Understand Water Loss Monitoring
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These steps will be used after either Day 1 is complete or the initial water removal and demo has been completed. These processes are to ensure the equipment is running correctly and the drying process is taking place.
Step 1: Understand the effectiveness of advanced structural drying techniques
This overview will show the effective of the advanced structural drying techniques that are used to when drying water damaged buildings, using comprehensive knowledge and tools.
With a reasonable understanding of psychometrics, restorers can often dry and restore materials, which in the past were demolished and rebuilt. Science and best practices to dry building materials using airflow, amplified dehumidification, and controlling temperature/energy provide exceptional results to dry structures.
Step 2: Understand the monitoring timeline
Monitoring is the activity of monitoring the job site after the initial demo / extraction day has been complete. You are checking to verify that the drying equipment is performing they way it should and the room is starting to dry.
***If you arrive on site on your first day of monitoring and there is standing water, stop what you're doing. Check the source of the loss to ensure it has been repaired or capped and find out where this water has come from. Some times pressure builds up in a line and cause cause secondary damages in the pipes. Once the source has been stopped, you will need to extract any standing water as the drying equipment will not operate properly until the standing water is gone.
Step 3: Understand the types of drying
Depending on the type of water loss there are two main types of drying used:
- Disruptive - This drying method involves removing wet items, injecting air to speed up drying, or perforating surfaces to allow water to evaporate. Disruptive methods are used when contamination, damage, cost, or customer concerns require removal or manipulation of the affected material.
- Aggressive or "in place" - This drying method involves leaving wet items in the structure and drying them in place using warm, dry, direct airflow. Aggressive methods are used when contamination and damage are not concerns, and when it s cost-effective to dry an item instead of replacing it.
Knowing the differences between these two techniques will help you monitor the data on how the area is drying as each will take different amounts of time to dry.
Step 4: Take daily moisture readings
Daily moisture readings should be included in the drying record to include air, equipment, and HVAC systems. Moisture content levels for wet structural materials should be recorded in a moisture content spreadsheet to show the progress of drying. These recorded moisture content readings will show that the building is back within an acceptable range of the pre-loss condition. It is important to know that air records alone will not prove that a building is dry.
After 24 hours the psychrometric conditions will demonstrate if sufficient dehumidification is being used or if adjustments are needed.
The psychrometric chart provides us with the tools to evaluate which drying equipment or methods will be the most effective. It is imperative to determine if conditions are achievable within the drying chamber based on the outside temperature and specific humidity for a refrigerant or desiccant dehumidifier, or a heating unit. These conditions can assist in determining what equipment to use on any loss.
Step 5: Understand the monitoring tools and equipment
These are some of the tools professionals use to measure, monitor, and evaluate during the drying process of a structure:
- Moisture sensor – senses moisture in materials over 17% MC; helps determine perimeter of water damage; unable to determine which layer is wet or when dry
- Thermo-hygrometer – determines temperature/RH in all required atmospheric areas of inspection; helps determine open or closed drying system; further determines dehumidifier requirements after initial placement
- Moisture meters – invasive and non-invasive; determines moisture content; establishes, monitors, and determines when dry standards are met
- Miscellaneous – infrared camera and thermometer; manometer; borescopes; data loggers
Step 6: Use air movement
Rapid air movement across wet surfaces of materials or assemblies is a critical component of effectively and efficiently drying the surface of those materials and assemblies.
Conditions conducive to drying at the surface differ from moving excess moisture within the materials or assemblies. Rapid air movement across the surface of material becomes less important relative to vapor pressure as the focus of removing surface moisture gives way to reducing moisture content in low evaporation materials.
The constant and falling rates of drying materials require different criteria for changing conditions.
Step 7: Use dehumidifiers
You will want to take your reading to verify that the dehumidifier is running properly and following your drying goals.
Refrigerant dehumidifiers work best 70-90 degree F range (generally, best around 85 - even when using high-temp LGRs).
Every 20F rise in air temperature approximates cutting RH % in half.
- Refrigerants – Most efficient operating conditions 70-90F. (most energy efficient is an LGR)
- Desiccants – most efficient with incoming air from coolest/driest air possible; capable of creating greatest pressure differentials (air and vapor pressures); produces low humidity ratio (gpp) important to dry Class 4 materials, dense materials, and complex systems.
- Uses - closed-drying environments; multiple layers of materials; security limitations; high outside (and inside) humidity conditions; no ventilation ports; basement areas
Step 8: Understand humidity, temperature, and airflow
These factors influence the movement of moisture within a material as well as the evaporation rate from the surface of the material and can greatly impact the overall drying time for a project. It is important to quickly control the moisture in the air and use sufficient airflow to dry the surface of materials to reduce water activity, thus lowering the potential for microbial growth. If the surfaces of hygroscopic materials can be dried and maintained below 0.75, microbial growth can be quickly halted, even though the core of the material may still have elevated moisture content.
As the job progresses and the environment is stabilized, materials can be dried by managing the humidity, airflow, and energy (heat). Further into the drying, air movement should be re-directed and ensure good transfer of energy to the remaining wet areas. The overall need for humidity control and airflow can be lower than at the beginning of the project since there is significantly less moisture in materials being evaporated during the latter stage.
Humidity, airflow and temperature “HAT” work together and when managed, enable achieving target time for drying. This is because of their movement toward equilibrium - wet seeks dry; hot seeks cold; high vapor pressure seeks low vapor pressure.
Step 9: Activate off-site assets
Be sure to utilize any site assets you have for the drying process.
Examples
- ceiling fans
- whole-house fans
- exhaust vents
- HVAC
- When conditions allow open home drying
Step 10: Document and communicate with he insured
Make sure you have your reading time stamped and documented and set your schedule with the insured for the next day.
