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Long time ago, we worked out that most homeowners who wanted really pretty looking windows didn’t want shiny plastic, mitre welded ones.We knew wood foil, with traditional butt joints was the answer, however there was a problem, most mechanical joints are open ended, meaning water easily penetrates. What was needed was a new method of joining the sections together to provide a fully sealed waterproof joint, which gave the impression that the joint was a traditional “butted” appearance.

Ray Rabett our Technical Director came up with a clever solution which was patented in 2005.

This new and novel method which was another first for Masterframe meant we have led the sash window field with an authentic, vertical butt jointing method ever since.

Now it seems that casement manufacturers are finally catching up. Flush sash or flush casements are the latest style that fabricators are making. Many are only now recognising that standard mitred joints simply accentuate the plasticy look.

Millions are being invested by fabricators buying new Graff welders, believing these are the only machines capable of providing a neat solution. However TMS now have in association with Masterframe found far cheaper solutions, welding butt mitred joints.

Although it has taken 10 years for the casement manufacturers to catch up with the idea, many are now finding that sales of their new flush casement depend upon them obtaining permission and a license for our patent.

First to get approved is fellow VEKA fabricator and long time customer of Masterframe, Michael Hagan of Aztec Windows (Coventry) Ltd.

Aspiring to make their range of Prestige casement windows to match the beautiful butt jointed appearance of the sash windows they purchase from Masterframe, Michael, was delighted to be able to legally launch his flush casement window at the FIT Show earlier this year and was so glad he did, as it has excellent potential.


He said, “Having looked at other construction methods, it was clear Masterframe’s method was really neatly finished sturdy and more reliable than any of the other methods they considered. We are really pleased to be able to offer our customers the best looking and performing corner joint on the market!” He went on to say, “Initially, like so many other fabricators, we were blissfully unaware that a patent existed, but now we have the agreement, we can use it to prove our customers won’t get sued!”

Butt joint licences issued

Masterframe are in negotiations with a number of interested parties as welding butt joints becomes ever more popular.

Our MD Alan Burgess says,”Butting” joints look fantastic but as with so many things in life, doing it “on the cheap”, (like a competitors sample above right) simply means air and water will pour through any gaps. Doing it right is time consuming. Retail purchasers of sash windows want really neat aesthetics. On the whole we have little objection to issuing licenses to fellow fabricators, just so long as they aren’t making sash windows!”

If you are thinking about making windows using this jointing method, welded or mechanical, you’ll need permission and a license. Anyone interested in avoiding a legal wrangle should contact us direct.