A Story from the Field: Customers Need Repair Supplies, but the Store Needs Repairing First

Hia Chai has run a medium-sized building materials store on a main road in Plaeng Yao District, Chachoengsao, for almost twenty years. The front of the shop sells hand tools, paint, PVC pipes and plumbing fittings. Behind it stands a tall-roofed warehouse stacked with plywood, gypsum boards, steel bars, tiles and pallets of bagged cement. His regulars include local contractors and villagers who come in to buy whatever they need to fix their homes.

During the 2026 floods, water from canals and the surrounding low-lying land flowed into the shop and warehouse. It was not especially deep, somewhere between ankle and mid-shin height, but it stood for several days. Staff managed to lift part of the stock onto pallets, but the bottom sheets of every plywood and gypsum stack soaked through. Cement bags sitting on the floor absorbed water and set into solid lumps. Cardboard boxes holding electrical fittings turned to pulp.

When the water went down, Hia Chai wanted to reopen quickly, because the whole district needed materials to repair their homes. A few days later, though, opening the warehouse door released a heavy, damp smell. The edges of the plywood sheets had black spots and green fuzz. The lower gypsum boards showed blotchy rings of mold. Staff carrying stock started coughing and sneezing. A contractor who came in to buy supplies joked, "A building materials store with mold in its own warehouse? Are the goods you sell any good?"

That comment made Hia Chai realize that if he did not handle things properly, he would lose both stock and credibility. The same situation can arise at building materials stores across Plaeng Yao District, in subdistricts such as Plaeng Yao, Wang Yen, Hua Samrong and Nong Mai Kaen, and in neighboring districts of Chachoengsao reached by the floodwater.

Note: this story is an illustrative scenario based on problems commonly found after floods. It does not refer to any specific person or business.

Why Building Materials Grow Mold So Quickly After a Flood

Many building materials are porous and contain ingredients that mold loves. Plywood is made of wood veneers and glue. Gypsum board has paper facing on both sides. Packaging is cardboard. When these materials absorb water and are stacked tightly in a poorly ventilated warehouse, moisture stays trapped inside for weeks, creating perfect conditions for mold growth.

• Plywood and sawn timber: the edges absorb water fast; inner plies can swell, delaminate and grow mold along the glue lines.
• Gypsum board: the paper facing is food for mold. Once wet, the board softens and loses strength.
• Bagged cement: cement that meets water reacts and sets into lumps. It can no longer be used to standard.
• Cardboard boxes and labels: they disintegrate, grow mold and make the products inside look old, even when the product itself is fine.
• Wooden pallets: after soaking, they become a source of mold that spreads to new stock placed on top.

The warehouse itself adds to the problem. Tall stacks block airflow, metal roofs heat the air during the day and cool it at night, and condensation forms on cold surfaces. Without deliberate ventilation, humidity in a flooded warehouse can stay high long after the floor looks dry.

The Impacts Store Owners Need to Weigh Up

Health of staff and customers

Staff who move moldy plywood or gypsum boards breathe in large amounts of spores, which can cause coughing, sneezing and a blocked nose, or trigger allergies and asthma. Staff who waded through floodwater to move stock face a risk of leptospirosis if they had cuts; boots and gloves are essential, and anyone with a high fever or calf pain after wading should see a doctor promptly. Flooded floors and shelving can also retain bacteria from sewage, such as E. coli.

The store's credibility

People buy building materials to build or repair homes they will live in for years. If a customer installs plywood or gypsum carrying hidden mold, and a few months later the wall or ceiling breaks out in black patches, that customer will come straight back to the store. Strict sorting of stock protects your reputation for the long term.

Good stock at risk

If moldy stock stays in the same warehouse as fresh goods, spores drift onto the newly delivered batch. The damage keeps spreading, and every week of delay adds to the losses.

Time and business opportunity

The weeks after a flood are when demand for repair materials peaks. If the store has to close for a long time, or has to fix the same problem repeatedly, contractors and homeowners will go elsewhere and may not come back.

Common Approaches That Do Not Work

• Wiping mold off plywood or gypsum and selling it anyway: mold that has penetrated the material remains and will come back as soon as it meets moisture again. The safe course is to set it aside, not sell it.
• Sun-drying wet cement bags: cement that has reacted with water cannot return to its original state. Drying does not help.
• Spraying bleach all over the warehouse: the smell is harsh, it can corrode steel and metal fittings, and it does nothing about spores in the air.
• Running industrial fans: they help with drying but also blow spores from moldy stock onto everything else.
• Bringing in new stock straight away: if shelving and floors have not been disinfected, new goods are at risk of turning moldy too.

The Solution: Sort Correctly, Then Disinfect and Ozone-Treat with WHD

World Health Disinfection (WHD) provides disinfection fogging with Chemgene HLD4H, delivered by ultra-low-volume (ULV) foggers whose fine mist drifts up to high racks, between pallets and into warehouse corners. This is combined with ozone treatment, which helps destroy airborne mold spores and break down musty odors in enclosed areas such as a shopfront with roller shutters, stock rooms and the back office.

It is important to be clear: disinfection and ozone treatment restore the building, the shelving and the stock that is still in good condition. They do not make water-damaged materials fit for sale again. The team will always advise sorting out damaged stock first.

Step-by-step process for a building materials store

1. Site survey: the team checks the flood line, mold hotspots, the type of stock in each zone, warehouse height and ventilation openings.
2. Stock sorting: plywood, gypsum, cement bags, cardboard boxes and wooden pallets that soaked or show mold are moved out of the warehouse. Non-absorbent goods in good condition, such as steel, PVC pipes and tiles, are kept for cleaning.
3. Washing and wiping: remove mud, wash floors and shelving, wipe down retained stock and let everything dry.
4. ULV disinfection fogging: Chemgene HLD4H is fogged across the shopfront, warehouse, racking, floors, lower walls, staff toilets and office.
5. Ozone shock treatment: roller shutters and openings are closed so the space is as sealed as possible, and treatment is carried out zone by zone with no people, pets or plants inside.
6. Ventilation: doors and fans are opened until the ozone smell has faded, and only then do staff return.
7. Re-check and advice: the team checks odor and mold again and advises on storing stock off the floor and away from walls.

Ozone safety: concentrated ozone is harmful to the respiratory system. During treatment there must be no people, pets or plants in the area. The team closes the space and posts warning signs, and the area must be ventilated before re-entry. Rubber goods or items with rubber parts, such as hoses and door seals, and sensitive electronics such as computers and receipt printers, are covered or moved, and the ozone dose is controlled to suit the space.

10 Reasons Building Materials Stores Choose WHD

1. Honest advice on sorting stock, protecting your store's reputation for years to come.
2. We use Chemgene HLD4H, without the harsh smell of chlorine.
3. ULV mist reaches high racks and pallet gaps that a cloth cannot.
4. Ozone treatment helps reduce airborne spores so they do not spread to new stock.
5. It breaks down musty odors in warehouses and stock rooms instead of masking them.
6. Zone-by-zone planning lets you keep part of the shopfront open while work goes on.
7. Rubber goods and electronics are covered or moved, and ozone is dosed in a controlled way.
8. Staff areas, toilets and the back office are treated at the same time.
9. Add-on mosquito spraying around warehouses where water still stands.
10. Easy to reach: call 065-556-6294 or LINE @whd268.

Before and After Restoring the Store and Warehouse

Customer Voice

"At first I hated throwing away all that plywood and gypsum, but the team explained that if a customer found mold after installing it, I'd lose far more. Once the stock was sorted, the warehouse fogged and treated with ozone, the smell was so much better. The contractor who teased me is back buying supplies as usual."
- Hia Chai, building materials store owner in Plaeng Yao (a character from an illustrative scenario)

Storage Practices After Restoration to Prevent Mold Returning

• Store plywood, gypsum and cement bags on plastic pallets or raised racks, never directly on the floor and not against the walls.
• Replace every wooden pallet that soaked in floodwater; do not reuse them.
• Leave gaps between stacks so air can circulate.
• Install exhaust fans or open vents near the warehouse roof.
• Rotate stock first-in, first-out so goods do not sit in the warehouse through the rainy season.
• Inspect the bottom layer of every stack weekly while the rain continues.
• Keep a dated record of cleaning and disinfection to show customers and contractors.

If your family home is attached to the store and was flooded too, see our page on residential ozone disinfection.

Advice You Can Pass On to Customers Repairing Flooded Homes

After a flood, the building materials store is where villagers most often go for advice. Giving them accurate information helps their repairs last and brings them back as loyal customers. Here are a few points worth sharing at the counter:

• Strip out before you rebuild: remove any gypsum, plywood or insulation that soaked in floodwater. Leaving it behind new panels hides a mold source inside the wall.
• Dry the structure completely: walls, timber frames and floors need time to dry. A moisture meter, if available, helps judge when the structure is ready.
• Disinfect before closing up: treat walls and framing before fixing new boards. For homes with musty smells or mold spread across several rooms, professional fogging and ozone treatment before repairs start help the repair last longer.
• Do not paint over damp walls: paint applied to damp plaster will bubble and peel, and mold will return beneath it.
• Choose materials suited to the risk: in areas prone to flooding, homeowners may prefer moisture-resistant boards or tiled lower walls. Recommend products honestly according to the manufacturer's specifications.

Customers appreciate a store that helps them avoid repeating the same repair next year. That trust is worth more than any single sale, and in a small district like Plaeng Yao, word of mouth travels quickly between neighbors, temples, markets and village groups.

A Practical Timeline for Getting the Store Back to Business

Every store is different, but most recoveries follow a similar sequence. Planning it in phases helps you keep cash flowing while the work is done properly.

Phase 1: Safety and assessment

Have an electrician check wiring and power outlets before switching anything on. Photograph damaged stock and record quantities for insurance or supplier claims. Wear boots, gloves and a mask when handling moldy materials.

Phase 2: Sorting and removal

Separate stock into three groups: clearly damaged (discard), unsure (set aside and check with the supplier), and sound (clean and keep). Remove damaged items from the building promptly so they stop releasing spores.

Phase 3: Cleaning and drying

Remove mud, wash floors and racks, and dry the building with ventilation. Open the warehouse whenever the weather allows.

Phase 4: Professional disinfection and ozone treatment

Once the space is clear and reasonably dry, WHD fogs the store and warehouse with Chemgene HLD4H, then carries out ozone treatment in zones that can be sealed. After ventilation, the team re-checks odor and mold.

Phase 5: Restocking and prevention

Bring in new stock onto clean racks and plastic pallets, keep air moving and inspect the lower layers regularly through the rest of the rainy season.

What the Team Looks For During the Site Survey

A good survey saves time and money later. When the WHD team visits a building materials store, it typically looks at several things before recommending a plan.

• The flood line: marks on walls and racking show how high the water reached, which tells the team which surfaces and which layers of stock were affected.
• Construction of the building: a closed shophouse with roller shutters behaves very differently from an open-sided steel shed. The degree to which each area can be sealed determines where ozone treatment is practical and where fogging and ventilation should do the main work.
• Hidden moisture: the backs of stacks, the undersides of pallets, the space behind counters and the base of internal partitions often stay wet longest.
• Stock mix: the proportion of absorbent goods (wood, gypsum, paper, cement) compared with non-absorbent goods (steel, PVC, ceramics, sealed tins of paint) shapes the sorting plan.
• Sensitive items: rubber products, electronics, cash registers and the computer used for stock control need to be identified so they can be covered or moved.
• Staff and customer flow: the team considers how to divide the site into zones so you can keep serving customers while the rest is treated.

With this information, the team can explain clearly what will be done, in what order, and what you need to prepare beforehand.

Keep Good Records: Suppliers, Insurance and Customers

A flood is stressful, and records are often the last thing on an owner's mind. Yet a few simple notes can make a real difference over the following months. Photograph damaged stock before it is removed, and write down quantities and batch numbers where possible. Some suppliers may offer support or exchanges for goods damaged in a disaster, and an insurer, if your policy covers flood damage, will usually want evidence.

Keep the dates of cleaning, disinfection and ozone treatment as well. When a contractor asks whether your warehouse has been dealt with, being able to say exactly what was done and when is far more convincing than a general reassurance. It also helps you notice patterns if mold ever returns in a particular corner, so the cause can be fixed rather than treated again and again.

Frequently Asked Questions

Q: If moldy plywood or gypsum is disinfected, can it be sold?
A: We do not recommend it. Materials that soaked until they grew mold may have lost strength, and contamination may have penetrated deep inside. Set them aside. Disinfection and ozone treatment are for restoring the building, shelving and stock that is still in good condition.

Q: Does ozone work in a tall, open warehouse?
A: Ozone works best in enclosed spaces. The team will survey the site and advise on closing openings or treating in zones that can be sealed. Open areas focus on disinfection fogging and ventilation.

Q: How long will the store have to close?
A: It depends on the size of the premises and how much stock needs sorting. The team can plan the work in zones so part of the shopfront stays open.

Q: Will the disinfectant cause metal goods to rust?
A: Chemgene HLD4H is used according to its label instructions, and the team will advise on wiping and drying metal stock after the work.

Q: Can cement bags that are only wet on the outside still be used?
A: Check whether the cement inside has formed lumps. If it has, do not sell or use it. If unsure, consult the manufacturer or distributor.

Q: Is it safe to keep sealed tins of paint and tile adhesive in the warehouse during treatment?
A: Sealed, non-absorbent containers can usually stay in place once they have been wiped clean. The team will point out anything that should be covered or moved during the survey, such as products with rubber seals or open containers.

Q: Our staff are still coughing after the clean-up. What should we do?
A: Make sure moldy materials have been removed from the building, keep the space ventilated, and give staff proper masks when handling remaining debris. Anyone with persistent coughing, breathing difficulty or fever should see a doctor. Professional disinfection and ozone treatment can then help reduce what remains in the air and on surfaces.

Q: Do you serve Plaeng Yao and nearby areas?
A: Please call 065-556-6294 or message LINE @whd268 to check the service area and book a survey.

Get Your Store Ready to Supply the Community's Repairs

Talk to WHD about sorting, disinfection fogging and ozone treatment for your store and warehouse.

View Disinfection Service - Click Here

Book Ozone Treatment - Click Here

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

Related Links

• Ozone treatment for odors and chemical residue
• Master Ozone Generator
• Chemgene HLD4H 750ml spray
• All articles

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