Relative Humidity, Moisture, Damp, Air Quality, Condensation, Water Leaks

Horton Levi damp detection surveys include in-depth physical inspections, endoscope intrusive investigations, where required, and 8-14 micron infra-red scanning of walls and roofs as appropriate. Comprehensive investigations are also available and can include some or all of the following services (which include these key areas of inspection):

• Building Ventilation Systems
• Carbon Monoxide Concentrations
• Temperature / movement
• Relative Humidity
• Dust Concentrations
• EMF. Electromagnetic Fields – Leakage and Emissions
• Infrared Thermography to identify areas of high moisture / Heat Loss
• Radio Frequency metering for sub-surface moisture inspection
• Electromagnetic wave inspection to ‘map’ and trace damp.
• Endoscopic Video inspections

Hard copy reports and all survey data on CD for client viewing / archiving on a PC is standard as a part of our services.

Do you have a specific interest in roof damp surveys? Horton Levi can help.

Damp, Relative Humidity, Mould

The thermal infrared image below is an internal view of a plastered wall. In many circumstances, the thermal data of the brick or block wall will appear as if there is no plaster covering. The Mauve and dark Blue is dense rising moisture. A wide view of the wall would pictorially show the full extent and travel direction of the moisture.

This thermal image below has been blended with a photograph. The Yellow / Green areas show dense moisture and how it has travelled down from the parapet.

Relative Humidity is usually measured as a percentage of water vapour in the air. The amount of vapour contained in the air can vary with air temperature and pressure.

‘Comfort Level’ - Effect of Humidity / Temperature Variations.
The effective ‘comfort level’ in a home or office can vary with temperature and humidity. Below about 14° C, humidity has little effect on temperature feel but at normal house / office heated temperatures of about 22°C, there can be a significant difference in ‘comfort level’. When humidity is low, a normally warm temperature can feel cool owing to faster evaporation of body perspiration. Conversely, in higher humidity situations, perspiration is slowed providing a warmer feel at the same temperature.

Heating, Ventilation, and Air-Conditioning (HVAC) systems
HVAC systems should provide air at comfortable temperature and humidity levels and filter indoor air contaminants. HVAC systems that are poorly operated or maintained can contribute to poor indoor air quality.

Effect on Buildings and Contents
Many materials (wood, plaster, decorative / paintings etc) absorb water vapour from the air. Materials will therefore absorb more moisture in high humidity situations and release moisture as the humidity lowers.

Moisture soaked plaster or plasterboard can in some cases damage paintings, clocks, musical instruments, building components etc.

Further effects and consequences of high humidity is condensation behind plasterboard walls that can result in structural damage and can provide perfect conditions for the growth of mould and mildew.

Ideally during the winter months an office should be about 22°C with a relative humidity between 30 and 60 percent. During the summer months, an indoor temperature of about 20°C with a relative humidity (UK) between 40 to 60 percent is considered normal.

Computers, office equipment and paper products can be adversely affected by high humidity and shorten their life.

A heating ventilating and air conditioning (HVAC) system must maintain proper humidity levels inside the building to prevent mould and mildew will otherwise growth. Maintaining positive internal building pressure and humidity levels, below 60%, is essential to ensure proper indoor air quality in buildings.

Exhausting air from rooms like toilets, cafeterias and other areas without replacing it, creates a negative pressure that draws unconditioned air through exterior walls, windows and doors. As the outside air is drawn into a building by the negative pressure that is created by air movement or exhausts, the moisture in the air may condense when it comes in contact with the cooler surfaces. The condensation provides the moisture fungi requires for growth.