We’ve spent a lot of time, money and research to make our modern-day double glazing highly energy efficient. Some very highly specified windows achieve a WER of A++20 and above on the disputed WER scale. U-Value are getting lower and lower. If our industry keeps its foot on the gas, who knows how efficient our windows could become.

Yet, we have ignored one very obvious area of window and door installation that is vital to the overall energy efficiency of every single project, and that is how we fix windows and doors to a wall. Right now, we use silicone. With arguably better alternatives out there, is it time to ditch silicone in favour of something else?

Outdated installation method

I would hazard a guess that the vast majority of installers still use silicone when sealing windows and doors. We’ve been using silicone for decades. In the ’80s, when window technology was vastly inferior to what it is now, silicone seals were perfectly fine.

But it’s 2016. Window technology is far more advanced now. Yet, we’re still using silicone to seal around windows and doors. The problem with this is that silicone as a material is a very poor insulator. I was once told that the U-Value of silicone is around 2.6, perhaps even worse.

So whilst we’re taking pride in fitting such advanced windows and doors, we’re actually ignoring aperture sealing, preferring to use silicone. So instead of the window or door opening is completely sealed properly, we’re letting heat manage to find its way out around the very edges of the windows and doors and then leak out through the silicone. You could put expanding foam around the edge if there is a gap large enough, but foam isn’t often used, and that’s not much better anyway.

Not everyone is using this outdated installation method. Some installers have made the switch to a dedicated expanding tape.

Time to ditch the silicone?

I am seeing an increasing number of installers make the switch from silicone to these expanding tape sealing solutions. There are a couple out there that are well known. There is Tru-Fit, from the people at Edgetech. There is also Iso-Chemie and their wide range of expanding sealant tapes.

These products are very simple, which is what makes them such a good idea. They are tapes that are packed very thin on the roll. But once a length is rolled out, fitted to the edge of the window and the top protection removed, this tape then gradually expands. Installers fit the window and then watch as the tape expands to many times its original width to butt tightly up against the wall. Take a look at a video from Iso-Chemie on how it works:

Simple. Roll out the tape, cut to size, fit the window and the tape does the rest of the work as it expands to fill the gaps. Not only is the window opening now a ton more insulated and efficient, but it also looks slick too. Brick walls are easy enough to seal up against, but when it comes to working with stone, it’s not always straightforward. But with expanding tapes like these, there’s no need for scribed trims or messy silicone lines. Just fit the tape, fit the window and then step back to admire your work.

They come in different colours, different widths and different depths. It would be a case of buying the right one for each job. So is it time that installers started to ditch silicone on mass? The evidence would suggest so.

Installers would save a fortune on silicone! Bigger installers will get through many boxes of the stuff per week. It’s messy, and if it’s particularly cold outside, if the temperature is low enough, you can’t use it anyway. These tapes are a much more efficient method of insulating the window and door opening, without the mess. The costs are reasonable. They look good against any masonry. Also, for the installer, it’s an all-important extra USP.

If all around you your competition continues to use cold, messy, expensive silicone, your use of these tapes gives you an extra advantage when it comes to explaining how your products are installed. And these tapes do work. If you go on to either of the two websites linked above, you can see before and after thermal images and the difference is stark.

But will these tapes signal the end of silicones altogether? No, probably not. More thermally efficient or not, some installers will prefer to stick with what they know, and that means using silicone. They may not actually like how these tapes look. So might certain homeowners, who want a traditional seal around their windows rather than a modern tape. So whilst there is a more energy-efficient, simpler, modern way to seal a window and door, archaic attitudes will keep the silicone makers and sellers in business. Which will be music to their ears!

For me, these tapes are the future of window and door installation. It makes no sense to advertise such fantastic windows and doors, for them to then be let down by such an inefficient method of sealing. On the continent, these tapes are the norm. Silicones were ditched a long time ago. How long will it take for us to catch up?

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