The Drying of Heritage Properties

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The Drying of Heritage Properties

• Nigel Hewitt
• Technical Manager

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Communication

• Establish good lines of communication
• Project Managers
• Insured
• All other relevant parties

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Goals

• What are trying to achieve
• What was pre loss condition
• Indoor Atmosphere
• 18ºC - 22ºC
• 40 - 60 Relative Humidity
• Can we find a Dry Standard
• How Dry was the property pre-incident

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Goals

• Where is the moisture located
• Moisture Meters
• Moisture sensors
• Penetrating
• Non-penetrating
• Thermal Hygrometers
• Thermography
• Boroscopes

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Goals

• Whats Wet
• What kind of materials
• Structural or decorative
• How Wet is it
• Which is the most appropriate drying system
• Open
• Closed
• Combination

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The Drying Process

• Water is present in one of three forms
• Surface Water
• Very easy to dry
• Free Water
• Easy to dry
• Bound Water
• Harder to dry

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What Effects The Drying
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Moisture Movement

• Moisture movement occurs when there is a vapour
  pressure imbalance between materials and
  environments
• Moisture movement ceases when there is vapour
  pressure equilibrium

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Permeance

• Ability of moisture to pass through materials
• Based on
• Vapour Pressure
• Temperature
• Relative Humidity
• Pore size

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Considerations

• Permeability of different materials
• Connected materials with different rates of
  permeability
• Vapour Barriers
• Where are they located
• Can they be perforated
• Can they be removed
• Hidden cavities

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Considerations

• Secondary Damage
• Moulds
• Dry Rot
• Wet Rot

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Drying Equipment

• Airmovers
• Essential part of drying process
• Velocity, pressure and placement effect
  performance
• Airmover Types
• Carpet dryers
• Inter-air dryers
• Axial fans
• High volume airmovers

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Dehumidifers

• Types of dehumidifier
• Domestic refrigerant
• Commercial Refrigerant
• LGR
• Desiccants
• Humididstats

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Alternatives

• Heat drying systems
• Is it safe
• Low level back ground heat
• Controlled Ventilation
• Dry Slowly

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Considerations

• Surface finishes
• Limewash
• Paints
• Wood panelling
• Fabric
• Leather

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Areas of Concern
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Areas of Concern
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Target Drying

• Ducting
• Simple way to improve drying

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Target Drying
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Target Drying
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Target Drying
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Target Drying
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Target Drying

• Drying Hardwood Floors
• Apply positive air pressure one side
• Negative pressure on the other
• Greatly increases drying efficiency

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Target Drying
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Target Drying
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Target Drying
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Target Drying

• Injection Drying
• Dries voids and cavities
• Use positive and negative pressure
• Reduce claim duration
• Equipment can be expensive

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Secondary Damage
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Secondary Damage
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Secondary Damage
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Contents
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Monitoring

• Where is the moisture located
• Moisture Meters
• Moisture sensors
• Penetrating
• Non-penetrating
• Thermal Hygrometers
• Thermography
• Data Loggers
• Remote Monitoring
• Calcium Carbide

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Data Loggers
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Data Loggers
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Remote Monitoring

• Continual Monitoring
• Temp
• Rh
• Specific Humidity
• Dew Point
• Set Thresholds
• Alarms

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Calcium Carbide

• Measures moisture content in materials
• A weighed sample is added with calcium carbide
  into the pressure vessel
• Chemical reaction produces acetylene gas
• The increase in pressure can be read directly
  from a calibrated pressure gauge

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In Summary

• Determine whats wet and how wet it is
• Check all unaffected items
• Select appropriate drying system
• Monitor frequently and accurately
• Flood Prevention

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Thank You

• Any Questions