When most people start thinking about new windows or doors, they spend a lot of time on the aesthetics, such as styles, colours, and configurations. But here's something that doesn't get talked about nearly enough - the installation process matters just as much as the product itself. Even the best aluminium windows can underperform if they're not measured, manufactured, and installed correctly.
At DuCo, our aluminium window installation process has been refined over more than 50 years. Every step is deliberate, designed to eliminate error and deliver a result that's weathertight, thermally efficient, and built to last. Here's exactly what that looks like from start to finish.
Stage 1: Initial Enquiry & Quote
Every project starts with a conversation. For straightforward jobs, we'll ask you to send through photos and basic measurements of your existing openings, giving us enough to provide an initial window replacement quote (subject to an official site measure) and sense-check the scope of your project.
For larger or more complex projects, we'll arrange a site visit upfront. Either way, the information gathered at this stage sets the tone for everything that follows. You can submit your enquiry and photos directly through our contact page to get the ball rolling.
Stage 2: Site Measure
This is the most important step in the entire process, and it's one we take seriously. DuCo's preferred approach is always an in-person site measure, because custom joinery is made to exact dimensions, and there's simply no off-the-shelf fallback if something doesn't fit.
During the site measure, our team checks opening dimensions, assesses the existing framing, and flags any complications - things like existing flashing details, timber surrounds, or joinery types that need special consideration. A final measure is completed before manufacturing begins, confirming all specifications - including your chosen colours, finishes, and hardware - are correct before a single frame is cut.
If you're investing in made-to-measure windows, this step is what protects that investment.
Stage 3: Manufacturing in our Cambridge factory
Once measurements are locked in, your joinery goes into production at our premises in Cambridge, Waikato. Every frame is cut, assembled, and glazed in-house, which gives us direct control over quality, lead times, and consistency across your project.
This is also where product choices come to life. Depending on your project's thermal performance requirements, your custom joinery may include options like thermally broken aluminium frames or Low-E glass, both of which significantly improve a home's energy efficiency. If you're building new or planning a major renovation, it's worth understanding how these choices affect your home's overall performance. We cover this in more detail in our guide to improving new build energy efficiency without compromising on design.
Stage 4: Delivery & Site Preparation
When manufacturing is complete, your joinery is carefully packed and delivered to site. To keep installation running smoothly, there are a few things worth organising beforehand.
Internally, our installers need a clear work area around each opening - furniture moved to the centre of the room, curtains removed, and any fragile items well out of the way. Externally, we'll need vehicle access for delivery and potentially space for a skip bin while we work. A little preparation goes a long way in keeping the job on schedule.
Stage 5: Installation
With everything on site, installation begins. For replacement projects, our team will remove existing joinery and dispose of it responsibly. Openings are then checked and prepared before the new frames are fitted.
Where required, we'll also install new flashings and fit timber trim or architraves to finish the openings cleanly. This isn't just about aesthetics, correct flashing detail is a weathertightness requirement under Clause E2 of the NZ Building Code, which controls how buildings must be protected against external moisture. Our installers work to these standards on every job.
If you're wondering how to prepare your home for installation day, we've put together a full guide on what to do before, during, and after your aluminium window replacement or install.
Stage 6: Final Seal & Weatherproofing
The last step is also one of the most crucial. Once frames are in, every opening is sealed internally and externally, closing off any gaps that could allow moisture to enter, draughts, or heat loss.
Skipping or rushing this step is one of the most common causes of long-term window problems, such as heavy condensation, cold spots, and in worst cases, structural damage from water infiltration. A proper seal is what turns a good installation into a genuinely weathertight window system. Our team completes a final check before leaving site to make sure every detail is right.
Ready to Get Started?
At Duco, we're not in the business of supply-and-drop. Every aluminium window installation we carry out, whether it's a full new build or a single room replacement, goes through the same careful process, because the details matter.
If you're thinking about new custom windows or doors for your home, the best place to start is a site measure. Get in touch with the Duco team to get the conversation started, or download our Guide to Windows & Doors for everything you need to know before making a decision.
