A new extension is finished in March and the floor goes down in April. The screed looked dry, felt dry and had been down for six weeks.
By September the boards have cupped across the whole room and the adhesive has failed in patches. The screed was still releasing moisture, nobody measured it, and the floor is a total loss.
1. Understand why it fails months later
Moisture in a subfloor rises until it meets an impermeable covering, then spreads sideways. Nothing visible happens for weeks, which is exactly why people skip the test.
2. Test rather than judge by feel
A surface can feel completely dry over a slab holding a great deal of moisture. Touch tells you about the top few millimetres and nothing about the rest.
3. Use a method appropriate to the subfloor
Concrete, screed, timber and existing coverings all need different approaches, and a reading from the wrong method is worse than no reading.
4. Take readings in several places
Perimeter, centre, near any external wall and anywhere the slab is thicker. A single central reading misses the areas most likely to be wet.
5. Allow the test the time it needs
Meaningful methods require the equipment to be in place for a period. Customers push to skip this and it is the part that cannot be shortened.
6. Know the drying reality on new builds
New concrete and screed take a long time, and the figures surprise everybody. A programme that assumes a few weeks is a programme that will fail.
7. Ask what heating has been running
An unheated building dries slowly, and force drying with the wrong approach causes its own problems. What has happened matters as much as the elapsed time.
8. Check for a damp proof membrane
Older properties may have none, a failed one, or one nobody can confirm. This changes the specification entirely.
9. Look for the other sources
Leaking pipework under a floor, a failed seal in an adjoining wet room, or ground levels outside. A high reading in one corner is a clue rather than a verdict.
10. Explain the surface treatment options
Moisture suppressant systems exist and work where correctly specified. They cost money and they are far cheaper than a failed floor.
11. Be clear about the guarantee position
Most manufacturers void a warranty where moisture limits were exceeded. Fitting anyway transfers the entire risk to whoever laid it.
12. Put the test result in writing
A recorded reading with a date protects everybody, and it is the document that settles any later argument.
13. Handle the customer pressure honestly
A customer with a deadline will ask you to proceed. Declining in writing is the professional answer and it is not a lost job, it is a delayed one.
14. Connect it to the wider preparation
Levelling, cleaning and priming follow from the same assessment, as covered in subfloor preparation questions that change quotes.
15. Account for the heating interaction
Underfloor heating requires its own commissioning sequence before testing means anything, which is the constraint in underfloor heating compatibility questions.
16. Ask the right questions at enquiry
An assistant that asks the property age, whether it is a new build or extension, when any screed was laid, whether the heating has been on and whether there is any history of damp identifies the jobs that need testing before anybody quotes. Refining those questions from real enquiries is what testing an assistant with real past enquiries describes, and the same level checking logic appears in level test and course questions from language learners. See features, start at try, and the sector view sits under contractors.