A Story from the Field: A House Nobody Has Slept In That Smells Like It Was Abandoned

Mintra and her husband spent almost three years saving for the down payment on a two-storey townhome in a new housing estate in Bang Sao Thong. The ownership transfer was booked for the end of October 2026. They had already bought curtains, ordered a small bed, and planned for their three-year-old son to have a room of his own for the very first time.

Then the rain came, day after day. Water from the canals and the low-lying land around the estate spilled onto the internal roads. The house they had reserved was locked. Nobody lived there, nobody opened a window, and floodwater sat inside the ground floor at roughly twenty centimetres for several days.

When the water finally receded, the sales office called to say the developer would clean the house. Mintra asked to see it for herself. The moment the staff member unlocked the front door, a wave of damp, musty air mixed with the smell of river mud rolled out. A thin film of silt still covered the floor tiles. The gypsum wall under the staircase had a sharp, straight tide line. The particleboard cabinet under the kitchen sink had swollen at the base, and in one corner of the living room a scatter of small grey-green dots had begun to appear.

"Nobody has spent a single night in this house," Mintra said to her husband. "Why does it smell like a place that has been shut up for a year?" She was worried about their son, who already reacts badly to dust. And she did not know whether they should sign for the house on the original date, what repairs they should ask the developer for, or whether the basic clean the developer was offering would actually be enough.

Mintra is far from the only buyer in this position. During the 2026 floods, many new homes across Samut Prakan were sitting between completion and handover: finished, fitted out, and completely empty. This article brings together what buyers need to know, from inspecting the house and talking to the developer to restoring the home to a clean, safe condition before moving day.

Why a Locked, Empty New House Suffers More Moisture Damage Than You Expect

It is natural to assume that a new house with no furniture and no belongings will be easy to recover. In practice, an empty, sealed house has several weaknesses of its own, and they all work in favour of mold and odour.

• There is no ventilation at all. In an occupied home, people open doors and windows, run fans and switch on the air conditioning. A house waiting for handover stays locked. The moisture from standing water is trapped inside for days or weeks, and the relative humidity climbs well into the range where mold thrives.
• New materials absorb water readily. Gypsum board walls, ceiling panels, skirting boards and built-in cabinets made of particleboard or MDF all soak up water and hold it for a long time. Fresh plaster and recently applied paint may not have fully cured, which makes them even more vulnerable.
• Nobody sees the problem early. Mold usually starts growing within 24 to 48 hours of a material getting wet. If nobody is there to wipe surfaces or open the house, the growth spreads silently until someone finally comes to look.
• The plumbing has never really been used. Drains, inspection chambers and the septic tank may have taken in mud and dirty water that flowed backwards during the flood. Drain odours often appear only later, once the household starts using the bathrooms and kitchen every day.
• Small gaps become hidden reservoirs. The cavity behind a gypsum wall, the void under a built-in wardrobe, and the space beneath a staircase cupboard are all places where water can sit unseen and evaporate slowly into the rest of the house.

Health Risks Every Buyer Should Understand

Floodwater that has flowed across roads, through canals and back up from storm drains can carry bacteria such as E. coli, organisms that cause stomach and intestinal illness, and the bacteria responsible for leptospirosis. The residue left on floors and walls after the water recedes is therefore not just dirt. It can be a reservoir of germs, especially in corners and joints that a quick mop does not reach.

Mold growing on walls and cabinets releases spores into the air. For many people, breathing these spores can trigger allergies, asthma, a persistent cough, or irritation of the eyes, nose and throat. Young children, older adults and anyone with an existing respiratory condition are generally the most sensitive. For a family planning to move a toddler into a freshly decorated bedroom, that is a very real concern.

Financial and Time Risks

Most buyers of new homes are taking on a long mortgage. If they sign for the house and only afterwards discover mold behind the walls, cabinets that keep swelling, or a musty smell that will not go away, the repair bill lands on them at exactly the moment when their savings are stretched thinnest. A delayed move also means paying rent for longer, taking more days off work to visit the site, and carrying the stress of an uncertain moving date for the whole family.

There is also the question of evidence. Once a buyer has accepted the house, it can be harder to show which problems came from the flood before handover and which appeared afterwards. That is why the weeks before transfer are such an important window.

Before You Sign: How to Work with the Developer

Until ownership is transferred, the house generally remains in the developer's care. This gives buyers a valuable opportunity to inspect the property and ask for issues to be fixed before they accept it. The points below are general guidance only. Rights and responsibilities depend on the specific sale and purchase agreement for each project, so if you are unsure, ask the developer's legal or contracts team, or consult your own legal adviser.

1. Notify the developer in writing. Send a message or email to the sales office or customer service team. State your house number and plot number, explain that the house was flooded, and request a joint inspection once the water has gone. Keep a record of every exchange.
2. Take detailed photos and videos. Record the water line on walls, the cabinet under the sink, wooden doors and frames, skirting boards, low-level power sockets and every patch of mold you can find. Make sure each file is clearly dated.
3. Ask for a written list of remedial work. This might include replacing the lower section of gypsum walls that absorbed water, replacing swollen cabinets or door leaves, having a qualified electrician check the electrical system, and inspecting the water pump, septic tank and inspection chambers.
4. Ask how the house will be cleaned. Washing the floors and wiping the walls is a good first step, but it is reasonable to ask whether the developer also plans to disinfect surfaces and deal with mold spores in the air and in hidden corners.
5. Talk about timing. If repairs are still under way or the walls are still damp, discuss with the developer whether the transfer timetable allows the house to be inspected in a genuinely ready condition.

World Health Disinfection (WHD) can work directly with the project team. Sometimes the developer books the service before handover. Sometimes the buyer arranges it, either after transfer or beforehand with the developer's permission to access the site. Either way, our team schedules the visit through whichever channel all parties have agreed on, so the buyer is not left chasing every detail alone.

Why the Usual Quick Fixes Rarely Solve the Problem

• Scrubbing with bleach alone. Household bleach can lighten stains on smooth, hard surfaces, but it does not penetrate gypsum or wood that has soaked up water, and it does nothing about spores floating in the air. In a closed house, strong chlorine fumes can also irritate the lungs. Bleach must never be mixed with toilet cleaners or ammonia-based products.
• Running fans for a few days, then locking up again. Fans dry the surface, but the moisture inside the walls and cabinets remains. As soon as the house is sealed again, humidity rises and mold growth resumes.
• Painting over the stains. This is the one buyers should watch for most carefully. Mold that is painted over disappears from view for a while, but it is still alive underneath. Within weeks or months it can push the paint into blisters or produce fresh black spots.
• Air fresheners and scented sachets. These can mask the smell on inspection day, but they do nothing to the source of the odour.

A small tip for inspection day: if a house smells unusually strongly of perfume, or if some patches of wall have fresh paint that does not quite match the rest, ask the developer directly how that area was treated and request photos taken before the work was done. A reputable project will usually be happy to explain.

The Solution: Chemgene HLD4H Disinfection Fogging Plus Ozone Shock Treatment Before Move-In

Once the mud has been cleared, damaged materials have been removed and replaced, and an electrician has checked the wiring, the next job is to deal with what you cannot see: germs on surfaces and mold spores in the air. That is exactly what the WHD disinfection service and ozone treatment service are designed to do.

Ultra-Low-Volume (ULV) Disinfection Fogging

Our team uses CHEMGENE HLD4H disinfectant delivered through a fogger that produces very fine droplets. The mist drifts into corners, under the stairs, behind built-in cabinets and onto surfaces that a cloth simply cannot reach, helping to reduce bacteria, viruses and fungi left behind by floodwater. An empty house is actually ideal for this work, because the team can cover every room fully without working around furniture.

Ozone Shock Treatment

After fogging, the team sets up a high-output ozone generator, such as the Master Ozone Generator, inside the sealed house. Ozone gas spreads through every room, helping to destroy mold spores in the air and break down the molecules responsible for musty, muddy and drain-like smells. The duration and concentration are set according to the size of the house and the severity of the problem.

How the WHD Team Works, Step by Step

1. Survey and assessment. We look at the water line, mold spots and saturated materials, and discuss with the buyer or project staff what repairs are planned and when.
2. Preparation advice. All mud should be removed first. Swollen or deeply moldy materials should be taken out, and an electrician should check sockets and breakers before power is switched back on.
3. Disinfection fogging with Chemgene HLD4H. Every room is covered, including bathrooms, the space under the stairs, storage cupboards and the carport.
4. Ozone shock treatment. The house is closed during treatment, with no people, pets or plants inside.
5. Ventilation. Doors and windows are opened so the ozone can break down back into oxygen before anyone goes back in.
6. Re-check. We assess the smell and any remaining areas of concern, and give advice on controlling humidity once the family moves in.

10 Reasons New-Home Buyers Should Disinfect and Ozone-Treat After a Flood, Before Moving In

1. An empty house is the perfect moment. With nothing in the way, the team can reach every corner, and one visit covers the whole home.
2. It reduces flood-borne germs. Disinfection fogging helps cut bacteria carried in with the mud on floors and walls.
3. It reduces airborne mold spores. Ozone treatment reaches the air in every room, not only the spots you can see.
4. It tackles odour at the source. Ozone breaks down odour molecules instead of covering them with fragrance.
5. It protects the most vulnerable family members. Toddlers, older relatives and people with allergies move into a home with cleaner air.
6. It makes the final inspection clearer. Once smell and surface mold are dealt with, it is easier to spot any defects that genuinely remain.
7. It uses a purpose-made disinfectant. CHEMGENE HLD4H is the disinfectant our team uses for fogging work.
8. It lowers the chance of mold returning. Combined with removing damaged materials and controlling humidity, the problem is less likely to come back.
9. It can be coordinated with the developer. Our team schedules directly with the project office or the estate's juristic person, so buyers are not left coordinating every detail themselves.
10. You start life in your new home with peace of mind. No moving in while wondering whether mold is hiding in your child's bedroom. Learn more about residential ozone disinfection.

Inspection-Day Checklist for a Flooded New House

On top of the usual new-home snagging list, a house that has been flooded deserves some extra checks. Take your time on the day; a good inspection usually takes longer than people expect.

• Lower gypsum walls and skirting boards: press gently to see whether they are still soft or blistered, and look for mold spots or repeat water marks.
• Under-sink and built-in cabinets: check whether panels have swollen, edges have lifted, or a musty smell escapes when you open the doors.
• Door frames and wooden doors: do they open and close smoothly, or do they stick because the timber has swollen?
• Low-level sockets and switches: these should be inspected and signed off by the developer's qualified electrician.
• Water system: run every tap, flush every toilet, watch how quickly water drains, and sniff around floor drains and sink outlets for sewer smells.
• Septic tank and inspection chambers: ask whether the developer has inspected them and pumped out any silt.
• Water pump and storage tank: check that the pump works normally and that the tank was not contaminated by floodwater.
• Overall smell: close the house for a while, then walk back in. If there is still a clear musty smell, there is still moisture or mold that needs attention.
• Ceilings near the ground floor: on two-storey homes, look at the underside of the stairs and any ceiling void access point for staining or condensation.

Write everything down, photograph each point, and share the list with the developer the same day. A clear, shared record makes the next steps much easier for everyone.

After You Move In: Keeping Humidity Under Control

Even after a thorough clean, a home that has been through a flood benefits from some extra care during its first few months of occupation. Mold needs moisture, so controlling humidity is the best long-term defence.

• Open windows on both sides of the house for cross-ventilation on dry days, especially in the morning.
• Run bathroom and kitchen exhaust fans during and after showers and cooking.
• Leave cabinet doors slightly open for the first few weeks so air can circulate behind them.
• Avoid pushing beds and wardrobes tight against walls that were wet; leave a small gap for airflow.
• Have the indoor air-conditioning units cleaned before you start using them every night.
• Check the lower walls and cabinet bases every couple of weeks for new spots or a returning smell, and act early if anything appears.

If you notice the musty smell creeping back, a follow-up ozone treatment is usually far simpler than waiting for the problem to grow. For bedding and soft furnishings that came from your previous home, our dust mite removal service can also help.

A Buyer's Perspective

"At first we thought washing the floor would be enough. After talking it through with the developer, we asked them to remove the lower sections of wall that had soaked up water, and then we booked disinfection and ozone treatment before the final inspection. The house no longer smells the way it did on that first day. When we moved in, we felt much more at ease, especially about our son's room."
— Mintra (name changed), townhome buyer in Bang Sao Thong

This is an illustrative scenario based on situations commonly seen after floods. Actual results depend on the condition of each house.

Frequently Asked Questions

Q: The house has not been transferred yet. Who should book the disinfection and ozone treatment?
A: Before transfer, the house is generally still in the developer's care, so start by talking to the developer. Some projects arrange the work themselves, while others allow the buyer to bring in a service team. It depends on the contract and on what each project agrees to. WHD can work either way.

Q: Should disinfection be done before or after the walls are repaired?
A: Mud should be removed and damaged materials taken out first. Disinfection fogging and ozone treatment are best done after the main repairs, so they also deal with dust and spores stirred up during demolition. If repairs will take a long time, a first round can help stop the spread, followed by a second round just before move-in.

Q: The house is empty. Why does it still need ozone treatment?
A: Because the smell and the spores live in the air, the walls and the building materials themselves. Ozone reaches places that wiping and mopping cannot, and an empty house actually allows the gas to spread more evenly.

Q: How soon can we go back in after ozone treatment?
A: The house must be ventilated first so the ozone can break down. The team will advise on timing based on the size of the house and the concentration used. Nobody, including pets, should be inside, and plants should be removed, during treatment.

Q: If the walls are still damp, will disinfection fogging help?
A: Fogging helps reduce germs on surfaces, but it does not dry the walls. If materials are still heavily saturated, they should be removed or dried first; otherwise mold may return.

Q: The air conditioners are already installed. What should we do?
A: If the outdoor unit or any part of the system was submerged, have an air-conditioning technician check it before switching it on. Indoor units should be cleaned before you move in. Our team adjusts the ozone dose for rooms that contain equipment.

Q: Is the new-paint smell also something ozone can help with?
A: Many new homes carry a lingering smell from paint and adhesives. Ozone treatment can help reduce these odours as well; see our page on ozone treatment for chemical residue and odours.

A New Home Should Start with Clean Air

Talk to the WHD team as soon as the water goes down. We coordinate with buyers and project teams in Bang Sao Thong and the surrounding areas of Samut Prakan.

View 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 odours and chemical residue
• Master Ozone Generator
• All articles

Health reference: World Health Organization (WHO): Floods · Department of Health, Thailand