Maintaining Ideal Relative Humidity (RH %) in Poultry Houses

Posted by Jones-Hamilton Co. on May 5, 2020
Jones-Hamilton Co.

As producers work to remove moisture from poultry houses, it’s important to understand that temperature plays a critical role in the amount of water air can hold. Humidity describes how much water is in the air; for example, at 100% RH air is at its maximum water holding capacity, while at 90% RH the air can absorb a little more water. Humidity levels of 40% allow for the air to absorb a significant amount of moisture which can then be removed from the house through ventilation.


Since the capacity of air to hold water varies based on temperature, the term relative humidity is used to identify the moisture absorbing capacity based on temperature differences. In general, the ability of air to hold moisture doubles for every 20 degree rise in temperature. For example, 1,000 cubic feet of 40°F air can only hold less than eight ounces of water, but 1,000 cubic feet of 85°F air can hold about 32 ounces.1

Why Manage Relative Humidity?

By ventilating poultry houses to target relative humidity (RH) level of 40-60%, producers prevent moisture build-up which presents itself as litter stickiness, and an increase of the thicker, mud-like dust on equipment that is difficult to remove. Managing RH also aids to decrease ammonia formation and paw lesions. In fact, studies have shown that poultry houses with a 45% RH have lower ammonia levels and less litter caking.

How to Manage RH

The moisture producers need to manage is what is inside the house. Therefore, rainy days do not require a reduction in timer fan settings so less moisture is brought in. Instead, focus on bringing in air through inlets so it is properly directed along the warm ceiling and can mix with warm air and dry out. During downtime, check the operation of inlets and inlet machines to ensure they are opening and closing properly, and do not have air leaks. Checking for proper static pressure will also help with ideal air flow. Each morning, check relative humidity with a handheld humidity meter first thing and increase fan time if levels are too high.

As we discussed in the last blog in the series, the condition of your equipment will greatly impact the effectiveness of your ventilation. Since humidity plays a major role in the amount of dust buildup, solutions that minimize or simplify the buildup of dust are highly valuable. For example, SWASHDUST-REPEL™ actually repels moisture to change the way dust adheres to a surface while decreasing the amount of overall dust buildup. SWASHDUST-REPEL™ makes dust easier to remove, which decreases cleaning time and allows fans to operate at maximum efficiency.

In addition, SWASHCOOL-CELL™ improves airflow for maximum ventilation efficiency by removing mineral scale from evaporative cooling pads. And by reducing the amount of time needed to clean evaporative cooling pads by 30-50%, producers have more time to spend on the maintenance of other house equipment.

Learn more about SWASHDUST-REPEL™ AND SWASHCOOL-CELL™ and how these products can play a role in the proper management of house relative humidity.



SWASH™ is owned by Jones-Hamilton Co., a leading provider of science-backed solutions to the animal agriculture industry. Led by industry veterans who understand the challenges faced by producers, the SWASH™ team is dedicated to providing reliable, high-quality chemicals backed by dependable customer service and knowledgeable technical support. Our team knows that every penny matters and works continuously to ensure value, maximize efficacy, and enhance the bottom line.


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