Difference between damp-proof and anti-mold coatings: functional positioning, material systems, testing standards, and applicable locations (damp-proofing managed as a structural layer; anti-mold managed by film performance)

Topic Positioning

This card clarifies the functional positioning, governing standards, and applicable locations of "damp-proof coatings (damp-proof layers)" and "anti-mold coatings", two often-conflated materials. The former solves vapor blocking (a physical problem), uses waterproofing-material systems, and is managed as a structural layer; the latter solves mold growth (a biological problem), relies on bactericides in the film, and is graded by film performance. For material selection, construction, and listing in indoor waterproofing, cleanrooms, food-industry premises, and rail-transit stations.

Core Conclusions

1. Different functional essences

• Damp-proof layer (damp-proof coating): blocks vapor penetration and capillary seepage. JGJ 298-2013 Technical Specification for Indoor Waterproofing of Housing, Clause 4.6.1: "Walls and ceilings should use waterproof mortar or polymer-cement waterproof coating as the damp-proof layer; floors of units without basements may use polyurethane waterproof coating, polymer-emulsion waterproof coating, water-emulsion asphalt coating, and waterproof membranes." Commentary: "In principle all waterproof materials in this code may serve as damp-proof layers; considering tiles or paint finishes on walls/ceilings, waterproof mortar or polymer-cement coating is preferred."
• Anti-mold coating: inhibits/kills mold via bactericides in the paint. GB 50591-2010 Code for Construction and Acceptance of Cleanrooms, Clause 4.3.3: "Coatings shall be water-, wear- and acid/alkali-resistant. Where anti-mold is required, bactericides shall be added and artificial inoculation per GB 1741 shall meet the requirements." Corresponding requirement: "Painted walls: for acid/alkali resistance, no blistering or peeling after 96 h immersion; scrub resistance >= 300 cycles without visible change. Anti-mold requirement is Grade 0 — no growth after 7 days of inoculation."
• Terminology: T/CCES 4-2019 Clause 2.0.7 — mold resistance means "the property of inhibiting mold growth and reproduction and killing vegetative and reproductive bodies of mold microorganisms".

2. Different testing and evaluation calibers

• Damp-proof layers: evaluated by waterproof-system performance indices (impermeability, bond strength) with structural control of thickness and up-turn height; "damp-proof layer materials are in principle the same as waterproof layers, only the thickness may be slightly lower" (DBJ/T 15-19-2020 Clause 5.4.7 commentary).
• Anti-mold coatings: graded by mold-resistance testing — artificial inoculation, Grade 0 the top; product standard HG/T 3950 Anti-bacterial Coatings. GB 50687-2011 Technical Code for Clean Rooms in the Food Industry, Clause 6.2.8: "Where rooms or key zones with relative humidity frequently above 80% or with steam operations are painted with anti-bacterial anti-mold coating, the mold-resistance grade shall reach Grade 0 of HG/T 3950; hazardous-substance limits shall comply with GB 18582; repaint regularly per service conditions." Commentary: "At 80% RH, regardless of temperature, mold will basically always grow" — anti-mold coating may then be applied.

3. Damp-proof layer setting and structural requirements (DBJ/T 15-19-2020 Clause 5.4.7) "Damp-proof design shall comply with: 1 Where a room has waterproofing requirements, damp-proof layers shall be provided on all walls and ceilings except those with waterproof layers; where the floor above is a water-related room, the ceiling damp-proof layer may be omitted; 2 Walls of drainage shafts or adjacent thereto should have damp-proof layers; 3 Damp-proof layer thickness per Table 5.4.7; 4 Walls should use waterproof mortar or polymer-cement coating; ceilings should preferably omit plaster and use polymer-cement coating; 5 Floors of non-water-related rooms without basements may use synthetic-polymer or polymer-emulsion coating; the damp-proof layer shall rise not less than 300 mm above the finished floor along the walls."

4. Parallel in classification, unified in workmanship, but not interchangeable T/CBDA 13-2018 Technical Specification for Decoration of Rail Transit Stations, Clause 9.1.1 lists "anti-mold coating, damp-proof coating, art paint, emulsion paint" in parallel as coating categories; Clause 9.2.1 uniformly requires: "1 Color, gloss, pattern, and damp-proofing per design; 2 Substrates firm, dry, clean; coating even and well bonded." Confusion points: (1) damp-proof != anti-mold — a damp-proofed surface with persistent condensation and organics still molds; dampness must be solved first; (2) anti-mold != damp-proof — anti-mold coatings generally lack structural vapor blocking; (3) listing caliber — damp-proofing is usually listed as a "damp-proof layer" structural item (same system as waterproofing, thickness may be lower; mind the fee caliber distinction), anti-mold as a performance requirement of the finish coating (noting grade and the GB 1741 / HG/T 3950 test basis).

Applicable Boundaries

• This card sorts functions and code calibers; specific thickness limits require DBJ/T 15-19-2020 Table 5.4.7 (values not expanded here).
• DBJ/T 15-19-2020 is a local (Guangdong) standard; other regions follow local standards; JGJ 298-2013, GB 50591-2010, GB 50687-2011 applications follow current editions and design documents.
• The Grade-0 requirement (no growth at 7 days) targets locations with explicit anti-mold requirements (e.g., RH frequently > 80% or steam operations), not a blanket rule.
• Material compatibility: where walls/ceilings will take tiles or paint, prefer waterproof mortar or polymer-cement coating, avoiding materials impairing subsequent finishes.

Further Reading

• JGJ 298-2013 Technical Specification for Indoor Waterproofing of Housing, Section 4.6 (4.6.1 material selection)
• DBJ/T 15-19-2020 Technical Specification for Building Waterproofing Works, Clause 5.4.7 and Table 5.4.7
• GB 50591-2010 Code for Construction and Acceptance of Cleanrooms, Clause 4.3.3 (testing per GB 1741; Grade 0)
• GB 50687-2011 Technical Code for Clean Rooms in the Food Industry, Clause 6.2.8 and commentary (Grade 0; GB 18582 limits; repainting)
• T/CCES 4-2019 Technical Specification for Multi-Functional Energy-Storage Luminescent Coatings, Clause 2.0.7
• T/CBDA 13-2018 Technical Specification for Decoration of Rail Transit Stations, Chapter 9
• Related test standards: GB 1741; HG/T 3950; GB 18582