The new AluK 77 Window System Reviewed

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Nick Dardalis

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On 17th October, AluK launched a brand new window system called the 77.  Everyone in the aluminium sector knows AluK as a systems company and as a hugely successful brand in the UK.

With many trade fabricators choosing AluK as their system of choice and even more installers deciding to sell it, AluK has a comprehensive range of aluminium windows and doors.

AluK has enjoyed phenomenal growth as a business in recent years and recently announced their move to even bigger premises in Newport. Their London Design Centre also plays an important role for the public, specifiers, architects and their customers.

The AluK 77 aluminium window.

aluk 77 window inside view.
AluK launches the new 77 Window system featuring slim lines, great thermal performance and smart detailing.

AluK’s new 77 window system is what is to be expected from a latest generation aluminium window. That is a product with good design, slim sight lines, low U-Values, impressive performance and a choice of opening options.

Make no mistake; this is not just a commercial window. AluK’s 77 window is a universal window suitable for any building requirement. There is no reason why the AluK 77 window cannot be used in refurbishments, new openings, high rise or low rise applications.

Integration with the wider range of AluK curtain walling and door systems is also possible with the 77 window.

Construction and design of the new AluK 77 Window.

Detailed sections of the window, fabrication and installation details are not yet available so our review here is based upon analysis of what is currently provided by AluK about this product.

The outer frame depth is 77mm making the windows suitable for the replacement of old timber or PVCu. The typical outer frame is 53mm on the inside face, 31mm on the outside face or 5mm less where an open out vent overlaps the frame. The overall sight line inside and out is 100.5mm.

Two outer frames are available, one 53mm high and a deeper, extended leg outer frame at 78mm high. The 78mm high frame features an additional clip on section that gives a picture frame effect to the window. Looking at the detail of this we would imagine this also acts as a weather bar where required.

Window mullions and transoms are available in two sizes, an 82mm mullion or a 96mm deeper section. Both offer a 33mm or 38mm sight line at the front depending upon whether there is a single or a double vent on the section. A further option exists for a reinforced box mullion to create large span windows or where the wind loads on the product are greater.

For an opening in window, you get a deeper vent section front to back by 10mm, but you’ll also get a narrower face at 95mm compared to 100.5mm.

It’s certainly slimmer than the 72BW window, but we’ve always believed a 100mm or so sight line is enough for a current generation aluminium window. If you want even slimmer, go for the AluK ST steel replacement or other steel replacement window system.

For those wanting large opening windows, a top hung vent will go to 1500x1800mm on both open in or out windows and a side hung vent at 838mm x 1800mm. You may ask who would have windows this large? More and more residential customers in bespoke extensions, not just commercial buildings. Many systems companies feature a large opening window in their showrooms today.

AluK offers an advanced thermal break with insulation upgrade.

We’ve seen many new window systems move away from the traditional flat and straightforward polyamide thermal break to more sophisticated variants or a different insulation altogether.

For example, Origin Twin Flush Windows are upgradable with Aerogel. Warmcore aluminium windows use a PVCu warm core. Senior PURe windows use polyurethane.

AluK has two polyamide strips creating a thermal barrier, each with four chambers. We imagine this is one detail that gives the window its excellent performance and profile strength.

Added to this is a centre seal. This is a gasket with five flanges and three chambers. The HI variant of the AluK 77 window sees a thermal insert between the chambered thermal breaks to add even better insulation.

What we see is that aluminium systems designers, aware of the limitations of aluminium in thermal performance, have to work on the thermal barrier itself. Some systems companies choose the biggest thermal break they can design. Others choose a different material; AluK has chosen something else again.

The window will be with a mechanical cleated construction that AluK says is easy to fabricate with no substantial tooling changes required.

A new, high-performance window by AluK.

When it comes to thermally efficient windows, AluK has usually provided windows to meet or exceed currently requirement within their product range.  Their existing suite already provides good thermal performance, with insulated profies and double or triple glazing available on most products.

AluK refers to the new 77 window as a superior aluminium window. Indeed it offers even better performance from an aluminium window. The U-Values of 1.2Wm2K to 1.4Wm2K using a 1.0 sealed unit.

A triple glazed AluK 77 window will meet 1.0 Wm2K to 1.2 Wm2K. The BRE Green Guide rating is an A or B Rated window.

AluK’s new 77 aluminium window opens in or out.

The 77 Window System is available as both an opening in (77IW) and opening out (77IWE) window. The opening inwards window comes only as a side hung open in and a bottom hung open-in window. The outward opening window comes as a top hung, side hung and bottom hung opening window.

The provision of an opening inwards window we think is a good decision by AluK. Outward opening casements may be the more traditional window but we feel a good aluminium window should offer both options. There is a tilt and turn option as well.

Both opening-in and opening-outwards variants offer an HI (High Insulation) upgrade for Overall, it is a superior window to the 72BW window that remains available.

Hardware choices for the various opening windows are multi-point or single point locks, locking handles, cam openers, butt hinges and of course, friction stays. You can also modify these windows to accept Teleflex gearing if desired.

Colour choices and finishes.

the 77 window system will come in the full range of colours with the bonus of anodised finishes.
The 77 window system will come in the full range of colours with the bonus of anodised finishes.

As you’d expect from a current generation aluminium window the full range of RAL colours or other powder coats will be available. It’s good to see that systems companies are offering anodised finishes alongside powder coating.

Anodising provides an excellent finish to an aluminium window and in many cases offers a better colour proposition. Anodised finishes can make aluminium look highly contemporary with a beautiful metal appearance. It’s a shame more systems companies don’t provide anodised windows.

You’ll also get the very appealing textured powder coated finish similar to the Smarts Sensations range.

Weather performance of the AluK 77 window.

For weather performance, AluK offers:

  • Air permeability Class 4 600Pa
  • Water Tightness 1050Pa
  • Wind resistance, 2400 Pa.

All AluK 77 window variants are SBD Compliant.

The window can be made in various types whether as stand-alone or couple windows. Aside from the obvious fixed pane windows, top hung and side hung, there are also multiple vent options, corner windows, windows with curtain wall outer frames and others. All of them are SBD compliant windows.

Our conclusion and review of the AluK 77 Window.

aluk_logo AluK has always designed good windows, and the new 77 is no exception. The profiles and overall appearance are contemporary, and it is very much a current aluminium window.

It is evident that AluK has created the 77 suite to meet not only future changes in the Building Regulations but the requirements for higher performance windows.  From what we see initially, it has the right balance of design, high security, thermal performance, weather performance and some attention to detail.

The thermal insulation is achieved thanks to 39 mm alveolar polyamide bars, enhanced even more by foam and insulation strips that provide a window cavity keeping cold out and the heat in.

The AluK 77 Window System also offers slim fixed lights with a face dimension of only 53mm, depending upon the sections used.

The integration into the AluK suite is logical, the availability of an inward opening window a great addition and you can also have a tilt and turn window.

Delve a little deeper, and you’ll also find that the AluK 77 window can also come as a single or double door, that we’ve not mentioned until now.

We like how AluK has made every window variant SBD compliant, and the option of anodised finishes is great.  There’s also an intelligent gasket expansion detail when you butt two windows up to each other saving money on an additional aluminium profile.

The likability of the window will also be in the reduced fabrication times and easier installation claimed by AluK.

AluK is firmly established as one of the well-known systems companies with a broad range appealing to both residential and consumer markets. We think this window is well designed, aesthetically sound and should sell well.  As more information becomes available we will review it again.

(Images and section drawings from

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