Vietnam’s weather, with heavy rainfall during the rainy season, can significantly impact buildings constructed with metal roofing sheets. If the roofing system is not properly installed or lacks adequate maintenance, it can lead to serious damage. Therefore, reinforcing metal roofs with appropriate anti-leak solutions from the beginning will help increase durability and improve resistance to harsh weather conditions.

Industrial buildings using metal roofing

Causes of Metal Roof Leakage

Below are some common causes of leaks in metal roofing:

• Poor-quality installation during construction.
• Using low-quality roofing sheets that deteriorate quickly.
• Long-term corrosion caused by prolonged exposure to rainwater.
• Water seeping through screw holes over time.
• Scratches during transportation and installation that later rust and create holes.
• Falling debris from above—such as branches or items dropped from nearby tall buildings—damaging the roof.
• Water overflow at joint waves where roofing sheets overlap.
• Leakage at the boundary between two adjacent roofs.

How to Effectively Fix Leaks in Industrial Metal Roofs

The first step is to identify the exact locations of leaks. This allows you to choose the most suitable and cost-effective method. Below are some tips to help locate leaking points:

• Inspect visually with the naked eye.
• Check all areas of the roof you suspect may be leaking.
• Observe from below to determine drip points.
• Check whether screws are worn or corroded.
• Look for areas with severe rust.
• Always identify the exact leaking point before taking corrective action.

6 Methods to Fix Industrial Metal Roof Leaks

1. Replace Rusted Screws and Reinforce Loose Fasteners

If roofing screws or bolts are damaged, they must be replaced. Remove old screws using the proper tools and install new ones one by one.

Do not remove multiple screws at once, as this can shift the roof sheets and create new problems.

If screw holes have expanded, use sealant or waterproof tape to cover them. Apply silicone around rafters and screw points to ensure complete sealing—this is a low-cost yet effective method.

2. Fix Leaks at Sunken or Perforated Areas (Wave Crest or Trough)

Roof leak repair – Metal roofing sheet punctured in the middle of the panel

Handling punctures located in the middle of the roofing sheet waves: Many cases of roof perforation occur in the center of the sheet due to careless screw installation during construction, or scratches caused during transportation that later corrode and create holes.

Solutions:

Small holes: Apply silicone or adhesive waterproof tape.

Larger holes (5–10 cm):
– Clean the surface thoroughly.
– Apply a large waterproof membrane (temporary 1–2 years), or
– Fasten a small metal patch over the hole using screws or rivets and apply sealant around the edges for long-term durability.

This is one of the most common and effective repair methods.

3. Fix Leaks at Overlapping Roof Joints

Re-tighten or add screws and reinforce with waterproof sealant.

These joints are where two sheets overlap. Over time, wind and rain can loosen screws or lift the sheet edges, causing water to flow backward into the joints.

4. Fix Leaks Caused by Deformed or Sunken Roof Waves

If the roofing sheet is bent, creating a low spot where water collects:

Solution:
– Drill a screw at the crest of the sunken wave.
– Use a wire to pull the bent section back to its original shape.
– Do this slowly and avoid stepping on the weakened area.
– Add a 3 cm metal support beneath the dent to prevent it from sinking again.

5. Fix Leaks at Roof-to-Wall Junctions or Between Two Roofs

If your roof leaks at these junctions, you can apply either of the following:

• Waterproofing the metal roof at the wall joint: Use a cement–mortar mixture to fill and seal the gap between the two buildings to prevent rainwater from flowing into the joint.
• Use waterproofing tape for metal roofs to seal the joint between the two houses, or use metal sheets (1000 mm / 2000 mm) cut in half to 500 mm, then fasten them securely with nails or roofing screws to prevent wind uplift. This method fully resolves leaks at the roof-to-roof joint — highly effective and easy to apply, especially for metal roof repairs during the rainy season.

Using sealant in leak prevention

6. Repair leaks caused by acid corrosion from rainwater

Before applying anti-rust paint, clean the roof surface thoroughly. Then use a spray gun or brush to apply oil-based paint, helping protect the roof from corrosion.

Common Materials Used for Metal Roof Leak Prevention

Depending on the actual condition of your metal roof, you can choose suitable waterproofing materials for metal roofs, tile roofs, or fiber-cement roofs. Below are some commonly used materials:

• Metal roof waterproofing tape
• Leak prevention using gasoline mixed with foam
• Silicone sealant for metal roofs
• Anti-leak metal flashing sheets
• Specialized roofing screws
• Waterproofing membrane for metal roofs
• Self-adhesive waterproofing sheets for metal roofs