01
Edition 3 withdrawn
Edition 3 was withdrawn on 30 September 2026. Edition 4 applies to every test from 1 October 2026.
Live from 1 October 2026
Understand and test the new IGEM/UP/1B Edition 4.
Same tightness test, new way to judge it. Watch the 5 minute guide, then let the Tightness Test app work out the volume, allowed drop, purge and the record for you.
For Gas Safe registered engineers and apprentices.
Video coming soon.
What changed
The test is the same. How you judge it is new.
02
Drop set by installation volume
The allowed drop now depends on the installation volume (pipework, fittings and meter), not the meter size.
03
Retest the pipework alone
Appliances connected and a small drop? Isolate them and retest the pipework on its own.
The Tightness Test app
The maths done for you, on site.
Installation volume
Enter pipe lengths and the meter; fittings at 10% or actual.
Allowed drop
The right band for the volume, shown the moment you enter it.
Purge volume and method
1.5 × IV, rounded up, and whether to purge to air or to ignition.
The test record
Let-by, test, leak detection fluid check and result, ready to print or share.
Three steps on every job.
1. Enter the installation
Gas type, meter and pipe lengths.
2. Do the test
Let-by, stabilise, 2 minute test. Enter the readings.
3. Share the record
PASS or FAIL against Edition 4, as a PDF.
Free for 30 days.
Download the Tightness Test app and do your next test to Edition 4.
Coming soon on the App Store and Google Play.
FAQ
Who is it for?
Gas Safe registered engineers and gas apprentices testing installations covered by IGEM/UP/1B.
What installations does UP/1B cover?
Up to 0.035 m³ installation volume, pipe up to 35 mm and a meter up to 16 m³/h. Above that, IGEM/UP/1A applies.
Does it replace my judgement?
No. It is an aid. The engineer remains responsible for testing to the current IGEM/UP/1B.
Terms of use and privacy
For the Tightness Test app. Last updated 4 October 2026.
What this app is
Tightness Test helps a Gas Safe registered engineer carry out and record a gas tightness test following IGEM/UP/1B Edition 4. It does the sums and keeps a record.
You stay in charge
The engineer carrying out the work is responsible for testing safely and to the standard, for reading the gauge correctly and for the decision to pass or fail an installation. The app is an aid and is not a substitute for training, the standard itself, the Gas Safe Register's guidance or the manufacturers' instructions. Always check the figures against the current standard.
Free month and price
Every new account has a free 30 day trial. After that the price is £3 a month unless we tell you otherwise. You can stop at any time. Your saved tests and PDFs stay available to you after the trial ends.
Your records
Records belong to you. Keep copies of the PDFs you issue.
Fair use
Do not share your login, and do not use the app to record a test that was not carried out.
Our responsibility
We take care to keep the app accurate and available, but we cannot promise it will always be free of errors or interruptions. To the extent the law allows, we are not responsible for losses that come from relying on a result without checking it, and nothing here limits liability that cannot be limited by law.
Changes
We may improve the app and update these terms. We will tell you about important changes.
Privacy: who we are
Tightness Test is made by Flueprint (flueprint.app). If you have a question about your data, email hi@flueprint.app.
Privacy: what we keep
- Your email address and the name you sign in with (email and password, or your Google account).
- The profile you give us: your name, business name, Gas Safe number and phone number. The ones marked optional are optional.
- The tests you save: the job address, customer name, post code, the readings you enter and the result.
- When you joined, which wording you agreed to, and that you agreed to these terms.
- If you already use Flueprint with the same login, we fill in your name, business, Gas Safe number and phone from there. You can change them.
Privacy: what we use it for
- To run the app, keep your tests safe and show them to you on any device you log in on.
- To print your name, business and Gas Safe number on your records.
- To manage your free month and your subscription.
- To email you about your account and the app: updates, changes to these terms, your trial and your subscription. These are part of the service.
- To show you news about Flueprint and our other apps inside this app.
Privacy: who sees it
Only you, and Flueprint's staff where we need to run the service or answer a question. Your data is stored with Google Firebase (Google Cloud) and is encrypted in transit and at rest. We do not sell your data and we do not share your tests with anyone.
Privacy: how long we keep it
We keep your email address and details for as long as you have an account. If you delete your account in the app, your tests, profile and login are deleted straight away. You can also ask us at hi@flueprint.app to delete them.
Privacy: your rights
You can see, correct, export and delete your data. Use Account in the app, or email hi@flueprint.app. You can also complain to the Information Commissioner's Office (ico.org.uk).
Same login as Flueprint
Your login also works in Flueprint. Your tests stay private to you.