Before attempting to restore nonresidential buildings that have been exposed to floodwaters, evaluate the extent of damage and the amount of cleanup and repairs necessary.

“The first thing that needs to be done with a building that has survived a flood is to check its structural soundness,” says Ken Hellevang, North Dakota State University Extension Service agricultural engineer and flooding expert. “If the building has been moved, shifted or twisted, it may not be safe to enter.”

Also, while damage is obvious in many cases, some damage may not be noticeable immediately and could weaken the building or cause other problems.

If the building has extensive damage, tearing it down and rebuilding probably will be less expensive than trying to repair the damaged structure, Hellevang says. As a rule of thumb, if repairs and restoration cost more than 60 percent, building a new structure generally is the best option.

Damage Assessment

Hellevang recommends building owners do a thorough inspection of the structure. That should include checking whether the ridge and eaves are straight; walls are vertical and straight; the building has shifted on its foundation; and frame members, such as knee braces, have been pushed into the siding or up into the roof.

The inspection also should include an examination of:

• Trusses and rafters for signs of crushed, split or broken wood
• Frame members to make sure they haven’t buckled or twisted, aren’t bowing out of alignment and don’t appear to have slipped relative to each other or have gaps in a truss joint
• Gussets for signs of being deformed
• Connections for indications that nail, screw or bolt holes are elongated and nails or other connectors are pulled out of the wood or bent
• Posts of pole buildings for crushed or broken wood near the ground or at truss connections or knee braces. Make sure the posts are straight and vertical. Look for indications that posts made of more than one board may have split along rows of nails.
• Doors or windows to make sure they open as they did before flooding. If they do not, this may indicate the structure has shifted. In cases of severe shifting, water lines, gas lines and electrical circuits may have been damaged.
• Electrical circuits or insulation for wetness and other water damage
• Siding and metal roofing for tears around fasteners, evidence of fasteners being pulled, bends or buckles in the metal roof sheets and whether the sheets still are aligned with each other
• Wood for indications of rotting or other damage that could weaken the building. Document the damage with photos and contact your insurance company.

Hellevang recommends building owners consult with a building contractor or engineer if they see several indications of damage.

Restoration

Hellevang suggests that once floodwaters recede, dry out the building as much as possible. This can include using a sump pump, mops, fans and/or natural ventilation. When the structure is dry:

• Inspect laminated woods, such as plywood, that have been immersed in water to be sure laminations still are firmly bonded together. Check nails to determine whether they still are firmly in place.
• Remove silt and mud from floors. Wood floors that have absorbed a lot of water could be buckled. Do not repair them until they are fully dried. Pulling some of the flooring back into place with nails may be possible. Plane and sand the floors as needed to remove humps. This may not get the floors into condition to look good uncovered, but they will be smooth enough to serve as a base for a new covering.
• Remove any wet insulation. Floodwaters often will leave absorbent material with a foul odor that is difficult to remove. When checking the insulation, expect it to be wet above the high-water level because of the material’s wicking action.
• Replace any drywall. However, interior sheathing in out-buildings usually will be wood, which can be removed, dried and reused.
• After removing interior sheathing and insulation, inspect the wall studs, sills and plates for structural damage, and repair or replace damaged components.
• To replace insulation in the walls, place a 4-mil or 6-mil polyethylene vapor barrier on the warm side of the insulation according to local building recommendations and then install interior drywall or sheathing.
• Inspect wiring and plumbing for damage. Electrical outlets, switches, sockets and breaker or fuse boxes generally need to be replaced. Check local electrical codes. Do not turn on the power to a flooded structure until it has been inspected and determined safe by a qualified person.

Here is advice for flooded farmsteads:

Livestock Building Equipment

Disconnect equipment that was immersed in floodwaters, such as milking equipment, grain augers and ventilation fans, from the power source and completely disassemble and thoroughly clean it to remove grit or other contaminants.

Do not run electric motors that were submerged until they have been reconditioned by a qualified person. This means air conditioners, furnaces, appliances, feed augers, fans and other equipment may not be available for several days.

Alternatives may be necessary to get a flood-damaged farmstead back into operation. This could involve moving dairy cows to a neighbor’s milking unit, utilizing natural ventilation instead of mechanical, and feeding by hand. Animals housed in mechanically ventilated buildings may need to be moved to prevent acute exposure to hazardous gases.

Water Systems

If the farmstead’s water supply comes from a well, test the water to determine if it is safe for human or livestock consumption. A well that has been contaminated by floodwaters will need to be cleaned and sanitized.

If a rural water system supplies the water, check for breaks or leaks in the supply and distribution pipes. Also, flush all the water lines after the flood.

Fuel and Chemical Storage Areas

Special cleanup and disposal measures may be needed if fuel or chemicals are spilled or have water damage. Your county Extension office has information on safe cleanup methods.

Farm Shops

Clean, dry and lightly oil all metal tools to prevent rusting. Power tools will need reconditioning before they can be used. Floodwaters leave deposits in motors that may cause electrical faults, creating a safety hazard.

“Cleaning up after a flood presents many problems,” Hellevang says. “Try to remain calm. Survey the farmstead, evaluate the amount and location of the damage, and then prioritize the necessary cleanup.”

For more information, visit NDSU’s flood information Web page at http://www.ag.ndsu.edu/flood.

NDSU Agriculture Communication