Buildings that have been exposed to flood waters need to be evaluated for the extent of damage and the amount of clean-up and repairs necessary to restore them to a useable condition.
The first thing that needs to be done with a building that has survived a flood is to check its structural soundness. If the building has been moved, shifted or twisted, it may not be safe to enter. Check the foundation, sill plate, roof supports and walls for damage. If there is extensive damage to the building, it probably will be less expensive to tear it down and start again with a new building as compared to attempting to repair the damaged structure.
Consider, though, that while storm damage to structures is obvious in many cases, that which is not immediately noticeable also could weaken the building or cause other problems.
Building owners should do a close inspection of the structure from the outside to check for damage, advises Ken Hellevang, a North Dakota State University Extension Service agricultural engineer. He says they should check whether the ridge and eaves are straight, walls are vertical and straight, and the building has not shifted on its foundation. They also should look for indications that frame members, such as knee braces, have been pushed into the siding or up into the roof.
Examine the trusses and rafters for signs of crushed, split or broken wood. Determine whether any members buckled, twisted, are bowing out of alignment, appear to have slipped relative to each other or have gaps between members in a truss joint. Also see whether the gussets show signs of being deformed. Look carefully at connections for indications of nail, screw or bolt holes being elongated, and see whether nails or other connectors are pulled out of the wood or bent.
Hellevang notes that an inspection for structural damage also should include:
"Buildings that show signs of damage will need to be repaired," Hellevang says. "Truss members may need to be replaced or additional boards placed from joint to joint. Additional and larger gussets may be required for damaged joints. Additional nails or screws may be required. Nails and screws should not be placed too close to each other or they may weaken the wood.”
Hellevang warns that cost of repairs may exceed the value of the building in some cases, and suggests building owners consult a building contractor or engineer if they see several indications of damage.
"The value of machinery, vehicles and equipment stored in a building can be several hundred thousand dollars," he says. "It does not make sense to put that value or yourself at risk with a building that is structurally damaged.” Once the water has subsided, he suggests, dry out the building as much as possible. This can include using a sump pump, mops, fans and/or natural ventilation.
After wood dries, inspect laminated woods, such as plywood, that have been immersed in water to be sure laminations are still firmly bonded together. Check existing nails to determine whether they are still firmly driven.
If the building was insulated, the wet insulation must be removed. Floodwater 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 wicking action of the material.
If the interior wall sheathing is drywall, it will need to be replaced. Usually the interior sheathing in the out-buildings will be wood which can be removed, dried and reused. After the sheathing and insulation are removed, inspect the wall studs, sills and plates for structural damage. Damaged components will need to be repaired or replaced.
Inspect wiring and plumbing for damage from the flood’s pressure. Electrical outlets, switches, sockets and fuse boxes generally need to be replaced. Check local electrical codes.
Note: Do not turn on the power to a flooded structure until it has been inspected and determined safe by a qualified person.
After the buildings have dried sufficiently, renovation can begin. All floors probably will be covered with layers of silt and mud. This will need to be removed. Wood floors that have absorbed a lot of water could be buckled. Do not repair them until they are fully dried. It may be possible to pull some of the flooring back into place with nails. Plane and sand as needed to remove humps in the floor. This may not get it into condition to look good uncovered, but it will be smooth enough to serve as a base for a new covering.
Insulation will need to be replaced in the walls. Cover with a 4 mil or 6 mil polyethylene vapor barrier on the warm side of the insulation according to local recommendations and then install interior drywall or sheathing.
Livestock-building and electrical equipment – After disconnecting them from the power source and completely disassembling them, thoroughly clean milking equipment, grain augers, ventilation fans and other items that were immersed in the flood waters to remove grit or other contaminants. Do not run electric motors until they are clean, dry, free-running and judged safe by a qualified person. This means that air conditioners, furnaces, appliances, feed augers, fans and other equipment may not be approved for use 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 system – If a well is used for the water supply, test the water to determine if it is safe for human or livestock consumption. A well that has been contaminated by floodwaters usually can be cleaned and sanitized. If a rural water system is being used, check for breaks or leaks in the supply and distribution pipes. It also would be good to flush all your water lines after the flood.
Fuel and chemical storage areas – If these supplies are spilled or have water damage, special measures may be needed for proper and safe cleanup and disposal. Your county Extension office has information on the methods necessary for safe cleanup.
Farm shop – Clean, dry and lightly oil all metal tools to prevent rusting. Power tools will need individual cleaning and drying before they are used. Belts, nails, screws, etc., will need to be dried to prevent rusting.
Cleaning up after a flood presents many problems. Try to remain calm. Survey the farmstead, evaluate the amount and location of the damage, and then prioritize the necessary cleanup.