A Story from the Field: Grandfather's Shop and the Smell That Reached the Bedroom

Wilaiwan, whom regular customers call "Jae Lin", is the third generation to run a dried-goods and tea shop in a four-storey shophouse down a narrow lane just off Yaowarat Road in Samphanthawong district. The ground floor is the shop her grandfather opened as a young man: old wooden cabinets, shelves stacked with shiitake mushrooms, dried shrimp and seaweed, and tins of tea lining every wall. The second floor holds the family living room and the shrine room. The third and fourth floors are bedrooms for Jae Lin, her husband, their teenage daughter and her seventy-eight-year-old grandmother.

During the Bangkok floods of October 2026, a high Chao Phraya River combined with heavy rain. Water came into the shop almost to knee height and stayed for three days. The family lifted what they could onto higher shelves, but the lower rows of stock, the cardboard boxes and the wooden cupboards under the counter all went under. When the water dropped, everyone shovelled out the mud, hosed the floor, threw away wet stock and left the folding steel shutter open all day to let the smell out.

A week later the shop was still closed. The musty, muddy smell was too strong. Regular customers walked past and asked when she would reopen. But what worried Jae Lin most was upstairs. Every night the damp smell crept up the wooden staircase to the third floor. Her grandmother had developed a lingering cough and complained that she could not sleep. Her daughter had an itchy rash on her arms. And on the shrine room wall on the second floor, small black spots of mold had started to appear, even though the water had never come close to that level.

This happens in many shophouses across Yaowarat, Sampeng, Talat Noi and Chakkrawat. This article explains why a flood that only reaches the ground floor can cause problems all the way to the top, and how to restore a shophouse systematically, one floor at a time. The good news is that, with the right order of work, both the shop and the home can recover fully.

Why a Ground-Floor Flood Sends Odor and Mold Upstairs

The staircase acts like a chimney. A shophouse has a central staircase that runs openly from the ground floor to the top. Warm, humid air from the flooded floor rises naturally, carrying moisture, musty odor and mold spores to the upper floors. This is worst at night, when every door and window is shut.

Shared walls with neighbours. Shophouses are built in long terraces, and the side walls are shared with the units next door. If a neighbour has not cleaned up yet, moisture and odor can seep through the party wall and through gaps under the roof.

Old buildings, absorbent materials. Many Yaowarat shophouses are decades old, with wooden stairs, timber upper floors, wooden ceilings and traditional lime or cement plaster. All of these hold moisture well, so mold can grow even in places the water never touched.

Little ventilation. Shophouses have windows only at the front and back. The middle of the building gets almost no airflow, so storerooms and the kitchen behind the shop are the stuffiest places in the building.

Rats and insects from old drains. In an old district with many restaurants and ageing drains, rats often move into buildings after a flood. Rat urine is how leptospirosis spreads, and cockroaches carry germs from the drains into the shop.

The kitchen and bathroom behind the shop. Most shophouses squeeze a small kitchen, a bathroom and a floor drain into the back of the ground floor. During a flood, these drains are often where dirty water first pushes up into the building, and after the flood they stay damp the longest. Grease, food scraps and sewage residue trapped in the drain, the U-bend and the gaps behind the sink can keep producing a sour, rotten smell for weeks. Unless the drains are flushed, the traps refilled with clean water and the area disinfected, this smell joins the musty odor rising up the stairs and can easily be mistaken for mold alone.

The Damage That Follows, for Both Shop and Home

• The family's health. Older relatives and children sleeping upstairs breathe mold spores every night and may develop allergy symptoms, coughing, sneezing, wheezing or skin rashes. Whoever works in the shop is exposed to floodwater residue, with a risk of diarrhea and infected cuts.
• Stock and food safety. Any dried food that touched floodwater must be thrown away, even if the packaging looks fine. Stock on high shelves that stayed dry can still absorb odor and humidity if it sits in a musty room for days, and may start to grow mold.
• Lost income. Every day the shop is closed is income gone, and regular customers may start buying from the shop down the lane.
• The shop's reputation. Customers notice a musty smell in a food shop the moment they step through the door, and social media reviews spread quickly.
• Things with sentimental value. Grandfather's old cabinets, the shop sign, family photos and the altar table in the shrine room can be lost to mold if it is left to spread.

Common Fixes That Do Not Finish the Job

Leaving the steel shutter open all day. It airs the front of the shop, but the breeze never reaches the middle and back of the building. At night, when the shutter comes down, the smell builds up again.

Pouring bleach over everything. The chlorine smell climbs the staircase to the bedrooms just like the musty smell does, it is not suitable for a shop selling food, and it does not reach mold inside timber.

Burning incense. It covers the odor briefly but adds smoke to a building that already has poor ventilation.

Cleaning only the ground floor. Many families scrub the shop spotless but ignore the staircase and upper floors where mold has already started. Spores from upstairs then drift back down into the shop.

Repainting straight away. Old plaster walls are still wet inside. New paint will blister and the mold will come back within a few months.

A Floor-by-Floor Recovery Plan

The key to restoring a shophouse is to work from the bottom up while thinking about the whole building at once. We recommend this order.

1. Have an electrician check the ground-floor wiring before switching on display fridges, shop lights or any socket that was under water.
2. Sort the stock. Throw away all food and goods that touched floodwater. Move stock that stayed dry to another place temporarily, in sealed containers.
3. Remove absorbent materials. Cardboard boxes, wooden pallets, swollen plywood cupboards under the counter and door mats.
4. Clear mud and dry the building. Use extraction fans to push air out through the front and back, and run dehumidifiers in storerooms.
5. Disinfect the whole shop, the kitchen behind it and the staircase.
6. Disinfect and ozone-treat the upper floors one by one, especially the shrine room, the elderly relative's bedroom and any room where mold spots have appeared.
7. Ventilate, re-check, then reopen, once the whole building is free of musty odor both in the morning when you open up and at night when the building is closed.

On the day of the ozone treatment, the family should leave the whole building, because the staircase connects every floor. Stay with relatives or at a nearby hotel for a day, and let the neighbours on either side know in advance.

The Solution: Shophouse Disinfection Fogging and Ozone Treatment by WHD

ULV disinfection fogging. Our team uses CHEMGENE HLD4H disinfectant as a fine mist that reaches behind wooden cabinets, under shelves, into the gaps around the staircase and into the stuffy corners behind the shop. It reduces bacteria, viruses and fungi on surfaces without leaving a strong chlorine smell that would drift up to the bedrooms. See our disinfection service for details.

Ozone treatment, floor by floor. After fogging, we run a professional ozone generator at a dose calculated for the volume of each floor. Because ozone is a gas, it reaches into timber, curtains, mattresses and the hollow spaces inside cabinets, helping to reduce mold spores and break down odor molecules. Read more about our ozone treatment service.

How We Work

1. Whole-building survey, from the shop and back kitchen up the staircase to the top floor, to find damp spots and the route the odor takes.
2. Advice on sorting stock and stripping out materials: what must go and what can be saved.
3. Preparation. Food stock, plants and pets are moved out; sensitive electronics such as cash registers and some CCTV units are covered or moved.
4. ULV fogging of the shop, staircase and upper floors.
5. Ozone shock. The building is closed. Nobody, no pets and no plants may be inside during treatment.
6. Ventilation. Front and back doors are opened until the ozone has broken down into oxygen.
7. Re-check of the whole building, with advice on controlling humidity.

Ozone Safety in a Shophouse

Ozone at treatment concentrations irritates the airways, so nobody can be in the building during treatment and the full ventilation time must pass before anyone returns. We control the ozone dose for each floor, cover or remove sensitive electronics, paintings, collectibles and rubber items, and recommend sealing any openings into neighbouring units during treatment so the ozone does not disturb the people next door. Food stock must not be in the building during fogging or ozone treatment, and surfaces that touch food directly should be wiped and rinsed as our team advises before stock goes back on the shelves.

Checklist Before You Reopen the Shop

• Close the building overnight and open it in the morning. If you can still smell mustiness, there is still a damp spot or an odor source somewhere.
• Shelves, counters and scoops used for weighing out goods have all been washed and disinfected.
• Display fridges and freezers have been checked by an electrician and have no lingering smell.
• No sign of rats, such as droppings or gnaw marks. If there are, deal with them before bringing stock back in.
• Stock is placed on raised shelving, and no boxes are pushed against walls that were wet.
• The upper floors are free of musty odor, and nobody in the family has a cough or rash that is getting worse.

Working with Your Neighbours

A shophouse terrace behaves a little like one long building. If your unit is clean but the unit next door is still full of wet stock and mud, some odor and humidity will keep finding its way through the shared wall, the roof space and the back lane. A few practical ideas help:

• Talk early. A quick chat with the neighbours on both sides about when each of you plans to clean and treat your units avoids surprises on treatment day.
• Coordinate where you can. When several units on the same terrace are treated within the same few days, the result usually lasts longer for everyone, because the musty air is not simply moving from one unit to the next.
• Clean the back lane together. Mud, rubbish and blocked drains in the narrow lane behind the shophouses are a common source of smell and rats. A joint clean-up of the lane makes a real difference.
• Agree on rat control. Rats travel along the whole terrace. Treating just one unit often only moves the problem along.

Good relations with neighbours also matter in a close-knit area like Yaowarat, where families have often run shops next to each other for generations.

Keeping the Building Dry in the Months Ahead

Old shophouses dry slowly. Even after a successful treatment, it helps to keep a simple routine for the next few months, especially through the rest of the rainy season.

• Open the front shutter and the back door together for at least an hour each morning, so air can actually flow through the building rather than just in at the front.
• Run a dehumidifier in the storeroom and the shrine room, and empty it daily.
• Keep a small gap between stock and walls, and store dry goods in sealed tubs rather than open sacks.
• Check the staircase and upper-floor walls every week with a torch, looking for new spots of mold, particularly behind furniture.
• Use a disinfectant spray such as CHEMGENE HLD4H 750 ml on counters, door handles and the staircase rail as part of daily cleaning.

Keep, Clean or Throw Away? A Quick Guide for a Dried-Goods Shop

Sorting stock and fittings after a flood is emotionally hard, especially when the shop has been in the family for generations. These simple rules make the decisions clearer.

• Throw away: any food, dried goods, tea, spices or herbs that touched floodwater, including items in paper, plastic bags, cardboard or loosely sealed tins. Also discard cardboard boxes, paper bags, labels and wrapping material that got wet, and sacks used for storing rice or beans.
• Usually throw away: plywood or particle-board cupboards that have swollen, fabric chair cushions, floor mats and anything soft that soaked up water for more than a day.
• Clean and disinfect: solid hardwood cabinets, metal shelving, glass jars with tight lids, stainless steel scoops, scales and counters. Wash off the mud, let them dry fully, then disinfect them before use.
• Check carefully: stock that was on high shelves and never touched the water. If the packaging is sealed and dry, with no mold and no unusual smell, it can usually be kept. If anything about it seems wrong, let it go.
• Ask a technician: display fridges, freezers, scales with electronics and cash registers that sat in water. Do not switch them on until they have been checked.

When the shop is a family heirloom, it can help to photograph old cabinets, signs and fittings before deciding. Solid wood often survives a flood better than people expect once it has been cleaned, dried slowly and treated for mold, while cheaper modern fittings rarely do. Our team can give an honest opinion on site, but the final decision is always yours.

10 Reasons Yaowarat Shophouse Owners Choose WHD

1. We treat the shophouse as one connected system, not just the shop front.
2. We plan the work floor by floor around your opening hours.
3. CHEMGENE HLD4H leaves no harsh smell in a food shop.
4. ULV fogging reaches behind wooden cabinets and around the staircase.
5. Ozone treatment deals with the musty odor that rises to the bedrooms.
6. Straightforward advice on which food stock to keep and which to throw away.
7. Careful handling of the shrine room and items of sentimental value.
8. Consideration for neighbours on both sides during ozone treatment.
9. Follow-up services such as dust mite removal for upstairs mattresses and mosquito spraying around the building.
10. Service across Yaowarat, Sampeng, Talat Noi, Chakkrawat and nearby areas.

Before and After Restoring the Whole Shophouse

A Shop Owner's Voice (Example Scenario)

"All I could think about was reopening, so I scrubbed downstairs three times. Upstairs just got worse. The team looked around and told me the staircase was how the smell was getting up, and that we had to treat the whole building. We spent one night at my sister's place, and when we came back the building didn't smell anymore. Grandma slept through the night, and the shop reopened that same week."

— Jae Lin, dried-goods and tea shop in a lane off Yaowarat Road (example scenario from field experience)

Frequently Asked Questions

Q: Only the ground floor flooded. Do we really need to treat upstairs?
A: If the upper floors smell musty or you can see mold spots, yes. The staircase carries moisture and spores upwards, and if only the ground floor is treated, spores from upstairs can drift back down.

Q: How long will the shop need to stay closed?
A: It depends on the damage and how wet the walls are. The fogging and ozone work itself usually takes a day, but the building needs to be dry enough first. We assess this during the survey.

Q: Can I still sell stock that was on high shelves and stayed dry?
A: If the packaging is sealed, dry, free of mold and has no strange smell, it can usually still be sold. Move it out during fogging and ozone treatment and inspect it carefully before putting it back on sale. If in doubt, throw it out.

Q: Will ozone leak into the shophouse next door?
A: We recommend sealing openings between units, control the ozone dose and suggest telling your neighbours in advance. If they were flooded too, treating several units at the same time works better.

Q: What about the shrine room and altar?
A: Buddha images and offerings made of metal or porcelain are usually fine. Fabrics, paper and old photographs can be covered or moved as appropriate, and we discuss this with the family before we start.

Q: Do you serve Yaowarat and nearby areas?
A: Yes: Samphanthawong, Pom Prap Sattru Phai, Phra Nakhon, Bang Rak and the rest of Bangkok. Contact us on LINE @whd268.

Reopen the Shop, Make the Home Comfortable Again

Book a whole-building survey of your shophouse in Yaowarat or Samphanthawong, from the shop floor to the top floor.

See Disinfection Service – Click Here

Book Ozone Treatment – Click Here

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

Related Links

• Residential ozone disinfection
• Ozone treatment for odors and chemical residue
• CHEMGENE HLD4H 750 ml spray for counters and shelving
• All articles

Health references: World Health Organization: Floods · Department of Disease Control, Thailand