BUILDING SERVICES & SURVEYS
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:
 

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

(See Flat Roof Surveys below)

DAMP – RELATIVE HUMIDITY – MOULD

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 case 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 building envelope and the heating ventilating and air conditioning (HVAC) system must maintain proper humidity levels inside the building. Mould and mildew will otherwise grow under inadequate conditions. Maintaining positive internal building pressure and humidity levels, below 60%, is essential to provide 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 required for growth.

Damp wall - note area beneath vent.  Light areas show heat conduction through the wall to the outer surface.

Flat Roofs

Horton Levi specialises in flat roof surveys and inspections. 

We have developed techniques to 'Map' the extent of moisture or water ingress beneath the roof felting or covering.  In most cases, the source of the ingress is apparent from the infra-red data. Because we can usually pinpoint the areas where there is moisture beneath the felting and trace the path of entry, these specific areas can be repaired.  Most roofing companies will repair large sections to ensure the problem is contained however this can be very costly compared with our survey. Our surveys are totally impartial and we are not connected or associated in any way with roofing repair companies. Damp or moisture is a very efficient conductor of heat energy, and under the right conditions, rising and/or penetrating dampness can be visualised through a thermal imager giving the precise boundaries of the problem saving a vast amount of time using conventional damp meters. Please contact us for our brochure.		The images below are a photograph and a typical thermal image showing moisture beneath the roofing felt. Yellow areas show moisture beneath roofing felt
Horton Levi specialises in locating water leak entry points in buildings. Much of our work is with commercial buildings and flat roofs. Our company has provided this service since 1992 and has constantly invested in the latest equipment as well as developing our own. Our investigation services can employ some or all of the following techniques: Thermal infrared roof scanning Capacitance measurements Radio Frequency equipment Endoscopic equipment Fluorescent Dye applications Conductivity testing		Red in this thermal image is underlying moisture.  Moisture trails show that water is entering from the parapet.
Using advanced rectification techniques, we can overlay a thermal image with a photographic image. This enables easy identification of problem areas as shown in the example on the right.
The image to the right is a blend of the thermal and photographic images above.  Red shows the underlying moisture.
Depending on the type of roof and materials, apart from the infrared, some of the above techniques are limited, especially where there is extensive plant. Please call us at any time for information on your specific requirements.

For further information on flat roofs see www.thermal-imaging-survey.co.uk