Air and Weather Seals for High Performance Window Installs

Our favourite type of project we undertake is one where we’re able to offer a complete survey, supply and installation service. It means we’re in complete control over everything we need to be to ensure the products we provide are installed in the best possible way, without any misunderstandings.

Ultimately, spending money on a high performance airtight window is pointless if the installation is not of equivalent quality and longevity. In the customer user guides for a lot of our products, there’s a long section explaining the importance of understanding the level of airtightness the new products will provide. In some cases, it’s almost written as a warning to remind people who aren’t used to having such an airtight home – it becomes far more important to open windows regularly when that accidental airflow through older doors and windows suddenly doesn’t exist.

So, to match this level of care, our high-performance windows are always treated to a high-performance installation.

Long-lasting Weather Seals

The photograph below shows a sample of expanding tape in between the window and the bronze stone. This is a critical part of our installation, as it acts as a weather-tight movement joint. Buildings and windows naturally expand and contract so, by using expanding tape, the area around your airtight high performance windows remains protected against the British weather.

Compriband tape installed STM Tinium windows

Image from our Modernisation of Large Cotswold Family Home gallery

In most situations, compriband tape sorts out uneven surfaces beautifully – leaving a black shadow gap around the window. But, in some situations, additional steps may need to be taken.

For example, using compriband with rough dressed stone requires a little more thought. Stone can be incredibly uneven, to the point where a window frame could be theoretically touching the edge of one stone, but have a gap of 20mm right underneath that needs to be filled. This is a situation where compriband may not be able to solve the issue alone. Where this is the case, we often suggest that these rough stone openings are straightened out via a small amount of pointing – this reduces the massive difference in tolerance gaps and provides a neat surface for the expanding tape to seal to.

In the photo below, we can see another line of black expanding tape against a white render. Normally, you would see render being applied directly onto the face of a window which, in some cases, is suitable. Here though, that flexible tolerance is retained. This method is also less problematic if any issues arise with the window itself. We obviously would love to say that we never see any fault with our products, but anyone living in the real world is well aware than even the best quality item in any industry can fail at some stage! If the window were to have the render applied directly onto the face, and a window needed to be removed, that would also mean needing to break-away that brand new render in order to extract…

Class 4 airtightness Bifold installed with Polyeurathane Weather Sealing foam tape

Image from our Warwickshire Modern Scandinavian Family Home gallery

Expanding Foam Air Seal

Behind the expanding tape sits a thick layer of expanding foam. This is very much a less-is-more product, and anyone’s first attempt at using it will have almost certainly resulted in mild panic, as the tiny amount of foam shows no sign of slowing down as it expands out of the gap, all over the window and onto the floor… (Quick tip: if that happens, just start wiping it off the second you see it happening and clean any surface it has touched immediately. Ignore anyone who suggests waiting for it to dry/set first, especially if it ends up on a nearby carpet.)

Sprayed in before the compriband is installed, expanding foam forms the primary air-seal for all of our installations. Since this material is also flexible and pliable for a very long time, the foam is also able to withstand the regular small building movements without cracking.

The End Result

By using Enlightened Windows as the surveyor, supplier and installer, we aim to provide you with a well thought-out process from start to finish. You’ll be left with a Class 4 Airtight product and a Class 4 Airtight installation. All waste materials are taken away to be either recycled or re-purposed, and our thorough post-installation checks should ensure a stress-free and trouble-free customer experience. We’re very proud of our Google reviews, which all reflect the level of overall service that we always aim to provide.