“The phrase ‘in next to no time’ was invented for this.”

The best news comes from Finstral: our minimally invasive mounting methods allow windows to be replaced in record time:

• without residents having to vacate their homes
• without construction noise and dirt
• without scaffolding
• without any masonry and painting works.

In an interview, Finstral expert Timo Sachse explains the exact procedure.

Against the backdrop of the climate crisis and high energy costs, the debate about modernising heating systems is very much on the agenda. But what about windows?

TSThey are everywhere. We don’t have to go down into the basement to find them. But, amazing though it is, they are still far too often overlooked. Naturally enough, the type of heating system, i.e. the means of energy generation, is very important. But the most sustainable energy of all is and remains that which is not consumed in the first place. And this is where Finstral’s modern, perfectly insulated windows come in: not only do they cut carbon emissions, they also save money that would otherwise, quite literally, be thrown out of the window.

So window refurbishment really does make sense in terms of energy efficiency. But surely the replacement operation itself is expensive, elaborate and time-consuming ... and requires well-insulated nerves, doesn’t it?

TSNot when Finstral installs new windows. It’s practically child’s play ... OK, windows are a bit too heavy for toddlers. (Laughs.) We prefer to use the expression “minimally invasive” to describe our methods.

“Minimally invasive”? That sounds like medicine and surgery ...

TSExactly. Doctors endeavour to use surgical techniques that do as little damage as possible to human tissue. Similarly, our ambition is to leave the masonry untouched when replacing windows. Because knocking open walls immediately involves time, effort and cost while causing noise and dirt. Plus you then have to rely on bricklayers and painters, in other words commission other tradespersons. In the vast majority of cases, you also need scaffolding. The affected residents have to move out and the neighbours get annoyed. All a big nuisance. Minimally invasive procedures, on the other hand, are low-impact – and faster. In both the operating theatre and on building refurbishment projects.

But how can that be done? Windows are built into the masonry, aren’t they?

TSOf course they are – and that’s the way they stay when we have refurbished them. Put simply, the ingenious trick behind Finstral’s installation method is to leave in place the built-in part of the old window – i.e. the existing frame. And simply to use it, so to speak, as a “support” for the new window. Now if that isn’t sustainable!

So does that mean my new Finstral window won’t have a new frame?

TSOf course it will ... and a premium-quality one! This is the only way our windows can meet the highest standards of insulation, security, soundproofing and so on. But we dispense with the laborious process of breaking out the old frame and plastering in a new one. No, we simply slide the new frame onto the old one and connect the two.

How exactly?

TSThe particular details depend on the original window, but the principle always remains the same. We cut back old wooden frames, slide the new frame onto this and screw it down. This is called “slide-on installation”. Our “slide-in installation” technique is used for existing uPVC or aluminium frames: after we have removed all the hardware, these are thoroughly cleaned. The new frame then slides into the existing one and is screwed down. And, for the sake of completeness, I should point out that, if the old window itself was installed in two stages, i.e. with a mounting frame built into the masonry, we can reuse this. In such cases, the old frame is simply unscrewed from the mounting frame and the new one screwed on. Of course, whatever model is being installed, the new window sash with the glass is fitted and everything perfectly adjusted at the end ... And two window installers always suffice! The building occupants waiting in the adjoining room hardly notice them. And wonder why they disappear again so quickly.

And why is that? How long does the replacement take?

TSFor slide-on installation, roughly two hours per window. For slide-in installation or fitting to a mounting frame, around one hour. The phrase “in next to no time” was invented for this. Nor should we forget that, in the course of replacing the windows, we naturally also reinstate the building connections.

The mechanics of a window replacement sound almost too good to be true. But what about the final appearance? Often, this should or must not change significantly on the exterior ... while, in the interior, the occupants may appreciate new colours or a different material.

TSI’m glad you asked that. With slide-in installation, the old frame remains visible on the outside: if our frameless Nova-line window sash is incorporated, you will not notice any difference in the façade composition! On the inside, however, you enjoy the full design freedom offered by our modular window range. With frames in uPVC, aluminium, glass or real wood. Even ceramics or alternative metals can be selected. Complemented by an elegant window handle. This vastly enhances the quality of the interior. In terms of functionality too, a wealth of options are available. With innovative shading devices in the coupled sash. Or with lightweight solar protection glass to prevent rooms from heating up. And so on …

But if windows are suddenly much better insulated than before, don’t you have to worry about mould growth?

TSNot if you simultaneously ensure controlled interior ventilation. Provision for this can be made by integrating the necessary features directly in the window frame. These cannot be seen or otherwise noticed, but nonetheless deliver the necessary air change.

Brand-new, more attractive, more weatherproof, more modern, offering ventilation, and quick and easy to put in place. Who can say no to windows like that?

TSOnly burglars. (Laughs.) Because, naturally enough, new Finstral windows offer a high level of security.