Complete Guide to Aluminium Window Waterproofing: When to Act & What It Costs

Rain pooling on your window sill after a typhoon, water stains spreading along the wall near your window frames, or mould beginning to appear on surrounding surfaces — these are all signs that your aluminium windows' waterproofing has started to fail. Addressing waterproofing works promptly not only stops the leak, but prevents moisture from penetrating the wall structure, saving you from far costlier repairs down the line. Typhoon season in Hong Kong is the ultimate test of any window waterproofing system, and the wisest approach is to inspect and act before the storms arrive.

What Are the Warning Signs of Window Waterproofing Failure?

Hong Kong's humid, rainy climate — with typhoon season running from May through November — places enormous stress on window waterproofing systems year-round. If you notice any of the following, it is time to seriously consider waterproofing works:

Silicone rubber weatherseals turning hard or shrinking: The weatherseal is the first line of defence against rainwater. Once it hardens or shrinks, gaps form and water finds its way inside. This is especially common in older private flats and HOS estates

Window silicone dissolving or peeling away: Deteriorated or peeling silicone along window glass edges means the waterproofing layer has already failed, leaving every gap exposed to rain

Loose or detached window handles: A window that cannot close properly leaves your home fully exposed during typhoon season, and leakage can escalate rapidly under strong winds

Oxidised window hinges: Oxidisation on hinges creates subtle gaps between the window sash and frame, providing an entry point for moisture

Water stains or mould on walls near window frames: These are visible consequences of existing water ingress — mould will continue to spread if left untreated, affecting your family's health

Ignoring these issues over time allows moisture to penetrate the concrete structure and damage internal reinforcement, making eventual repairs far more expensive than acting early with proper waterproofing works.

What Does Aluminium Window Waterproofing Involve?

Window waterproofing is rarely a single step — it typically addresses multiple points of failure at once. Amgen Windows' waterproofing works cover the following:

Replacing silicone rubber weatherseals: Removing hardened or shrunken old seals and fitting new high-durability weatherproof seals to ensure a tight fit between window sash and frame

Re-applying external silicone sealant: Stripping deteriorated silicone from window frame joints and re-sealing with professional outdoor-grade weatherproof silicone to block all entry points for rain

Replacing window hinges: Using Amgen-brand 304 stainless steel hinges, tested to 50,000 open-close cycles with a lifespan exceeding 30 years, ensuring the sash presses firmly against the frame at all times

Replacing window handles: Repairing or replacing loose or oxidised handles to ensure the window locks securely and cannot be pushed open by strong winds

Four-Component Works (四寶工程): Includes replacing window hinges, handles, interior and exterior weatherseals, and re-applying silicone — from $250, the most comprehensive preventive waterproofing package available

Complete Renovation Waterproofing Works: For older buildings or full-flat renovations, all window frame joints and external wall junctions are treated simultaneously, backed by a three-year workmanship warranty

These services can be combined based on your windows' condition. A formal quote is only provided after an on-site assessment — no hidden charges. Upon completion, our team provides before-and-after photos of replaced components so you can see exactly what was done.

Do Private Flat Owners Need to File a Declaration for Window Waterproofing Works?

Owners of private flats, HOS flats, or residential estates should be aware of Buildings Department requirements when carrying out aluminium window works. Requirements differ based on the type of work involved:

Maintenance and repair works (such as replacing weatherseals or re-applying silicone sealant) fall under routine upkeep and generally do not require a Buildings Department declaration. Owners can engage a contractor directly.

Full aluminium window replacement must comply with Class 2 Minor Works declaration requirements and be submitted by a licensed contractor. Amgen Windows holds licence number MWC 316/2021 and handles all declaration procedures on your behalf, so you do not need to deal with the paperwork yourself.

If you have also received a Mandatory Window Inspection notice, you can arrange for a qualified window inspection company to handle both the inspection and documentation in one visit — a convenient one-stop solution that also allows for a comprehensive assessment of your windows' overall condition.

Real Case Study: Waterproofing Works for a Tin Shui Wai Flat

A private flat owner in Tin Shui Wai reported that every typhoon season without fail, water pooled on the window sill and large water stains appeared on the surrounding walls — a problem that had persisted for several consecutive seasons. After an on-site inspection, our team identified three root causes: the silicone rubber weatherseals had fully hardened and shrunk, the window silicone had dissolved and peeled away, and loose handles meant the window sash could not close properly.

Our team arranged the Four-Component Works, replacing hinges and handles, renewing all interior and exterior weatherseals throughout the flat, and re-applying weatherproof silicone. The day after the works were completed, a Yellow Rainstorm Warning was issued — and not a single drop came through. The issue was fully resolved. The entire job was completed in half a day, with clear and transparent pricing, requiring no major renovation works.

Waterproofing Works: Price Reference

Service	Starting Price
Four-Component Works (hinges + handles + weatherseals + silicone)	From $250
Complete Renovation Waterproofing Works	From $2,000
Mandatory Window Inspection & Documentation	From $250
Emergency Repair (Typhoon Season, 24/7)	Quoted on-site

Final pricing depends on the number of windows, their size, and existing condition. We recommend booking a free on-site assessment so our team can inspect the windows thoroughly before confirming an accurate quote.

Frequently Asked Questions

Does window waterproofing require scaffolding?

The vast majority of window waterproofing works can be completed from inside the flat, including replacing weatherseals, re-applying silicone, and replacing hardware components — no scaffolding needed. Scaffolding is only considered when works involve large-scale external wall repairs or new window installation, and this is assessed case by case depending on the floor and scope of work. Our team will advise clearly during the on-site assessment whether scaffolding is required and what the associated cost would be.

How long does the waterproofing warranty last?

Amgen Windows' Complete Renovation Waterproofing Works comes with a three-year workmanship warranty. The 304 stainless steel hinges used in our Four-Component Works have a service life exceeding 30 years. For silicone sealant and weatherseals, durability depends on the environment and maintenance, but we generally recommend re-inspection every 5 to 8 years — replace as soon as hardening or shrinkage is detected to prevent seepage from recurring.

Can waterproofing works be done before a typhoon?

Before typhoon season arrives is actually the ideal time for waterproofing works. That said, the typhoon season (May to November) is also the peak period for maintenance requests, and our team's schedule fills up quickly — early booking is strongly recommended. If you discover leakage after a typhoon signal is already hoisted, Amgen Windows operates a 24/7 emergency repair service and can respond promptly.

Act Early — Stop Window Seepage Before It Gets Worse

The longer window seepage is left unaddressed, the deeper the wall damage becomes — and the higher the repair bill climbs. Amgen Windows offers free on-site inspection and quotation services across all 18 districts in Hong Kong, with emergency repair services available throughout typhoon season.

WhatsApp us at 6586 3435 to enquire, and arrange a free assessment at your convenience.