A Story from the Field: Three Storeys, Three Generations

Wit is in his forties and lives in a three-storey shophouse down a narrow lane in the old Talat Noi community of Samphanthawong, Bangkok, together with his mother, who is in her seventies, and his daughter, who is in primary school. The building dates back to his grandfather's time. Its walls are brick with old plaster. The ground floor is the family's engine spare-parts shop, still open for business after decades. The second and third floors have timber floorboards, folding wooden shutters across the front, a steep and narrow wooden staircase, and, on the second floor, the family's shrine and ancestral altar.

During the October 2026 floods, the Chao Phraya ran high for days on end. Heavy rain on top of the high river pushed water back up through the lane's drains, and a mix of water and mud flowed into the ground floor until it reached almost to the knee. The family carried some of the stock upstairs in time, but the wooden shelving, an old glass display cabinet and the cardboard boxes under the counter sat underwater for four days.

When the water receded, Wit shovelled out the mud and washed the floor himself. A week later, though, a band of white salt crust had appeared on the ground-floor walls, higher than the water had ever reached. Paint was peeling off in sheets. Black mold spots had appeared in the corners. A musty smell, part dried mud and part sewage, simply would not go away. Strangest of all, the smell had drifted up to the second floor. A few floorboards had started to cup, and fluffy white mold had grown on the lowest steps of the wooden staircase.

His mother began coughing at night. His daughter complained of itchy arms. Customers who came in for parts remarked, "It smells strong in here." Wit wanted the problem sorted, but he hesitated. A builder who had looked at the house told him to paint waterproof coating over every wall and rip out the timber floor, and he did not want to do that to a house his family had lived in for three generations. His question was: "Is there a way to disinfect and get rid of the smell without destroying what makes our home what it is?"

Why Old Shophouses in Riverside Communities Recover More Slowly Than Modern Homes

• Old brick and plaster absorb water and release it slowly. Traditional brick and plaster are very porous. Water that soaks in on the day of the flood evaporates out over several weeks, and during that time the wall stays damp and becomes a home for mold.
• Moisture climbs above the flood line. Water inside the brickwork wicks upward. That is why salt crust and peeling paint appear higher than the floodwater actually reached.
• Walls are shared with the neighbours. A row of shophouses shares party walls from one end to the other. If the unit next door is still damp or has not been cleaned, moisture and smells pass through.
• Timber floors and staircases. Old timber picks up moisture rising from the ground floor and holds on to it. The space under floorboards and beneath the stairs is dark and still, ideal conditions for mold.
• Narrow lanes, little sunlight. Talat Noi's lanes are narrow and the buildings stand close together. Sun and breeze reach them far less than they reach a house in a suburban estate, so drying takes longer.
• Old drainage. The plumbing in older buildings may lack effective odour traps. When floodwater backs up, it leaves sediment and sewer smells in the pipes.

None of this means an old shophouse is a lost cause. It simply means the building needs to be treated on its own terms. Modern methods designed for concrete and gypsum board can work against a structure that was built to breathe.

The Risks Facing Families in Old Shophouses

Health, for every generation in the house

Floodwater that backs up from drains is often mixed with sewage and bacteria such as E. coli, which raise the risk of diarrhoeal illness and skin infections. Mud and standing water in old market districts, where rats are common, also carry a risk of leptospirosis. Meanwhile, mold spores from damp walls and timber floors can trigger coughing, sneezing, allergies and asthma, especially in older people and young children who spend most of the day at home. This is general information, not medical advice; anyone with fever, persistent cough or infected skin should see a doctor.

The shop on the ground floor

For a shophouse with a business downstairs, a musty smell is the first thing customers notice. Goods on display, such as cardboard boxes, labels and packaged products, can grow mold or simply look tired and unappealing. Small community shops depend on regulars and on visitors walking through, so the impression a shop gives really matters.

The value of the building itself

An old shophouse is more than a place to live. It holds a family's memories and contributes to the character of the whole neighbourhood. Fixes that involve ripping things out, or sealing everything under modern materials without understanding how the building works, can trap moisture inside the walls and create worse problems in the long run.

Common Fixes That Do Not Suit Old Buildings

• Painting waterproof coating over walls that are still damp. Old brick walls need to breathe. Sealing them while they are wet traps the moisture inside. The paint blisters and peels, and mold grows again underneath.
• Pressure-washing walls and timber floors. High-pressure water can blow old plaster off the wall and drive even more water into brick and between floorboards, which slows drying further.
• Pouring on strong bleach. Bleach can stain timber floors and wooden shutters and leaves fumes hanging in rooms with limited airflow, while doing little to mold that has grown deep into porous materials.
• Covering the smell with perfume or incense. The musty smell from the walls and drains is still there, just masked for a while. Burning things in a closed room to cover odours is not good for older family members either.
• Treating your own unit and ignoring next door. With shared walls, talking to the neighbours and working at the same time makes results last much longer.

The Solution: Low-Moisture Disinfection and Controlled Ozone Treatment by WHD

World Health Disinfection (WHD) offers a disinfection service and an ozone treatment service that suit old shophouses well. Neither needs large volumes of water, neither requires demolition, and both can be carried out in tight spaces.

ULV disinfection with CHEMGENE HLD4H

CHEMGENE HLD4H disinfectant is applied as an ultra-fine mist from an ultra-low-volume (ULV) fogger. The mist drifts into wall corners, under shelving, beneath the staircase, into the gaps between floorboards and around the drains. Because it uses far less liquid than washing down, it does not re-soak brick walls or timber floors. It deals with bacteria, viruses and mold on surfaces contaminated by floodwater.

Ozone treatment to reduce spores and break down musty odours

After disinfection, the team uses a Master Ozone Generator to treat the building one floor at a time. Ozone gas penetrates the spaces under the floorboards, behind cabinets and into porous materials. It helps reduce mold spores and breaks down the smell of mud, sewage and mustiness that rises from the ground floor.

Safety and care for old belongings

• No people, pets or plants may remain on the floor being treated during ozone treatment. Older relatives and children should stay somewhere else for the time being.
• After treatment, open the folding shutters and windows for the ventilation time the team specifies before anyone returns.
• Old photographs, important papers, silk, collectibles and electronics should be removed or covered. The team controls the ozone dose to suit the space.
• For the shrine room and ancestral altar, the family moves or covers sacred items themselves, according to the household's own beliefs and customs. The team works respectfully and does not touch any objects of worship.
• Old wiring that was underwater should be checked by an electrician before it is switched back on.

Restoring an Old Shophouse, Floor by Floor

1. Survey. Check the flood line, the salt band, mold spots, cupped floorboards and drains, and ask how the neighbouring units are doing.
2. Clear-out advice. Cardboard and materials that sat underwater for days should go. Swollen particleboard shelving is usually worth replacing. Solid timber shelving and old glass cabinets that are still sound can be wiped clean of mud and left to air-dry.
3. Bring the moisture down. Open the shutters, use fans to keep air moving and let the walls dry continuously. Avoid washing them again.
4. Disinfect the ground floor with CHEMGENE HLD4H: the floor, walls up past the stain line, under the counter, under the stairs and around the drains.
5. Disinfect upper-floor trouble spots, such as the underside of the floor near the stairs and damp wall corners.
6. Ozone treatment floor by floor, sealing each level and releasing ozone according to its size, with nobody inside that part of the building.
7. Ventilation. Open the shutters and windows on every floor until the ozone smell has faded.
8. Re-check and long-term advice. Follow up on odour and mold, and wait until the walls are fully dry before repairing finishes with breathable materials.

Bring the Neighbours In: The Strength of a Shophouse Row

A row of shophouses behaves like one long building divided into rooms. The units share walls, share drains and share the same lane. If one unit is disinfected and ozone-treated while the one next door still has mud in the corners and a musty smell, the problem can find its way back.

So Wit talked to the two neighbouring households, who were dealing with much the same thing. Booking all three units on the same day let the team plan a single trip down the narrow lane with its equipment, and every unit was brought to the same standard. It also meant the shops along the lane could reopen together, so regular customers and visitors walking through could see that the community was back on its feet.

If you are organising your own lane, a simple list helps: which units flooded, roughly how high the water reached, whether each ground floor is a shop or living space, and who in each household is elderly, very young or has breathing problems. With that information, the team can suggest a sensible order of work for the whole row.

There is a social benefit too. Recovery after a flood can feel lonely, especially for older residents who have watched the lane change over decades. Working through it as a row, comparing notes on what dried well and what did not, and reopening the shops together turns a stressful clean-up into something the community does side by side.

Living with an Old Building After the Flood: Habits That Help

• Keep air moving. Open the shutters on dry days and run a fan near damp walls. Moving air is one of the best allies an old brick wall has.
• Brush, do not scrub. Salt crust can be brushed off with a dry brush and swept away. Scrubbing with water only feeds the wall more moisture.
• Raise stock and furniture off the floor. A few centimetres of clearance under shelves and cabinets lets air reach the floor and the base of the wall.
• Keep drains topped up. Pour water into floor drains regularly so traps stay sealed, and clear the lane drains together with neighbours.
• Watch the stairs. The underside of the staircase is easy to forget. Check it for white or green fuzz every week or two during the rainy season.
• Be patient with repairs. Replastering or repainting too soon is one of the most common reasons mold returns in old buildings.

The First Week After the Water Drops: A Practical Order for Shophouse Families

Families often ask what they should be doing in the days before a professional team arrives. The order below is the one Wit followed, and it works for most old shophouses in the area.

Days one and two: safety and mud

Before anything else, keep the power off on the ground floor until an electrician has checked the wiring and the sockets that were underwater. Wear rubber boots and gloves when shovelling mud, and keep children away from the ground floor while it is being cleared. Floodwater mud from drains is not ordinary dirt. Bag it and set it out for collection rather than washing it down the lane drain, which only blocks the drainage for everyone.

Days two to four: sort and decide

Separate everything that was underwater into three groups: things that must go (soaked cardboard, upholstered items, food, anything soft that smells), things that can be cleaned and dried (solid timber, metal parts, glass, ceramics), and things that need a specialist (old photographs, documents, family heirlooms). Photograph the damage as you go. Those photos are useful later for insurance claims, for local government relief, or simply for your own records.

Days three to seven: dry and observe

Open the shutters every day the weather allows and run fans across the ground floor. Watch how the salt line and damp patches change. If the band of damp is still rising after a week, the wall is releasing a lot of water and needs more time. Notice where the smell is strongest: near a drain, under the stairs, behind a cabinet. Telling the team about these spots during the survey saves time and makes the treatment more precise.

A note on rats, insects and the lane

Old market districts have long had a rat population, and floods push rats into buildings looking for dry ground. Look for droppings along the walls and on shelves. Clean them wearing gloves and a mask, never by dry sweeping, because dust from droppings and urine can carry disease. Seal gaps under doors and around pipes where possible. Standing water left in buckets, plant pots and old tyres in the lane will breed mosquitoes within days, so empty anything that holds water. Working on this together with neighbours makes a much bigger difference than any one household acting alone.

10 Reasons Old Riverside Shophouses Choose WHD

1. No demolition needed: the disinfection service works with the building as it is.
2. Low moisture: ULV mist does not re-soak brick walls or timber floors.
3. A quality disinfectant: CHEMGENE HLD4H, used for high-level disinfection.
4. Stops odours drifting between floors with the ozone treatment service, one level at a time.
5. Fits narrow lanes: portable equipment suited to old communities.
6. Respect for heirlooms and sacred items: the family handles objects of worship, and valuables are covered.
7. Helps the ground-floor shop reopen by removing the smell customers notice first.
8. Can be planned with neighbours so several units are done on one day.
9. Mindful of elders and children, with clear safety guidance for residential ozone disinfection.
10. Extra protection: mosquitoes multiply after floods, and the mosquito spraying service can be added.

Before and After: Wit's Shophouse

In the Customer's Words

"Three generations have lived in this house, so I didn't want to tear anything out unless I had to. The team explained that old walls need to dry first and used a method that doesn't soak them again. We took care of the shrine room ourselves, and they respected that. The smell in the shop has mostly gone, and my mother is sleeping better."

— Wit, shophouse owner and spare-parts shopkeeper, Talat Noi, Samphanthawong (illustrative scenario)

Frequently Asked Questions

Q: My old brick walls have white salt crust. Should I scrub it off?
A: The crust comes from moisture evaporating out of the wall. You can brush it off with a dry brush, but avoid washing it with water. Let the wall keep drying, and disinfect any areas with mold.

Q: The second-floor boards have cupped. Do they need to come out?
A: Many solid timber boards flatten again as they dry. Wait, then have a carpenter assess them. Disinfection and ozone treatment deal with mold and odour beneath the floor without removing it.

Q: Can you ozone-treat the shrine room?
A: The family should move or cover sacred items themselves, according to their own beliefs. The team does not handle objects of worship and will advise on preparing the space before starting.

Q: How long do elderly relatives need to be out of the house?
A: They need to be off the floor being treated during ozone treatment and ventilation. The team gives clear timings. Some families treat one floor at a time so older relatives can rest on another level.

Q: Our lane is too narrow for a vehicle. Can you still come?
A: Yes. The equipment can be carried in. The team will ask about access beforehand to plan the visit.

Q: When should we repaint?
A: Only once the walls are completely dry, and preferably with breathable materials. Talk to a builder experienced with old buildings.

Make Your Family Shophouse a Healthy Home Again, Without Tearing Out the Memories

Shophouses and shops in Talat Noi, Samphanthawong, Yaowarat, Bang Rak and nearby riverside communities are welcome to contact us for advice.

See Disinfection Service, Click Here

Book Ozone Treatment, Click Here

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

Related Pages and Sources

• Residential ozone disinfection
• Ozone deodorising and chemical residue removal
• Mosquito spraying service
• All articles
• External sources: WHO: Floods and health and Department of Disease Control, Thailand

#PostFloodDisinfection #DisinfectionService #OzoneTreatment #MoldRemoval #MustySmellRemoval #Disinfectant #OldShophouseRestoration

Keywords: old shophouse mold after flood, heritage shophouse flood damage, damp brick walls, timber floor mold, musty smell removal, post-flood disinfection, ozone treatment, Talat Noi, Samphanthawong, Bangkok 2026