Jürgen Daub is pleased that Deventer has managed to get a sealing profile ready for series production that makes it possible for window manufacturers to avoid costly disputes with customers, homeowners and tenants in many cases.
His responsibilities include Research & Development at Deventer. Used as a central gasket, the new diffusion-open sealing profile improves moisture removal in the hardware rebate in such a way that it can be described as a “true revolution in the fenestration industry”. Daub explains that the problem of mould growth in the rebate may be a thing of the past if the new profile type gains traction as a central gasket.
Central gasket as the focus of the ift
Back in 2009, ift Rosenheim set out a key fundamental rule for constructing a window with optimal structural physics: “The central gasket must be more diffusion-open than the overlap gasket on the room side.” Over the years, the institute has investigated cases where moisture in the window rebate caused damage. The institute is seeing an increasing number of cases where this moisture came from sources inside the building, instead of outside.
It’s therefore indisputable that the rule stipulated in 2009 makes sense. But it’s remarkable, to say the least, that this issue had been largely ignored until that point – believes Daub.
Against the backdrop of this fundamental rule, Deventer initiated an extensive research project which, die to clearly being highly relevant, received funding from the “Central Innovation Programme for Small and Medium-Sized Businesses” (ZIM) federal initiative.
A window with added value
How does a sealing profile have to be designed so that a window is still protected against rain and wind, heat loss and noise yet so that moisture can diffuse out of the rebate via the central gasket? Deventer found the response to this question while working on the research project. The sealing profile innovation that was developed has since been protected by a patent and can be produced to be compatible with all common profile systems.
If window manufacturers have the confidence to charge customers a little bit more for the real added value that they explained to them, Deventer is ready to take on the role as a reliable supplier to them.
Reducing moisture
Mould can form when the air humidity on a surface is around 80% or more for three days.
After this time, fruiting bodies are formed, which look like a black bloom – explains Daub.
There is therefore a “critical moisture value” which promotes mould growth in the window rebate, for example. This is why Deventer simulated the effect of the seasons, temperature fluctuations and moisture formation in various window profiles using different gaskets on climate difference test rigs at the Fraunhofer Institute in Stuttgart. With a newly developed TPE gasket, the company ultimately managed to reduce the amount of moisture in the hardware rebate by up to 12%. It’s no exaggeration to say that this changes everything.
Making diffusion possible
Daub describes the development task as follows: We had to ensure that our new gasket would keep the air humidity in the window rebate below 80% at all times if possible. This is the case when it’s possible for the moisture to dry at all times, except for very wet weather conditions.
The company was therefore looking for a central gasket that enables rebate ventilation provided that the natural requirements for diffusion are met, in other words when the outside air is drier than the air in the window design.
Daub summarises the research work as follows: Our research project achieved the best conceivable outcome, as we finally specified the properties of the optimal sealing profile in this context and managed to prove its effectiveness in a laboratory.
Greater reliability for old and new buildings
Manufacturers who want to protect their customers and end users from unpleasant discussions about “black spots” in windows are advised by many experts and specialists to, in future, equip their windows with a central gasket that is actually capable of diffusion.
With the perfect components, our industry can manufacture building elements that are more capable of tolerating homeowners’ suboptimal ventilation habits – emphasises Daub.
This is set to become even more important as, in future, most windows will continue to be installed when renovating buildings that cannot be retrofitted with an automatic ventilation system to prevent risks.
The aim should be to construct new windows with correct structural physics so that their gasket level does not have to be subsequently modified and interrupted to reduce vapour pressure.
