# ASTM D4263

Source: https://coatmentor.com/standards/astm-d4263/ · Updated 2026-10-14

Moisture in concrete shown by a taped plastic sheet.

**Publisher**: ASTM International

**Area**: Concrete

ASTM D4263 is the simple qualitative check for moisture in concrete before coating. The 2024 edition renamed it a standard practice.

## The procedure

Tape a clear polyethylene sheet, about 0.1 mm (4 mil) thick and 18 × 18 in., tightly to the concrete on all four edges. Leave it for at least 16 hours under the conditions in which the coating will be applied. Then lift it and look at the underside of the sheet and the concrete for condensation, dampness or darkening.

## Points to remember

- The result is yes or no: moisture seen or not seen. It gives no rate and no percentage.
- Keep sunlight and heaters off the sheet: they upset the result.
- It also applies to walls and ceilings, not only floors.

## When a number is needed

A dry sheet says only that no moisture showed under it in that time. For a rate, ASTM F1869 (the calcium chloride test) measures the vapour emission of a bare floor, though critics note that it reflects mainly the top layer of the slab. In-situ relative humidity probes in drilled holes (ASTM F2170) measure within the slab.

**2** practice items in the members area mention ASTM D4263 (CIP 2: 1 · FROSIO written: 1).

## Related

- **Concepts:** [Drying, curing and recoat windows](https://coatmentor.com/learn/cure-and-recoat/)
- **Standards:** [ASTM F1869](https://coatmentor.com/standards/astm-f1869/) · [ASTM F2170](https://coatmentor.com/standards/astm-f2170/)
- **Defects:** [Efflorescence](https://coatmentor.com/defects/efflorescence/)

## About this page

This page describes the subject of ASTM D4263 in our own words; it does not reproduce the standard. For the full text, buy the current edition from ASTM International. Checked on 2026-10-14; errors go in the [corrections log](https://coatmentor.com/method/). CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.