At Nova Trade Frames, we know from experience that most issues with trade double glazed windows aren’t caused by the product, they’re down to minor ordering errors.
Whether you’re a seasoned installer or managing a multi-property build, this guide walks you through the most common pitfalls and how to avoid them. Getting it right the first time means happier clients, smoother installs, and more profit left in your pocket.
Trade Double Glazed Windows Mistake 1. Incorrect Measurements
Let’s start with the big one. Measurement mistakes are the number one reason why windows don’t fit on the day of install. Common problems include:
- Measuring from the plaster line rather than the brickwork
- Not allowing fitting tolerance (deducting 10mm for adjustment)
- Assuming the opening is square
- Mixing up frame size and aperture size
A window that’s just 5mm too big won’t fit without taking out more brickwork. A window that’s too small will leave large gaps and compromise the fit.
How to avoid it:
Always measure brick-to-brick in three places for both width and height (top, middle, bottom), then use the smallest measurement. Deduct 10mm for fitting tolerance, and clearly specify whether the measurement is the actual frame size or the aperture size. If you’re unsure, double-check with your supplier before ordering.
“We see it time and time again, a great job delayed over 10mm. Taking an extra few minutes on the measurement can save hours later.”
— Scott, Director at Nova Trade Frames
Trade Double Glazed Windows Mistake 2. Confusing Hinge and Opening Directions
It sounds simple, but getting left and right opening directions mixed up is another common issue. The problem usually happens when the spec is written from an internal perspective, while manufacturers work from an external view.
Imagine a window designed to open outwards from the left.
If the order describes that from the inside looking out, you’ll end up with the opposite result.
How to avoid it:
Always specify hinge and handle positions from the outside of the building. Use clear terms like “left-hand opening” or “top-hung”, and include diagrams if needed. When in doubt, send over a sketch or photo to your supplier for confirmation.
Trade Double Glazed Windows Mistake 3. Overlooking Compliance with UK Building Regulations
Installing windows that don’t meet current building standards is a fast way to trigger failed inspections, unhappy clients, or even legal issues. All trade double glazed windows should meet Part L of UK building regulations for thermal efficiency. You may also need to consider:
- Fire escape routes (especially for upstairs windows)
- Safety glass requirements in doors or low-level glazing
- Trickle vents in habitable rooms
How to avoid it:
Make sure your supplier understands the latest regs and supplies frames that meet them as standard. At Nova, all of our uPVC windows are A+ rated and Part L compliant, with options to upgrade to laminated or toughened glass where needed. If you’re unsure, just ask, we’ll walk you through the spec.
Trade Double Glazed Windows Mistake 4. Forgetting Key Glazing and Hardware Details
Window installations are more than just frames. Forgetting about the smaller details can lead to delays, reordering, or disappointment when the product arrives. Common oversights include:
- Not specifying obscure glass for bathrooms
- Forgetting to request trickle vents or restrictors
- Ordering the wrong colour handles or finish
- Overlooking child safety features or fire egress options
How to avoid it:
Create a quick checklist of must-haves for every window order. Include glazing type, handle colour, vent position, safety features, and special requirements like easy-clean hinges or equal sightlines. A good supplier will prompt you for these, but it’s always worth double-checking yourself.
Trade Double Glazed Windows Mistake 5. Using the Wrong Type of Supplier
Not all suppliers are trade-friendly. Some companies offer “trade discounts” but also sell directly to homeowners. This means your clients can shop around, find similar prices, and potentially cut you out of the job.
Worse still, many retail-focused suppliers don’t understand the demands of trade work. Lead times are longer, communication is poor, and you’re often stuck waiting for stock that doesn’t arrive when you need it.
How to avoid it:
Choose a supplier that works exclusively with trade professionals and has a great reputation. At Nova, we’re trade-only, no retail customers, no undercutting, and no DIY quotes.
That means you stay in control of the pricing, the spec, and the schedule.
Trade Double Glazed Windows Mistake 6. Not Asking for Help When You Need It
You might be an experienced installer, but window specs are constantly evolving. Whether it’s a new regulation or a bespoke opening style, guessing can be risky — and expensive.
How to avoid it:
Work with a supplier who will support you, not just sell to you. At Nova, we’re happy to take calls, check drawings, or advise on tricky measurements. You’re not just placing an order, you’re partnering with a team that wants your install to go smoothly.
“We’re not here to tell people how to do their job, just to help them avoid problems we’ve seen before. It’s in everyone’s interest that the job goes right first time.”
— Scott, Director at Nova Trade Frames
Final Thoughts
Ordering trade double glazed windows should be a straightforward process — but the details matter. A small oversight in measurement, glazing, or hardware can turn into a big problem on site.
That’s why working with the right supplier, one who truly understands trade needs, makes all the difference.
At Nova Trade Frames, we specialise in helping installers, builders, and developers get it right. From made-to-measure frames and quick turnaround times to expert support on every order, we’ve built our reputation on being reliable, professional, and trade-first.
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