TG20:13 Guide to Good Practice for Tube and Fitting Scaffolding was launched in February 2014, and replaced the previous guidance, TG20:08. TG20:13 was made up of four elements as detailed below.

The next version of TG20 is now launched. Further information about TG20:21 can be found here.

TG20:13 users can register to use TG20:21 here using their existing TG20:13 serial number. Use of TG20:21 was free of charge for three months from the date of launch (12th April 2021), for all users, and for longer for users who purchased in 2019, 2020 or 2021.

With the introduction of TG20:21, there was a ‘transition period’ to give the industry adequate time to adjust to the new requirements, in a planned and controlled way. Existing scaffolds constructed in compliance with TG20:13 and associated compliance sheets remained acceptable and did not require modification. TG20:13 compliance sheets were still valid and could continue to be used for the construction of new scaffolds for a few months.  TG20:13 was formally withdrawn, in favour of fully adopting TG20:21 on the 12th October 2021. Further information can be found here. 

Four elements of TG20:13

1. TG20:13 Operational Guide A full-colour, 224 page guide containing detailed practical guidance for most common types of scaffolding supported by structural research and calculations. Guidance was provided for an expanded range of structures which included independent scaffolding, interior birdcages, chimney stack scaffolds, loading bays, ladder-access towers, free-standing towers, lift shaft towers and putlog scaffolding.

2. TG20:13 Design Guide Intended predominantly for engineers and designers, this 206 page document provided technical data, commentary, and source material for use by competent and suitably qualified scaffold designers in circumstances which were outside the scope of standard solutions provided in the TG20:13 Operational Guide and TG20:13 e-Guide software.

3. TG20:13 e-Guide Designed for Mac, PC and tablet use, making it extremely easy to check scaffolds for TG20:13 compliance digitally, with user-friendly software which will facilitate printing and circulation of details of TG20:13 compliant structures by email.

4. TG20:13 User Guide A 32 page full colour pocket guide in A6 format, this document clearly summarised the requirements for compliant TG20:13 scaffolding and offered indispensable guidance to the scaffolding operative.

While you continue to use TG20:13, please see below for help in solving problems with your installation, or for software downloads to allow you to move your installation to a new machine.

Downloads for TG20:13 version 1.3

TG20:13 eGuide 1.3 update for Windows

TG20:13 eGuide 1.3 update for MacOS– please contact CADS support using the contact details below

TG20:13 eGuide 1.3 update for Android devices

Installation Problems

If you receive an error message saying “The application cannot be installed due to a certificate problem.  The certificate does not match the installed application certificate, does not support application upgrades, or is invalid.  Please contact the application author.”  As it is not possible to directly update from a previous version of the eGuide to the new 1.3 version please make sure the previous version is uninstalled before updating to 1.3.

If you receive an error message during installation that says the TG20:13 eGuide file is damaged, it may be that the anti-virus software on your computer (such as Norton or McAfee) has blocked part of the installation.

To resolve this problem, try temporarily disabling your anti-virus software and re-installing the eGuide.

TG20:13 FAQs

What is the NASC TG20:13 eGuide?
The purpose of the TG20:13 eGuide is to browse for TG20 compliance sheets: definitions of standard scaffolds that have been designed by structural calculation to BS EN 12811 and do not require additional design.

TG20 compliance sheets specify the design criteria for scaffolding including the height to which it may be safely erected, the maximum dimensions to which it must conform, the leg loads its foundations must support and, where applicable, the ties required to stabilise it.

TG20 compliance sheets can be exported to the Adobe PDF electronic format for printing, saving onto a computer or distribution by email.

Which computers and devices can it be used with?
The TG20:13 eGuide may be used on any PC desktop computer, laptop computer or tablet running Microsoft Windows 10, 8, or 7, or on an Apple iMac desktop or laptop computer running MacOS X version 10.9 and above.

Note that tablet computers running the Microsoft Windows RT operating system are not supported by the TG20:13 eGuide, but tablets running Windows 10, 8 or 7 are. A version of the eGuide for Android tablets is also available.

How do I install the eGuide onto my computer?
The TG20:13 eGuide must be installed onto a computer before use – it cannot be used directly from a CD.

The TG20:13 eGuide must be downloaded from the link above. Disk copies are no longer issued and previously issued disk versions are now out of date.

You may find you need to download adobe air but please only do this if you experience problems that cannot be fixed by following the Troubleshooting section below.

How do I activate the eGuide with my unique serial number?
The TG20:13 eGuide must be activated before it can be used. Every purchaser of the TG20:13 eGuide is provided with a unique serial number, which entitles you to use the eGuide on one compatible computer or device.

You will be prompted to enter your serial number when you first use the TG20:13 eGuide. You will also need to enter your company name, which should be entered exactly as you wish it to appear on the TG20 compliance sheets printed from the software.

Once the serial number has been entered the eGuide must be activated to ensure that every serial number is only used on one compatible computer or device at a time. The computer or device must be connected to the Internet to activate the TG20:13 eGuide.

When prompted, the ‘Activate now’ option should be selected to register the serial number over the Internet. If the serial number is not already in use, the TG20:13 eGuide will become activated.

If an Internet connection is unavailable, the ‘Activate later’ option can be selected, but the eGuide will run in a limited demonstration mode until it is subsequently activated. While in the demonstration mode it will not be possible to view or print TG20 compliance sheets from the eGuide.

How do I transfer the eGuide to another computer?
The TG20:13 eGuide may be transferred to another computer or device by first deactivating it. This is achieved by selecting the information button (the letter ‘i’) from the menu bar of the Welcome screen.

Then select the ‘click here’ option to deactivate, for which a connection to the Internet is required. The serial number may then be used to activate the TG20:13 eGuide on another computer or device.

How can I email or print a TG20 compliance sheet from the eGuide?
Once a TG20 compliance sheet has been selected using the eGuide, it can be exported to the Adobe PDF electronic format so that it may be printed, saved to the computer or sent by email. This is achieved by selecting the ‘Save as PDF’ option.

The free Adobe Reader software is required to view files in PDF format. It can be downloaded for PC and iMac computers from:


The TG20:13 eGuide fails to activate over the internet.
If the TG20:13 fails to activate over the Internet, and your Internet connection is working, it could be the case that personal firewall software such as Norton or McAfee is blocking the connection.

In most circumstances the firewall software will ask your permission to allow the eGuide to access the Internet: it is important that you allow this in order for the online activation to work.

In some cases, if your firewall software is configured to block Internet connections automatically without asking, you may have to add the TG20:13 eGuide to the list of trusted programs in your firewall software. To do so, please follow these instructions:



Please note that the instructions may differ depending on the version of the firewall program that you have. When you are asked to browse for the eGuide to add it to the safe list (in step 6 of the McAfee instructions) choose: C:\Program Files (x86)\NASC\TG20 eGuide

The TG20:13 eGuide installation fails because the file is damaged.
If you receive an error message during installation that says the TG20:13 eGuide file is damaged, it may be that the anti-virus software on your computer (such as Norton or McAfee) has blocked part of the installation.

To resolve this problem, try temporarily disabling your anti-virus software and re-installing the eGuide. If the problem still exists, it may be that you have insufficient Windows permissions to install the software. To solve this, right-click on setup.exe and choose Run as Administrator.

The NASC is working with anti-virus software publishers to prevent this problem from occuring, but occasional ‘false positives’ do occur. If this problem affects you please contact with the name of your anti-virus software so we can report this problem to the anti-virus software publisher.

The TG20:13 eGuide fails to activate because the serial number is already in use
A TG20:13 serial number can only be used on one computer or compatible mobile device at any time. Please follow the instructions above for moving a serial number from one computer or device to another.
Note: it is important to follow the instructions for deactivating the serial number, which is not the same as uninstalling the eGuide from the computer or device. It is not necessary to uninstall the eGuide software.

Installing the TG20:13 eGuide as an I.T Administrator
If you are installing the TG20:13 eGuide as an Administrator, please log in as the intended user of the software before entering the serial number and activating it.

Help and support

If you have any problems downloading, installing or activating the TG 20 eGuide, technical support is available from CADS, the authors of the TG 20 eGuide software.

Telephone support is available from 09:30 – 17:00, Monday to Friday.
+44 (0)1202 603733

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