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Appendix H describes the requirements for ties where the surface of the building to which the scaffold is to be tied is permeable. This is the case where an independent or putlog scaffold is attached to a frame or to a facade with a large percentage of openings:
- Unclad scaffolds may require heavier-duty ties, or additional ties
- Clad scaffolds will fail the Basic Scaffold check and must be designed
In the latest version of SMART Scaffolder users can specify whether the scaffold is tied to a permeable or impermeable facade. If the scaffold is tied to a permeable facade and is clad then a warning will be given that design advice should be sought to determine the tie requirements. If the scaffold is tied to a permeable facade and is unclad then:
- The site wind factor is required to check whether extra ties are needed. If the wind factor has not been calculated then a warning will be displayed to say that extra ties might be required.
- The additional tie calculations in Appendix H only apply to basic scaffolds. If the scaffold has failed the basic scaffold check, or if a check IT licence is not available, then a warning will be displayed to say that the requirement for extra ties can only be determined if the basic scaffold check passes.
- If the scaffold is a basic scaffold then the requirement for extra ties is calculated. This will have three effects:
1) The number of Estimated Ties may be affected
2) The number of extra ties required to account for the permeable surface will be displayed in the 'Why' breakdown screen
3) A warning message will be displayed on the tie calculator screen if extra ties are required
The sparse tie patterns (c) and (f) are not applicable to impermeable facades. If either of these patterns is selected then the Basic Scaffold check will fail.
Download your FREE copy of the TG20:08 Appendix H pdf HERE
(links to the NASC Web site)
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