Liaocheng Industrial Steel Structure Metal Roof Repair Project: Huacheng Color Exposed Waterproof Coating “One-Cloth Three-Coat” Application Case

Roof leakage is a common issue in building maintenance. Traditional patch repairs often fail to provide a lasting solution. This case documents a systematic waterproofing renovation project carried out on a building roof in Liaocheng, using Huacheng Color Exposed Waterproof Coating in combination with the “one‑cloth three‑coat” application process.

Project Overview

The project is located in the urban area of Liaocheng, involving a building roof that has been in service for several years. On‑site inspection revealed that the original waterproofing layer had aged and cracked, with multiple leakage points during the rainy season, affecting the normal use of the building. The owner required a thorough waterproofing renovation without altering the existing roof structure.

Material Selection Basis

This project selected Huacheng Color Exposed Waterproof Coating as the primary material. The product is formulated with high‑quality acrylate multicomponent copolymer emulsion and vinyl acetate‑ethylene (VAE) emulsion as the base materials, compounded with various additives and inorganic fillers.

Its key technical characteristics are as follows:

Weather resistance: The cured film withstands outdoor exposure to sunlight and temperature variations, with a broad service temperature range of –15°C to 110°C.

Mechanical properties: Tensile strength ≥2.0 MPa, elongation at break ≥320%, providing excellent elasticity and crack‑bridging capability.

High solid content: Solid content ≥65%, enabling greater film build per coat and improved film density.

Bond strength: Bond strength ≥1.2 MPa on cement substrates, and ≥1.0 MPa on damp substrates, ensuring reliable adhesion.

Customizable colors: Available in six standard colors – pink, blue, yellow, grey, white, and green – with custom colors also available upon request, balancing both functionality and aesthetics.

Application Process: “One‑Cloth Three‑Coat”

The “one‑cloth three‑coat” process is a composite application method that incorporates a reinforcing carrier (polyester nonwoven or fiberglass fabric) into the waterproof coating system. This process allows the carrier fabric and the coating to work together under stress, effectively enhancing the tensile strength, tear resistance, and ability to resist crack propagation from minor substrate movements.

Substrate Preparation: Remove the existing damaged waterproof layer, dust, and loose particles from the roof surface. Repair and level cracks in the substrate. Treat inside and outside corners to a smooth radius of at least R30 mm, ensuring a sound, smooth, and dry substrate.

Detail Reinforcement: At critical details such as the base of parapet walls, drain outlets, pipe roots, and expansion joints, apply an additional reinforcement layer using the “one‑cloth two‑coat” method, with a minimum width of 300 mm.

Large‑Area Application Procedure:

The “one‑cloth three‑coat” process was carried out in the following sequence:

First coat (primer): Apply the first coat evenly by roller or brush at a thickness of approximately 0.3–0.5 mm.

Fabric lay‑in: While the primer is still wet (before full curing), lay the polyester nonwoven fabric over the surface. Press down with a trowel or squeegee to remove trapped air and ensure firm contact with the substrate. Overlap joints shall be at least 100 mm.

Second coat (intermediate): Apply the second coat over the fabric, ensuring that the coating fully saturates the fabric weave and integrates with the primer layer underneath.

Third coat (topcoat): After the intermediate coat is touch‑dry, apply the third and final coat to achieve a total dry film thickness of at least 1.5 mm.

The direction of application for each coat should be alternated (preferably perpendicular) to avoid missed areas.

Curing and Inspection:

After completion, the coating was allowed to cure naturally for 7 days, during which foot traffic and rain exposure were strictly avoided.

Acceptance was based on a post‑rain inspection or a 24‑hour water ponding test, with no leakage observed.

Results:

Following the above procedure, the finished coating surface was smooth, uniform in color, and firmly bonded to the substrate. After natural rainfall, no further leakage was detected, confirming that the renovation objectives were fully met.

This case demonstrates that for roof waterproofing renovation projects, the use of Huacheng Color Exposed Waterproof Coating in combination with the “one‑cloth three‑coat” process offers the following advantages:

• The reinforcing carrier layer significantly enhances the integrity and durability of the waterproofing system.
• The coating’s high elasticity and strong adhesion accommodate temperature‑induced substrate movement.
• The water‑based, cold‑applied system is environmentally friendly and easy to work with.
• The overall system cost is moderate, offering a balanced combination of performance and economy.

This solution is suitable for roof waterproofing repair and renovation projects on similar types of buildings.