{"id":2992,"date":"2026-07-13T11:10:38","date_gmt":"2026-07-13T10:10:38","guid":{"rendered":"https:\/\/blog.newcomponit.com\/?p=2992"},"modified":"2026-07-13T12:24:25","modified_gmt":"2026-07-13T11:24:25","slug":"insulation-that-reduces-efficiency-what-happens-when-you-cover-a-fabric-expansion-joint-as-if-it-were-a-pipe","status":"publish","type":"post","link":"https:\/\/blog.newcomponit.com\/en\/insulation-that-reduces-efficiency-what-happens-when-you-cover-a-fabric-expansion-joint-as-if-it-were-a-pipe\/","title":{"rendered":"Insulation that reduces efficiency: what happens when you cover a fabric expansion joint as if it were a pipe"},"content":{"rendered":"\n

Have you ever come across a fabric expansion  joint<\/strong> that has deteriorated earlier than expected, for no apparent reason? In most cases, the answer does not lie in the quality of the expansion joint itself. It lies in what has been placed on top of it<\/strong>.

When a component designed to move and dissipate heat is treated as a fixed pipe<\/strong>, wear and tear accelerates and the problem only becomes apparent months later, during maintenance, by which time the damage has already been done. Understanding why this happens is the first step towards preventing it from happening again.<\/p>\n\n\n\n

<\/div>\n\n\n\n

A fabric expansion joint is not a pipe: treating it as such has a cost<\/h2>\n\n\n\n

A pipe is static. You cover it, insulate it, fit a metal sheet over it and leave it alone for years. A fabric expansion  joint works in a completely different way<\/strong>: it absorbs the thermal expansion of the duct and dampens vibrations, which means it has to move with every thermal cycle and every change in pressure.<\/p>\n\n\n\n

If you encase it in a rigid cover<\/strong>, you are working against its natural function. The fabric continues to move \u2013 it cannot do otherwise \u2013 but it does so against a constraint that was not intended. Over time, that constraint becomes the main cause of premature deterioration<\/strong>. It is not a question of the quality of the material, but of how it was installed.<\/p>\n\n\n\n

<\/div>\n\n\n\n

When heat cannot escape, it builds up where it shouldn\u2019t<\/h2>\n\n\n\n

There is a second effect, less visible but just as significant. The fabric expansion joint is designed to release heat to the outside<\/strong>, so when you cover it with a tightly-fitting metal sheet, that heat becomes trapped between the fabric and the covering.<\/p>\n\n\n\n

In technical terms, this is known as \u2018heat trapping\u2019.<\/strong> Internal temperatures rise above design specifications, the fabric operates under more severe conditions than anticipated and its service life is consequently reduced. From the outside, nothing appears amiss. But the process is already underway, silently, with every cycle.<\/p>\n\n\n\n

<\/div>\n\n\n\n

Two solutions that protect without stopping the movement<\/h2>\n\n\n\n

If you want to reduce heat loss<\/strong> along the duct without damaging the expansion joints<\/strong>, there are two approaches that that can solve the problem at its root<\/p>\n\n\n\n