January 22, 2025

What Are The 7 Most Important UPVC Window Features?

7 “Must Have” replacement UPVC window features

What follows is simply our opinion. But if you are about to get some new or replacement windows, then we consider the following UPVC window features or “specs” to be the minimum standards to aim for.

It won’t be a surprise if not everyone agrees with our assessment, especially those who are driven by the need to get the cheapest double glazing.

However, if you want to fit a value for money UPVC window product that works well and lasts a decent length of time, this list can be for you.

Number 1: Installation

The installer is one of the first things to look at. No matter how good the windows are that you buy, if they are badly fitted they won’t be effective. It could well cost you a significant amount of time and money to rectify any issues caused by poor installation.

Look for a FENSA OR CERTASS registered contractor. By working with a registered contractor, once the work is complete, you will be issued a Building Control Compliance certificate. This certificate is going to be needed when you sell the property later on. FENSA & CERTASS also regularly asses their members in order to maintain standards across the board.

Number 2: UPVC Frames / Profiles (A)

The frame profiles themselves should be multi-chambered. 2 or 3 chambers are not really good enough, 5+ is better. Frame chambers also allow for metal reinforcing that stiffens the profile, reducing deflection and warping.

Multiple chambers allow for air to be trapped, aiding insulation by preventing “mini-convection” currents moving the air around inside the frame.

Frame thickness should be at least 70mm.

Number 3: UPVC Frames / Profiles (B)

This might be seen as not so “environmentally friendly” but recycled UPVC can have discolouration issues. Virgin UPVC is regarded as staying whiter for longer due to better handling of Ultra-Violet Light.

Number 4: UPVC Frames / Profiles (C)

Mechanical joints (screwed) on the corners of the windows have a history of allowing gaps to form over time. Any gap in the joints will severely reduce the energy efficiency of the window. Gaps can also allow for water ingress causing internal damp problems.

Fully welded joints are the best solution.

Number 5: Guarantees.

There should be a minimum product guarantee of 10 years. This warranty should specifically cover warping, splitting or discolouration from date of the window installation.

Working with FENSA or CERTASS installers, your certificate will signify that the any warranty is insurance backed.

Insist on a workmanship warranty. In the event there are “teething problems” this will clarify the process and responsibility for rectifying any issues.

If you are asked for a deposit, then insist on an Insurance Backed Deposit Guarantee (you get all this with a FENSA approved installer).

Number 6: Glass & Glazing

  • Where any glass is fitted in a high risk area, it must be tempered safety glass.

See image below.

  • You should also have included Low-e glass, which boosts energy efficiency.
  • 28mm sealed units are recommended.
  • Gas filled sealed units are recommended. (Argon is cheapest, but Xenon is more efficient)
  • Internal glazing beads for all the glazed areas.

Number 7: Locks, Hinges & Handles,

Multi-point locking systems are the best and should be included. Any handles fitted should be checked for proper fitting & quality. Each handle should have its’ own key operated lock.

Hinges should be fitted with stainless steel screws, not zinc coated. This will stop any corrosion or rusting of the fitting screws. Also the screws themselves should be long enough to give proper grip into the frame.

UPVC Window Features: Bonus Tip

Any consumer protection “guru” will advise shopping around for prices & providers before buying. This is especially true in the double glazing market because it is so competitive.

It is essential to get at least 3 or 4 written quotes from different installers so that you can get a good comparison of the “market prices”.  Remember, if the deal looks too good to be true, then it probably is.

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