Cold aluminium windows are one of the biggest drains on a Central North Island home's warmth, and one of the easiest to fix without a full renovation. Retrofit double glazing replaces the single pane in your existing aluminium frames with a thermally efficient double-glazed unit, so you keep your current joinery and get the performance upgrade underneath.

It's a fast, low-disruption way to cut heat loss, reduce condensation, and quieten a home down, without the cost or mess of replacing the frames themselves. Most homes can be retrofitted in a matter of days, and the result sits invisibly within your existing window and door openings.

As CNI's Altherm specialists, we bring the same thermal-performance rigour to retrofit glazing that we apply to full joinery installs. We'll assess your existing frames on-site to confirm they're a good candidate for retrofit, talk you through Low-E glass options, and give you a clear, accurate quote before any work begins.

Get in touch to find out if your home is a good fit for retrofit double glazing.

Apex Windows supplies and installs glass and aluminium balustrades for residential and commercial projects throughout the Central North Island. Whether for decks, stairs, pool areas, or architectural features, our balustrades are designed, specified, and installed to the same standard as your joinery,  powder coat matched, code compliant, and built to last. We use Juralco balustrade systems, one of New Zealand's most experienced balustrade manufacturers, with systems engineered and tested to exceed the NZ Building Code and backed by a 5-year product warranty.

Apex Windows supplies a full range of window and door accessories to complement your joinery installation. Choose from modern hardware options including stainless steel handles, multi-point locking systems, and stylish entrance door hardware across our Altherm range. Our full suite of powder-coated and anodised colour finishes ensures every accessory matches your joinery perfectly. Ask our team about accessory options when discussing your project.

Apex Windows supplies and installs frameless and semi-frameless glass shower enclosures for residential and commercial projects. Our shower installations use precision-cut, toughened safety glass fitted to a clean, modern finish; complementing your bathroom design without compromising on durability or compliance. Available in a range of configurations to suit new builds and renovations throughout the Central North Island.

Glass splashbacks offer a sleek, low-maintenance alternative to tiles, with no grout lines and easy-clean surfaces. Apex Windows supplies and installs toughened glass splashbacks for kitchens, bathrooms, and laundries in a wide range of colours and finishes; custom-cut to your specifications and fitted by our team across the Central North Island.

Apex Windows works with commercial clients across the Central North Island on interior glass and aluminium fitout projects — including partitions, frameless glass walls, shopfronts, and office glazing. Our commercial interior solutions combine precision fabrication with professional installation, meeting all relevant NZ Building Code requirements. Talk to our team about your project requirements.