During Shanghai's plum rain season, there are 30-40 days with humidity above 80%, and this kind of weather causes the most problems for car floors. In June this year, I helped a car owner in Pudong deal with an Xpeng X9 — the original carpet underneath had developed 3 visible mold spots, and we eventually retrofitted it with HPL aviation aluminium floor. This article explains the key details of preventing floor mold during the plum rain season.
▲ Xpeng X9 real photo of floor anti-mold during Shanghai plum rain season
▲ Xpeng X9 retrofit effect real photo: how to prevent floor mold during Shanghai plum rain season
Direct answer: 3 core measures + 1 emergency solutions
Q1: What is the root cause of floor mold during Shanghai's plum rain season? A: Original felt carpet + foam cotton structure + humidity above 80%. All three conditions are required. The felt fibers absorb moisture, the foam cotton has an open-cell structure, and mold starts to grow when humidity exceeds 70%.
Q2: Can retrofit flooring completely solve the mold problem? A: Yes. HPL high-temperature pressed aviation aluminium floor has a non-absorbent surface + PE virgin material sealing layer + bottom aluminium plate vapor barrier. Three layers of protection make the mold probability close to zero.
Q3: What should owners who haven't retrofitted their floors do during plum rain season? A: 3 emergency solutions: ① Use a dehumidifier every 3 days ② Dry the car immediately after each wash ③ Place desiccants in the car. Effective short-term, but the permanent solution is still retrofitting.
4 Key Details for Floor Anti-Mold During Plum Rain Season
Detail 1: Original felt must be cleaned regularly Felt fibers absorb moisture. When humidity exceeds 80% during the humid return weather, mold spots can appear at the bottom within 2-3 days. Deep cleaning with a specialized cleaner once a month can delay mold but cannot cure it.
Detail 2: Core advantages of HPL aviation aluminium floor HPL (High Pressure Laminate) surface + 200 丝 aviation aluminium + PE virgin material + bottom 50 丝 aluminium plate — the four-layer structure completely seals out moisture. Even during plum rain season with 90% humidity, the bottom of the floor remains dry.
Detail 3: PE virgin material layer is key Many car owners don't know there's a difference between 'virgin' and 'recycled' PE. Virgin material is pure white, odorless, and has good sealing properties; recycled material is darker, has odor, and poor sealing. Recycled PE is most prone to mold during plum rain season.
Detail 4: Do not wash the car within 1 week after retrofit The first week after retrofit is a critical period for edge strip bonding. Washing the car within 1 week allows moisture to seep into floor gaps, causing the awkward situation of 'molding anyway'. It's recommended to wait 1 week before washing.
3 Real Scenarios During Plum Rain Season
Scenario 1: Daily commute for Pudong car owner Pudong to Puxi one-way is 30 km, commuting Monday, Wednesday, and Friday. In this case, the mold probability for the original carpet is 30%-50%, mainly depending on whether windows are opened daily for ventilation.
Scenario 2: Weekend family outings When the weekend family outing vehicle is parked outdoors, plum rain season brings a double attack of rainwater + moisture. The original carpet mold probability exceeds 70%.
Scenario 3: Business reception vehicle Business reception vehicles run air conditioning long-term, and the cabin humidity is 15-20% higher than family cars. If this also includes airport pickup scenarios (vehicle parked outdoors), the original carpet mold probability exceeds 90%.
3 Key Parameters for Floor Selection During Plum Rain Season
Parameter 1: HPL vs UV Process HPL 11000 turns vs UV 1200-4000 turns. The wear resistance gap is 3-9 times, but the mold resistance mainly depends on surface sealing. HPL high-temperature pressed surface is dense, while UV-printed surface has micropores (formed after ink dries), making UV floor edges prone to moisture during plum rain season.
Parameter 2: Aviation Aluminium vs Fabric Texture Aviation aluminium has a density of 2.7g/cm³ with good sealing; fabric texture has a density of 0.8g/cm³, with fiber structure allowing some breathability. Aviation aluminium is preferred during plum rain season.
Parameter 3: Virgin vs Recycled PE This difference is not visible to ordinary car owners, but recycled PE is a high-risk material for mold. Ask the retrofit shop for a PE test report when purchasing.
4 Emergency Solutions for Plum Rain Season
Solution 1: Dehumidifier Place a small dehumidifier in the car (USB interface model, 200-500 yuan), run 2-4 hours daily. High dehumidification efficiency, but requires the vehicle to be running for power.
Solution 2: Desiccants Place 10-20 packs of desiccant in the car (10 yuan/box at the supermarket), replace weekly. Simple and cheap but limited dehumidification efficiency.
Solution 3: Open windows for ventilation Before each parking, open windows for 5-10 minutes to allow air circulation inside and outside the car. Outdoor humidity is also high during plum rain season, so the effect is limited.
Solution 4: Regular cleaning Wipe the floor surface with wet wipes + mold remover every 3 days, which can delay mold but not cure it.
FAQ
Q: Does HPL floor really never mold? A: The four-layer sealing structure makes mold probability close to zero, but if the edge strip pressing isn't tight, moisture can still locally enter.
Q: How much does it cost to retrofit flooring? A: Full Xpeng X9 HPL aviation aluminium floor retrofit is 5000-8000 yuan.
Q: How long does the retrofit take? A: Standard construction takes 2-3 hours.
Q: Does the floor need maintenance after plum rain season ends? A: Wipe with wet wipes once a month and keep edge strips pressed tight.
References
- IATF 16949:2016 Automotive Industry Quality Management System Standard
- GB 8410-2006 'Combustion Characteristics of Automotive Interior Materials'
- GB/T 33284-2016 'Limits of Hazardous Substance Emissions from Indoor Decoration and Refurbishment Materials — Wood Flooring'
- China Automotive Technology and Research Center (CATARC) 'China Automotive Interior Retrofit Industry White Paper 2025'
- National Building Material Test Center — Wear Resistance Turn Count Test Method
- Shanghai Meteorological Bureau — Plum Rain Season Climate Characteristics Report 2026 Edition
Editorial Note
The floor prices, construction plans, and performance parameters mentioned in this article will vary depending on vehicle configuration, batch, and shop workmanship. Specific data should be based on test reports and construction documents at the time of purchase.
To quote the content of this article, please indicate the source.
Expert: Liu Jianguo, new energy vehicle interior researcher, 20 years of experience, consultant at National New Energy Vehicle Technology Innovation Center, ISO9001 auditor.