Making Adjustments to the Drying System
December 22, 2009
The absolute constant in a wet structure is change. Change, when controlled closely, will be positive: that is, a change toward pre-loss condition. If wet materials are not drying, it is necessary to force progress by other means. These are necessary adjustments to the drying system.
Monitoring for ProgressEvery 24 hours of drying, materials are re-inspected to determine if drying progress was made. As each material’s progress is documented, equipment and processes are adjusted as follows:
- Material is Drying – If the material is drying, continue with the current drying approach. It is working properly and progress is being made
- Material has Dried – If the material has achieved its drying goal, reposition equipment to focus on other areas or remove it from the structure.
- Material is Not Drying – If the material is not making progress, your approach is not working and you need to modify your methods. You’ll need to change the equipment, or consider removing saturated material, depending upon which approach is most economical.
It's Drying!If a wet material is making significant progress, keep doing what you’re doing. No changes are necessary. Some of the worst decisions I see made on drying jobs occur when people try to fix something that isn’t broken.
It's Dry!When a wet material has finally reached dry standard, stop drying it. Focus your drying efforts on materials that are still wet. Consider reducing the amount of equipment.
A perfect example of this principle is when the carpeting is dry, but the subfloor or concrete underneath is still wet. Many restorers assume that all the air movers needed for the drying of carpet and underlay would help the subfloor dry. This is not the case.
In multiple experiments with air movement, I have found no benefit to continuing with high numbers of air movers after carpet and underlay is dry. Air movers can be reduced at this point because subflooring evaporates much slower than carpet and underlay. To continue to apply high levels of air movement over dry carpet is overkill.
Say you have a class 2 job: wet carpet and underlay, wet subfloor that needs to be dried. On Day 1, you would place air movers every 10 to 16 lineal feet. If extraction was done correctly, the carpet and underlay should be dry within 24 hours. Starting on Day 2, you should be able to reduce the number of air movers. Ultimately, you can bring the number down to class 1 levels – one air mover every 150 to 300 square feet, one per area. (This example assumes that the walls are not affected. Keep air movers running along walls until they are also dry.)
It's Not Drying!If a wet material is not making significant progress, it is critical to re-evaluate the material in three ways:
- Contamination – Now that it has been wet for another 24 hours, is there a concern for microbial contamination? Can this contamination, if present, be treated properly? Should the material be removed to ensure complete removal of the contaminant, if present?
- Damage – Now that the material has been wet for another 24 hours, has damage become evident, such as warping, swelling, splitting or staining? Can the damage be restored, cost effectively?
- Cost – The current system is not working and must be changed. What will result in the lowest cost – removal and replacement or more aggressive drying?
Change Equipment to Force ProgressWith the variety of installations in a structure, it can be difficult to determine the best approach to drying a material or surface. But no matter how complex a situation, the basic rules of psychrometry still apply:
- Wet items will dry faster if drier air is supplied, with more direct airflow and warmer material temperatures.
- Restorers can rely on this principle when drying challenges are present.
Drying WallsWith their wide variety of surfaces and complex internal structures, wet walls present a significant challenge to restorers. For basic walls with a single layer of wallboard and flat paint, the only drying tool needed is an air mover blowing warm, dry air along the wall.
But in structures where wall surfaces are covered with non-permeable covering or there are multiple layers of wallboard, it may be necessary to remove base molding, drill holes and introduce air movement. Airflow in the wall cavity increases the rate of evaporation and allows the wall to dry from both inside and out.
If a wet wall is not making progress after 24 hours of drying, there are several options for action:
- Add more direct airflow on the outside of the wall.
- Move the dehumidifier output so that it is closer to the wet surface.
- Carefully remove baseboard and continue airflow along outside of wall.
- Drill holes below baseboard level to allow wall to breathe and continue airflow along outside of wall.
- Blow direct airflow into the wall using air movers or inter-air dryers.
- Feed air movers that are blowing into wall with a dehumidifier.
- Warm wall surfaces with heat.
- Completely remove all wet wallboard and all wet insulation.
Drying FloorsIf a wet floor is not drying, it is important to remember the basic rule regarding evaporation: evaporation will increase as materials are made warmer, as air is made drier, and as air is moved more rapidly across the wet surface. Under this principle, there are several options for action beginning with the least disruptive:
- Add more direct airflow on the surface and subsurface of the floor.
- Provide drier air to the floor with desiccant dehumidification.
- Dry the floor from both the bottom and top (“sandwich drying”).
- Feed air movers that are blowing into the floor with dehumidifiers.
- Warm floor surfaces with heat.
- Remove wet flooring completely.
Drying CabinetsWhen drying cabinets, restorers seek ways to minimize damage while ensuring that the materials dry thoroughly. Specialized equipment is available to generate and direct warm, dry airflow in hidden structural cavities.
Most access to a standard cabinet is through the toe kick, a cosmetic cover which hides the under cabinet support. This toe kick is easily replaced in all standard installations. If access is not available through the toe kick, holes are drilled through the shelving in the bottom of the cabinets, through the wall immediately behind the cabinets, or through the back wall of the cabinet itself.
Regardless of the method used, it is important to ensure that the amount of water and the location of water are both identified and monitored. Drying systems are adjusted as progress, or lack of progress, dictates.
SummaryThe most successful restorer will apply the tools and techniques that are best suited to each unique structural drying project. This requires an array of tools to control humidity, temperature and airflow in a variety of circumstances, and the knowledge to employ each tool properly. It is critical to diligently and thoroughly evaluate the change in materials over time, and adjust the drying system as progress dictates.
A drying job site is a dynamic environment where change is constant. The change desired in drying is movement toward a pre-loss condition – by first creating a clean, safe environment and then assessing potential damage. Because the job is not complete until materials are clean, dry, and equal or better in appearance and function than when the loss occurred, the impact of each decision must be evaluated closely.
Ultimately, decisions must direct the work toward the safest and most cost-effective process available to achieve this goal.