Who this guide is for
- Homeowners hiring a plumber for repairs or upgrades
- People planning fixture changes who want compatible parts
- Anyone concerned about water shut-off and testing
- Owners comparing more than one plumber
Ask about isolation and shut-off
Before work begins, water needs to be isolated. Ask how the plumber isolates supply to the area, where the shut-offs are, and what happens if an isolation valve is seized or missing.
Knowing the isolation plan helps you understand how the rest of the home is affected during the work.
- How will you isolate supply to the work area?
- Where are the shut-offs, and are they working?
- Will the rest of the home keep water during the job?
- What happens if a valve is seized?
Ask about testing and verification
Good plumbing work is tested before it is closed up. Ask how the plumber checks for leaks and confirms the work performs as intended before finishing.
Ask how they handle anything that needs to be hidden behind walls or under floors, so it is verified before it is covered.
Ask about fixture and part compatibility
Fixtures and fittings must match your supply and drainage. Ask how the plumber confirms that chosen taps, valves and fittings are compatible before fitting them.
If you are supplying parts yourself, ask what they need and when, and how mismatches are handled.
Ask about access, protection and clean-up
Plumbing work can mean lifting floors or opening walls. Ask how access is gained, how surrounding finishes are protected, and how the area is left after the work.
Ask how debris and old fixtures are removed and how the site is cleaned at the end.
Ask how problems and sign-off are handled
Ask what happens if a hidden issue appears once pipework is exposed, how changes are agreed, and how the work is checked before sign-off.
For any gas work, confirm the plumber holds the relevant qualifications; Build Design Hub does not verify this, and requirements vary by location and project.
Questions checklist
- 1Ask how supply is isolated and where shut-offs are
- 2Ask whether the rest of the home keeps water during work
- 3Ask how the work is tested for leaks before finishing
- 4Ask how hidden work is verified before being covered
- 5Ask how fixtures and parts are confirmed compatible
- 6Ask how access is gained and finishes protected
- 7Ask how debris and old fixtures are removed
- 8Ask how hidden issues, changes and sign-off are handled
Common mistakes to avoid
- Not asking how water will be isolated during the job
- Skipping questions about testing before work is closed up
- Supplying parts without confirming they are compatible
- Overlooking protection of floors and finishes near the work
- Assuming a plumber is qualified for gas work without asking
- Not agreeing how hidden issues and changes are handled
When to involve a professional
- Plumbing and especially gas work belong with qualified professionals
- Ask to see relevant qualifications and insurance rather than assuming them
- Hidden pipework should be tested and verified before being covered
- Build Design Hub does not perform or verify plumbing or gas work
- Requirements vary by location and project, so confirm specifics locally
Frequently asked questions
Questions readers ask about this topic
Why ask about isolation first?
Because work cannot safely begin until the supply is isolated, and a missing or seized valve can complicate the job. Knowing the plan tells you how the rest of the home is affected.
How do I know the work was done well?
Ask how the plumber tests for leaks and verifies the work before closing it up. Anything hidden behind walls or floors should be checked before it is covered.
Can I supply my own fixtures?
Often yes, but ask the plumber to confirm compatibility with your supply and drainage first, and agree how mismatches are handled to avoid hold-ups.
What about gas work?
Gas work is safety-critical and requires specific qualifications. Ask to see the relevant credentials; Build Design Hub does not verify them, and requirements vary by location and project.
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