even if they sleep upstairs.
• The bathroom under the stairs. It has no window, water sits there longest, and it is the entry point for sewage backflow from the drains.

The health impact on the family

Floodwater carries many kinds of germs into the house. Leptospirosis, spread through rat urine, enters the body through cuts and broken skin and begins with high fever, headache and calf pain. E. coli and other bacteria from sewage cause diarrhea. Prolonged contact with dirty water and mud causes skin inflammation and wound infections. Meanwhile, mold spores in the air trigger allergies, coughing, sneezing, congestion and asthma attacks. Small children who sit, crawl and play on the ground floor are the group to watch most closely, just as Wichai discovered with his daughter.

The impact on money and time

Many townhouse owners are still paying off a mortgage, so the last thing they want is to pay for the same repair twice. Yet if you repaint a wall that is still damp and full of mold, the paint will bubble within weeks. Particle-board furniture that you decided to keep may go moldy and need to be thrown away after all. And family members end up taking day after day off work to clean the same rooms again and again.

Why Scrubbing It Yourself Does Not Finish the Job

• Scrubbing walls with bleach. This lightens the black spots on the surface, but the mold threads rooted inside the plaster survive. In a narrow, enclosed space like a townhouse, chlorine fumes also sting the nose and irritate the eyes very quickly.
• One fan in the middle of the room. It helps some spots dry faster, but it does not kill anything, and it does nothing for dead-air pockets like the space under the stairs or behind the cabinets.
• Odor blocks and scented sprays. They only cover up the smell for a while. The source of the odor stays soaked into the walls, floors and drains.
• Painting with anti-mold paint straight away. Anti-mold paint is useful for prevention, but if it goes onto a wall that is still very wet and still contaminated, the result will not last.

A narrow home that has been underwater needs a method that reaches both the surfaces and the air across the entire ground floor, including the stairwell that connects to the floors above.

The Solution: Disinfection Fogging + Ozone Treatment Designed for Townhouses

WHD uses two complementary stages to deal with germs on surfaces, mold in the air and odors trapped inside materials.

Stage 1: Disinfection fogging with Chemgene HLD4H

Our disinfection service uses CHEMGENE HLD4H, delivered by ULV equipment as an ultra-fine mist. The droplets float into wall crevices, under the stairs, behind the refrigerator, beneath the sink and along door frames that sat in water. The disinfectant does not have the harsh, choking smell of chlorine, which makes it much more comfortable in narrow enclosed spaces, and it is not corrosive to normal household surfaces.

Stage 2: Ozone treatment for the ground floor and stairwell

Our ozone treatment service uses high-output ozone generators. Ozone is a gas with strong oxidizing power, and it penetrates every part of a narrow house very effectively. It helps destroy mold spores and microorganisms in the air, in curtains, sofas and rugs, and it breaks down the molecules responsible for musty and drain odors. After treatment, ozone decays back into oxygen. For a townhouse, our team positions the machines to cover the living room, the kitchen extension, the bathroom under the stairs and the stairwell itself.

Our service process for townhouses

1. Site survey. We check how high the water rose, the direction of airflow, damp pockets, the kitchen extension, the bathroom and the condition of the party walls you share with your neighbours.
2. Preparation advice. We explain how to remove mud and stains, clear out badly damaged items, store food and kitchenware, and move valuables and important documents upstairs.
3. Ground-floor fogging. We fog the living room, kitchen, bathroom, car port, lower stairs and the drainage channel in front of the house.
4. Ozone treatment. Doors and windows are closed, fans and air conditioners switched off, and the treatment runs for a time calculated from room volume and odor strength.
5. Ventilation. We open the front and back doors so air can flow straight through, use fans to push the air out, and only let the family back in once it is safe.
6. Re-check and aftercare. We check the odor again and advise you on reducing humidity in a narrow home: opening up during the day, using a dehumidifier and watching for any mold spots that try to come back.

10 Reasons Khlong Luang Townhouse Owners Choose WHD

1. Planned for narrow homes. Machines are positioned according to the townhouse layout, so the space under the stairs and the back kitchen are never missed.
2. Fine mist reaches every corner. ULV disinfection fogging gets to places a cloth never will.
3. No chlorine fumes in a closed space. Chemgene HLD4H is far more comfortable to use in small homes.
4. Odors that rise upstairs are dealt with. Ozone treatment covers the stairwell too.
5. Fewer allergy-triggering spores. Especially important in homes with small children.
6. Walls ready for repainting. Lower risk of paying for the same repair twice.
7. Fast turnaround. A typical townhouse can usually be completed in a single day, depending on site conditions.
8. Whole-row bookings. When several neighbours book together, it helps stop mold travelling from house to house.
9. Post-flood extras. Mosquito spraying around the house and soi, since standing water brings more mosquitoes.
10. Easy to maintain yourself. Use the Chemgene spray on high-touch surfaces in daily life.

Before and After: Wichai's Townhouse Ground Floor

What Our Customer Said

"Our house is narrow and hardly gets any breeze. No matter how much we scrubbed, the smell would not go. The team explained that the ozone had to reach the stairwell as well, because the smell was rising upstairs. When we came back in afterwards, the house felt so much lighter. Now several neighbours in our soi have asked me for the number."
— Wichai (name changed), townhouse owner, Khlong Luang, Pathum Thani

Checklist for Townhouse Owners After the Water Recedes

• Cut the power to the ground floor and have an electrician check sockets, switches and the breaker before using them.
• Wear boots, gloves and a mask every time you clean, especially when shovelling mud out of the back kitchen.
• Lift the drain covers or inspection pits in front of the house to check for mud blockages, because blocked drains push sewage back inside.
• Take swollen plywood doors and cabinet doors outside to dry in the sun, and consider replacing any that have warped badly.
• Lift doormats, curtains and cushions and wash or dry them thoroughly.
• Talk to your neighbours about cleaning at the same time, to reduce moisture moving through the shared walls.
• Watch for fever, headache, calf pain, diarrhea or itchy rashes, and see a doctor promptly if they appear.

High-Risk Spots Our Team Pays Special Attention To

• The party wall shared with the neighbour. This is the slowest wall to dry because it can pick up moisture from both sides, so it is usually where mold appears first.
• Under the stairs and the bathroom. No windows and completely still air. We fog the walls, ceiling and floor thoroughly before positioning the ozone generator to cover them.
• The back kitchen extension. It holds grease, food scraps and wastewater from the drains. The main grime must be washed off first, then the sink, counters and floor are fogged again.
• Door edges and wooden frames. Timber soaks up water and keeps the moisture inside. If you see black marks or heavy swelling, plan to replace them later.
• The front car port and drainage channel. Mud left in the channel is a source of germs and mosquitoes, so it should be dug out and disinfected as well.

Knowing these risk points helps owners prepare their homes correctly and lets the fogging and ozone treatment work to their full potential. It also explains why townhouse recovery should never be treated as a smaller version of a detached-house job: the layout changes where moisture hides, where smells collect and how the air needs to be moved afterwards.

A Whole-Row Approach: Why Neighbours Should Recover Together

One thing that makes townhouse estates in Khlong Luang different from other neighbourhoods is how closely every home is connected. Party walls, shared roof lines, a common drainage channel along the front of the row and back gardens that sit side by side all mean that the condition of one house affects the next. If one owner treats their ground floor thoroughly while the house next door is left damp and full of mud for another month, moisture and mold can creep back through the shared wall. Smells from a neighbour's blocked drain can also travel along the same pipe network.

For this reason, our team often suggests that neighbours coordinate. When two, three or more houses in the same row are surveyed and treated over the same few days, the whole block dries out together, the drainage channel can be cleared and disinfected in one go, and mosquito breeding spots along the soi can be dealt with at the same time. Coordinating also makes it easier to manage ozone safety, because everyone in the adjoining homes knows when treatment is taking place and when it is safe to come back.

Even if your neighbours are not ready yet, it is still worth treating your own home early. Just let our team know about the situation next door during the survey, and we will advise you on extra precautions for the shared walls.

Why Timing Matters in the Weeks After the Water Recedes

October and November in Pathum Thani are still humid, and there can still be heavy rain as the season turns. That combination of warm air, high humidity and wet walls is ideal for mold. The first one to two weeks after the water drains away are when mold colonies establish themselves most quickly, and once they spread deep into plaster, timber and fabric, they take far more effort to remove.

Treating early has several practical benefits. Furniture and fabrics that are only lightly affected are more likely to be saved. The musty smell has less time to soak into curtains and sofas. Walls can start drying properly with the germ load already reduced, and you can plan repainting with confidence instead of guessing. Most importantly, the family spends less time living with airborne spores and floodwater germs, which is what really matters for young children and anyone with allergies or asthma.

A simple rule of thumb for townhouse owners: once you can walk across the ground floor without stepping in mud, it is time to call. You do not need to have finished every repair, replaced the furniture or sorted out the insurance claim. Those jobs can continue in parallel. What should not wait is dealing with the germs, spores and odors that are building up in the walls and the air every single day the house stays damp. Booking early also helps you secure a slot, because demand across Pathum Thani rises sharply as more families return home at the same time.

Frequently Asked Questions

Q1: Is it better to hire a cleaner first or call WHD first?
A: You can do either. Many families start the mud clean-up themselves or with a cleaning crew, then call us for disinfection and ozone. If you are unsure, call us first and we will tell you how much cleaning needs to be done before we arrive.

Q2: Only the ground floor of my townhouse flooded. Do the upper floors need ozone treatment too?
A: In most cases we focus on the ground floor and the stairwell. If the smell has reached the bedrooms upstairs, our team will assess it and advise whether extra treatment is worthwhile.

Q3: Will ozone treatment in my townhouse affect the houses next door?
A: We close any visible connecting openings and recommend that you let your neighbours know in advance. The treatment time is controlled, and the space is properly ventilated once the job is finished.

Q4: Do I need to wait until the walls are completely dry before calling you?
A: No. It is best to book once the mud and main stains have been removed, because treating early reduces the spread of mold. Then let the walls dry fully before repainting.

Q5: The back kitchen has a strong drain smell. Can the service help?
A: Fogging and ozone treatment reduce germs and odors in the space, but if the cause is a blocked pipe or inspection pit, the drain should be cleared at the same time. Our team will point out the problem spots during the survey.

Q6: We have a small child. When can we move back in?
A: You can return once ventilation has been completed for the time our team specifies, by which point the ozone has turned back into oxygen. We recommend keeping the windows open for a while longer afterwards.

Q7: Which parts of Khlong Luang do you cover?
A: We cover Khlong 1 to Khlong 7, the Rangsit area, Nava Nakorn and nearby areas of Pathum Thani. Contact us by phone or LINE to check availability.

Let Your Townhouse Ground Floor Breathe Again

Talk to the WHD team for a free consultation. We will assess your home and plan disinfection and ozone treatment to suit it.

Book Ozone Treatment – Click Here

See Our Disinfection Service – Click Here

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

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• All articles

External sources: World Health Organization – Floods and Department of Health, Ministry of Public Health, Thailand