Mould inspection

[edit] Introduction

Mould can develop unnoticed behind walls, beneath flooring, within roof spaces, sub-floor voids and around plumbing leaks long before visible signs become apparent. A professional mould assessment can help identify hidden moisture problems, detect mould growth and assess conditions that may affect indoor environmental quality. Whether carried out as part of routine property maintenance, following water damage, or during the purchase of a property, a mould assessment can provide valuable information about the condition of a building and the factors contributing to mould growth.

[edit] Mould growth and property inspections

Mould is a naturally occurring fungus that grows where sufficient moisture is present. Although mould spores are found naturally in both indoor and outdoor environments, excessive indoor mould growth usually indicates persistent dampness or water ingress. Because mould often develops in concealed locations, it may not be discovered until staining, musty odours or building defects become evident.

Common locations where mould may develop include:

• Bathrooms.
• Basements and cellars.
• Roof spaces.
• Sub-floor voids.
• Around windows.
• Beneath sinks.
• Behind plasterboard.
• Around heating, ventilation and air conditioning (HVAC) equipment.
• Areas affected by roof or plumbing leaks.

A mould assessment is a systematic inspection of a building to identify existing mould growth and the conditions that support it. Rather than focusing solely on visible mould, the inspection seeks to identify moisture sources, assess ventilation and determine whether building conditions are likely to promote future mould growth. Depending on the circumstances, an assessment may include:

• A visual inspection.
• Moisture meter measurements.
• Thermal imaging to identify areas of elevated moisture.
• Relative humidity measurements.
• Air sampling, where appropriate.
• Surface sampling, where justified.
• Inspection of roof spaces and sub-floor voids.
• Assessment of ventilation systems.

The objective is to identify both current mould growth and the underlying moisture problems that require remediation.

[edit] Indoor air quality and moisture

Indoor air quality can be adversely affected by persistent dampness and mould growth. As mould colonies develop they release microscopic spores into the air, which may circulate throughout a building by natural air movement or mechanical ventilation systems.

Indicators of mould-related indoor environmental problems may include:

• Persistent musty odours.
• Increased airborne particulate matter.
• Damp smells.
• Visible condensation associated with excessive moisture.
• Evidence of prolonged dampness.

Air sampling may sometimes be used as part of an investigation, although it is generally considered supplementary to a thorough building inspection and moisture assessment rather than a substitute for them.

[edit] Indicators of potential mould problems

A mould assessment may be appropriate where there is evidence of excess moisture or conditions known to encourage mould growth. Typical indicators include:

• Persistent musty odours.
• Previous flooding or water damage.
• Plumbing or roof leaks.
• Visible staining or suspected mould growth.
• High indoor humidity or condensation.
• Moisture problems associated with ventilation systems.

During an inspection, particular attention is given to identifying the source of moisture, since mould remediation is unlikely to be successful unless the underlying cause is addressed. Inspectors typically examine plumbing systems, roofs, windows, foundations, drainage, condensation risks and the condition of building materials including plasterboard, timber, insulation, flooring and ceilings. Bathrooms, kitchens, utility rooms, roof spaces and sub-floor voids are commonly assessed for ventilation performance and humidity levels.

[edit] Understanding inspection findings

Inspection findings vary according to the condition of the building and its moisture history.

Where no active mould growth is identified, the inspection may indicate that moisture levels are adequately controlled and ventilation is functioning effectively. Nevertheless, buildings should continue to be monitored following flooding or significant water ingress.

In some cases elevated moisture levels may be detected before visible mould develops. Early identification allows repairs to be carried out and affected materials to be dried before mould growth becomes established.

Localised mould growth may occur around windows, plumbing fixtures or poorly ventilated rooms, often as a result of condensation, minor leaks or inadequate ventilation. Successful remediation normally requires both removal of the mould and elimination of the moisture source.

Where air sampling indicates elevated concentrations of mould spores, further investigation may be required to determine whether hidden mould growth, concealed water ingress or contamination within ventilation systems is present. Air sampling results should always be interpreted alongside the findings of the building inspection.

[edit] Preventing mould growth

Preventative maintenance is the most effective means of reducing the risk of mould development. Good practice includes:

• Repairing plumbing leaks promptly.
• Repairing damaged roofs without delay.
• Maintaining indoor relative humidity within recommended levels.
• Using extract ventilation in kitchens and bathrooms.
• Providing adequate ventilation to roof spaces and sub-floor voids.
• Cleaning gutters and rainwater goods regularly.
• Directing rainwater away from building foundations.
• Drying wet building materials as quickly as possible after water ingress.
• Regularly inspecting areas susceptible to dampness.

A mould assessment may be particularly beneficial following flooding, before purchasing or selling a property, after significant plumbing failures, or where persistent dampness or musty odours cannot readily be explained.

[edit] Conclusion

Mould growth frequently develops as a consequence of persistent moisture problems that may remain concealed for extended periods. A systematic mould assessment can help identify hidden water ingress, assess building conditions that encourage mould growth and support informed maintenance decisions. Early investigation and prompt remediation of moisture problems can reduce deterioration of building materials, improve indoor environmental quality and minimise the likelihood of recurring mould growth.

[edit] Related articles on Designing Buildings

• Damp proof course (DPC)
• Damp
• Condensation
• Dry rot
• Wet rot
• Building pathology
• Building survey
• Indoor air quality
• Mould
• Ventilation