Flooring Technical Guides
Subfloor Moisture Checks Before Flooring
A surface-water claim and a substrate moisture assessment answer different questions.
Separate the covering from the base
A flooring surface may be sold with a water-resistance claim, but the substrate and fixing system still have their own conditions. Ask what exposure the product claim covers and how moisture below the covering will be assessed. A sales description cannot establish the condition of a concrete slab, screed or existing finish.
Record known leaks, damp patches, previous damage and the site history. These observations help form an assessment brief; they are not a numerical test result or a diagnosis of the moisture source.
Use the product system’s acceptance criteria
Obtain the installation guidance for the exact floor, backing and adhesive. Manufacturers may specify assessment methods and limits for their systems. Do not apply one online number to every vinyl plank, carpet backing, adhesive and substrate.
Interface publishes installation guidance for its carpet systems, and Quick-Step provides instructions for its vinyl collections. These are examples of where to obtain system requirements. The installer must use the relevant local product and accessory documents for your project.
Ask for a recorded assessment
| Record | Question to ask |
|---|---|
| Location and substrate | Which areas and substrate layers were assessed? |
| Method | Which assessment or test method was used and why? |
| Conditions | What relevant site conditions and timing were recorded? |
| Result | What was measured or observed, with the units where applicable? |
| Acceptance criteria | Which product or adhesive requirement was used? |
| Action | What further investigation, drying or preparation is proposed? |
Resolve a source, not just the symptom
Where a leak or persistent damp condition is suspected, identify the appropriate person to investigate before the floor is covered. A different covering does not repair a pipe, waterproofing issue or another underlying cause. Ask who is responsible for the investigation and what evidence is needed before installation proceeds.
A treatment or moisture-control system, if proposed, should be named and supported for the actual substrate and flooring arrangement. Avoid accepting “moisture proofing included” without the system, scope and conditions.
Coordinate the installation programme
Preparation and readiness checks can affect the start date. Clarify when the substrate will be assessed, how findings are reported and who approves additional work. If removal is needed to reveal the base, separate the initial quotation from the process for confirming the final preparation scope.
Record the go-ahead for installation with the relevant documentation. This does not promise that future leaks cannot occur; it establishes how the starting conditions were assessed.
Keep the evidence at handover
- Assessment method, locations and recorded results.
- Product and fixing-system requirements used.
- Details of agreed preparation or moisture-control work.
- Any unresolved conditions and responsibility for them.
- Care, warranty and repair contact information.
For wood, changing moisture conditions during use are also relevant. Read the wood guide and keep the manufacturer’s environmental guidance.
Sources and further reading
Consult the current instructions for the exact product and project. Manufacturer examples explain their own systems; they do not certify every material sold in Singapore.
Continue with a specialist guide
Use these guides to resolve the next questions in your project brief.
Independent editorial guidance. Check the current documents for the exact product and project.
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