Sub-surface ERH readings – using Hygromaster and Humidity Sleeve
As an alternative to surface ERH readings, Hygrosticks can
be put into humidity sleeves that are placed into holes drilled
into the slab.
Whilst this technique is not incorporated in British Standards
it is widely used in the UK, Scandinavia and Continental
Europe.
The sleeve technique offers the following advantages:
•Provides a more accurate measurement on the ERH of
the concrete
•Is unobtrusive and tamper-proof (when compared with
humidity boxes)
GE Sensing recommend that you use the Hygromaster and humidity sleeves in accordance with the
guidelines of applicable standards. The quick reference guideline is as follows:
1. Check if it is suitable or desirable to drill holes in the floor; if not, use the surface humidity box test
method. The sleeve test is only suitable for solid slabs where the DPM (or under floor heating system, if
incorporated) is known to be at a depth of at least 75mm below the surface.
2. Use the Aquant to identify the areas that require measuring with the Hygromaster and humidity sleeve
3. At these points, drill a 16mm diameter clearance hole to a nominal depth of 50mm
4. Push the sleeve into the hole. Ensure that the sleeve flange is flush with the surface and ensure that the
sleeve cap is put in place.
5. Before taking measurements, leave for 24 hours minimum for equilibrium conditions to be reached.
6. Remove the humidity sleeve cap and insert the Hygrostick. When pushed firmly into place, the conical
sleeve fitted to the Hygrostick makes a seal with the humidity sleeve.
7. Leave the Hygrostick in place for minimum of 30 minutes, to allow it to acclimatise with the conditions
within the humidity sleeve.
8. Connect the Hygromaster to the Hygrostick using the extension lead as shown and take the humidity
measurement.
9. Check readings at 5-minute intervals. It is safe to assume the probe has acclimatised when 3
concurrent readings are within ± 0.3%rh of each other.
Interpretation of readings: generally speaking, readings of less than or equal to 80%rh are considered dry. If
there is any doubt or ambiguity regarding the slab moisture level, consult with the manufacturers of the
specified adhesives and/or decorative floor coverings before laying.
Relevant Flooring Industry Standards
The Hygromaster and humidity box can be used to measure moisture levels in accordance with the
requirements of the following standards:
British Standards
BS 8203 – Code of practice for installation of resilient floor coverings
BS 8201 – Code of Practice for flooring of timber, timber products and wood based panel products
BS 5325 - Code of practice for installation of textile floor coverings