--- url: https://qsteelcad.com/en/blog/strap-tension-and-tensioners language: en alternate: https://qsteelcad.com/blog/serit-gerginligi-ve-gerdirici updated: 2026-11-06 publisher: RENMAE Teknoloji ve Yazılım LTD. ŞTİ. --- # Strap tension and tensioners: why does slack bracing cause problems? The regulation says it in one sentence: strap bracing connections are made taut. A slack strap engages late once load arrives, and the wall moves more than expected. How is tension achieved, and when is it checked? ## Short answer A slack strap takes up its slack first under load; the panel moves meanwhile and the brace engages late. Turkish Building Earthquake Code 2018 (TBDY 2018) 10.4.3(b) requires strap bracing connections to be made taut, with the panel plumb and in position. There is no universal tensioning force or torque value; system instructions and project detail govern. ## Key points - A slack strap lets the panel move before it takes any load. - TBDY 2018 requires strap connections to be made taut (10.4.3b). - The strap is fixed with the panel plumb and in its correct position. - Dead loads added later can change the strap tension. - A photo does not give you a torque, a tensioning force or a capacity. Strap bracing is a thin steel band and behaves like a rope: if it is taut it takes load immediately, and if it is slack it first takes up the slack. On paper the difference looks small, but it governs the lateral stiffness of the panel. TBDY 2018 10.4.3(b) reduces this to one sentence: the connections of strap braces shall be made taut. ## What does a slack strap lead to? When a lateral force arrives, the panel starts to rack sideways. If the strap is slack, it carries no force during that movement. It only starts to take load once the slack is gone. By then the panel has moved more than expected. Sheathing, frames and connections all see this extra movement. ![Two panels: on the left a sagging slack strap and extra displacement under load, on the right a taut strap with the diagonal taking load immediately](https://qsteelcad.com/assets/img/blog/gevseklik-en.webp) In an earthquake the problem repeats. A strap that has stretched in tension may not return fully to its original length when the load is removed. In the next cycle the slack is larger, and the panel moves again while taking it up. So the initial tension of the strap is not only a matter of appearance. ## Why does a strap go slack? - The strap was fixed before the panel was brought plumb. - The strap was screwed off without being pulled by hand while connecting. - The strap slipped while the screws were being tightened in sequence. - The panel changed shape during transport or lifting. - Sheathing and finishes added later settled the structure downward. - The strap was left on a long span without being connected to intermediate studs. ## When is tension checked? A single moment is not enough. The first check is made while the strap is being connected, with the panel in the correct position. The critical check comes after most of the dead load has been applied to the structure. A large part of the building's weight comes from finishes, and these are mostly added after the structural system has been inspected. That is why a last check before the sheathing is closed is valuable. | Stage | What is checked | | --- | --- | | While assembling the panel in the factory | Was the strap connected with the panel square? | | After the panel is erected | Is the panel plumb, is the strap sagging? | | When the storey is complete | Is the strap still taut after the upper loads have arrived? | | Before the sheathing is closed | Final visual check; if needed, correct according to the system instructions. | ## What is a tensioner? A tensioner is an erection component used to fix the strap under tension. Systems do not all solve this the same way: in some details the strap is pulled over a part and fixed, in others a separate product is used, and in some systems the tension comes from the erection method. A photo of a product fitted to a strap does not show that it suits every strap and every framing type. The product family, material, connection method and the manufacturer's instructions are checked together. An application pulled tight on timber framing is not evidence for a steel connection. Make sure the strap and the tensioner are specified for the same system. ## How much should the strap be tensioned? There is no single numerical answer to this question. The required tension depends on the strap section, the panel length and the chosen system. Over-tensioning is also a problem: the panel can be pulled out of plumb, or an unaccounted force can develop in the chord studs. So the adjustment is made together with a plumb and alignment check of the panel, following the instructions of the chosen system. > This article deliberately gives no torque or tensioning force value. These values come from the system instructions and the project detail; they are not taken from another job or from a photo. ## Quick site checklist - Is the panel plumb and square? - Is the strap visibly sagging? - Were both diagonals connected with the same care? - Are the end screws complete and in the pattern shown in the project? - Is the strap connected to the intermediate studs as the project requires? - Has the strap been cut or bent for another task? - Were the inspection date and the panel ID written on the form? Read next: [Light steel fabrication and erection checklist: how to use Table 10.1](https://qsteelcad.com/en/blog/fabrication-and-erection-checklist) ## How does production help here? The precondition for tension is correct geometry and a square panel. If parts are produced at the right length and with the right hole positions in the factory, the panel sits in place on site without being forced. QSteelCAD writes the length and operation positions of every profile to the .bde file in millimetres. Strap tension itself is a job done and checked during erection; the program does not measure it. ## Frequently asked ### How taut should strap bracing be? There is no universal value. The instructions of the chosen system and the project detail govern. Tension is set together with the plumb and alignment check of the panel. ### Can a strap that has gone slack be corrected later? It is corrected by the method the system instructions allow. Cutting the strap on site and reconnecting or splicing it changes the end connection; consult the project engineer first. ### Can the strap be checked behind the sheathing? Hardly, once the sheathing is closed. The check should therefore be made before sheathing and recorded. ## Related solutions - [Production and CAM](https://qsteelcad.com/en/solutions/production-and-cam)