A duct joint that leaks does not announce itself. The system still blows air, the commissioning sheet still gets signed, and the loss only shows up months later as a higher electricity bill and a room that never quite reaches setpoint. Most of those leaks are not a product failure — they are an application failure.<\/p>\n
This is the sequence our technical team recommends when sealing joints and seams with Q Tape aluminium tapes, and the mistakes we see most often on site.<\/p>\n
Pressure-sensitive adhesive bonds by flowing into the surface it touches. It cannot flow into dust, sand, oil or water. On a Saudi site the first three are guaranteed to be present.<\/p>\n
Q Tape aluminium tapes have a tested application temperature range of −12 °C to 120 °C<\/strong>. That is the temperature of the surface<\/em>, not the air. A duct sitting in direct sun on a rooftop in July can be far hotter than the ambient reading, and a chilled duct that has already been commissioned can be well below it.<\/p>\n If the surface is out of range, wait or shade it. A tape applied outside its range may hold for the walk-around inspection and release later, because the adhesive never wetted the surface properly.<\/p>\n Cut each piece to the length you need, with enough to overlap. Pulling tape off the roll under tension and stretching it into place builds a permanent stress into the joint; the tape will try to return to its original length and will pull at its own edges for the rest of its life. This matters more with foil tape, which elongates 5%, than with FSK, which elongates only 2%.<\/p>\n Centre the tape over the joint so that an equal width bonds to each side. On a longitudinal seam or a transverse joint, aim for a minimum overlap of 25 mm onto sound facing on each side. Where two lengths of tape meet, overlap them by at least 50 mm and lap them in the direction that sheds water, exactly as you would with a roofing detail.<\/p>\n Pressure-sensitive means exactly that: the bond is created by pressure, not by time. Run a plastic squeegee or a gloved thumb firmly along the full length of the tape, working from the centre outwards to push out trapped air. Pay particular attention to the two edges, since that is where failure always begins.<\/p>\n Done properly, the foil takes on the texture of the surface underneath. If the tape still looks like a flat strip sitting on top of the joint, it has not been pressed down.<\/p>\n Straight runs on faced insulation are FSK work. Elbows, take-offs, damper frames and irregular fittings are foil tape work — it stretches into shape instead of tenting. Trying to force a reinforced FSK tape around a tight radius leaves bridged edges that will never bond, and a bridged edge is an open joint.<\/p>\n Before the insulation is covered or the ceiling is closed, walk the run and look for four things:<\/p>\n Anything you find now costs a minute to fix. The same defect after commissioning costs a scaffold and a ceiling.<\/p>\n3. Cut to length, do not tear and stretch<\/h2>\n
4. Centre the tape and overlap correctly<\/h2>\n
5. Apply firm pressure — this is the step that gets skipped<\/h2>\n
6. Detail the awkward parts with the right product<\/h2>\n
7. Inspect what you sealed<\/h2>\n
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Common mistakes worth naming<\/h2>\n