You’ve heard about mold concerns in schools and other public places, but you probably haven’t thought much about the prospect of it in your hog facilities, office or other workplace spaces. 

Yet moisture that gets locked within the walls or ceilings of your buildings can lead to mold and other problems. During construction you have to be vigilant about so many things, but paying attention to moisture control is a long-term investment. The key is to avoid excess wetting, insufficient drying and closing up a wet area prematurely. In most cases where you control moisture, mold growth won’t be a problem.

“Livestock facilities must be designed for rain- and air-leakage control, as well as to allow drying of incidental moisture,” says Ron MacDonald, agricultural engineer, Agviro, Guelph, Ontario. “Ventilation, particularly during cold weather, is an essential control requirement.” 

Actually ventilation is the only way moisture leaves the building so it needs to be done right.

It may not be an easy task, but certainly it’s an on-going one. MacDonald offers some tips to avoid moisture problems in your facilities.


  • Ensure that animal manure and urine can’t collect on the floor, alleyways or in-service hallways for any length of time.
  • The same goes for any water that the animal splashes or wastes.


  • Regularly check for and repair any leaky waterers, pipes and valves throughout the building.
  • Train operators how to properly use and maintain high-pressure washers. This helps prevent from over-spraying into attic and wall spaces.
  • To prevent moisture from entering through the top of electrical boxes, ensure that conduit and wiring enter through openings only from the side or bottom.


  • Drain surface water away from the building’s exterior to minimize water from splashing and pooling. Install flashings for additional assistance. These steps will help maximize foundation dryness.
  • Ensure that solid floors are sloped properly to accommodate drainage. Also see that drains leading to storage are properly sized, located and managed.
  • Attic venting provides a cold roof deck, which prevents thaw/freeze problems from developing.
  • Make sure there’s adequate insulation in the structure. This includes preheat ducts that have cool air in or around them.
  • Thermal bridges occur at studs and posts within walls. Use spacers behind studs to allow insulation to fill the space (warm side only.) On interior walls there can be a big temperature difference (+50° F) between the room air and the wall surface temperature in front of the stud.
  • Caulk around doors, wall and ceiling joints (beware of trim covering poor workmanship) to seal air leaks. Also caulk around windows, exhaust ventilation fans and air inlets.
  • Minimize locations where manure can collect on support posts, walls and beams.
  • Ensure that ventilation air doesn’t short-circuit into soffits or the attic air space.
  • See that the design provides adequate soffit venting as well as roof-peak venting.
  • A target for room negative-air pressure should be about 0.05 inches water column, with 0.08 inches per water column in the summer. Neutral and positive pressure create opportunities for increased moisture-load problems in the structure.
  • To retard water-vapor migration, all facilities require a combined air/water-vapor barrier, properly installed and ship-lapped at all joints, and sealed with silicone.

Granted some of these steps are easiest to implement and monitor during new construction. However, some can be incorporated into a retrofit plan, and still others are worth the effort to tackle on their own.