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Cleaning and Repairing Flooded Basements
Before you enter a flooded basement:
- Turn off the electricity, preferably at the meter.
- Check outside cellar walls for possible cave-ins, evidence of structural damage or other hazards.
- Turn off gas or fuel service valves.
- Open doors and windows or use blowers to force fresh air into the basement.
- Do not use an electric pump powered by your own electrical system. Use a gas-powered pump or one
connected to an outside line. Fire departments in some communities may help with such services.
- More damage may be done by pumping water from the basement too soon or too quickly, than from letting the floodwater remain. Water in the basement helps brace the walls against the extra pressure of water-logged soil outside. If water is pumped out too soon, walls may be pushed in or floors pushed up. To help prevent such structural damage, pump the water from the basement in stages. Remove about one-third of the water each day. Watch walls for signs of failing. If the outside water level rises again after the day's pumping, start with a new water line. The soil may be very slow to drain, but do not hurry the pumping. Whatever is submerged in the flooded basement will not be damaged further. By delaying the pumping, serious structural damage may be prevented.
- After water has been pumped from the basement, shovel out the mud and debris while it is still
moist. Hose down walls to remove as much silt as possible before it dries.
- Floors and walls may need sanitizing, particularly if sewage has entered the basement. Scrub walls and floors with one of these sanitizing solutions:
- Chloride of lime (25 percent available chlorine). Dissolve a 12-ounce can in 2 gallons of water.
- High test hypochlorate (65 percent available chlorine) Stir 5 ounces into 2 gallons of water.
- Oil stains in basements caused by overturned or damaged oil tanks may be a problem following
flooding.
- Commercial products (such as Neutrodal ) will help neutralize fuel oil.
- Products are available in powder form or an aerosol spray for hard-to-reach places.
- To remove oil stains and destroy odor, wipe up excess oil, shake or spray product on the spot
according to manufacturer's directions, and let it set.
- Check supporting columns, beams, walls and floors. Structural damage to flooded basements usually includes buckled walls, settled walls or heaved floors.
- Buckled walls are evidenced by horizontal cracking and walls moving out of plumb. When this
condition is minor, you need not repair the wall immediately. However, any noticeably buckled wall will eventually collapse from normal ground pressures and seasonal temperature changes. When buckling has seriously weakened the wall, rebuild the damaged parts immediately. Build pilaster into walls over 15 feet long for reinforcement. Pilaster spacing should be 12 to 15 feet.
- Settled walls and footings are indicated by vertical cracks either in small areas or throughout the
structure. Repairs are difficult without special equipment. Contact a reliable contractor for this work.
- Heaved floors are those that have not returned to their original level, or have cracked badly. You may
need to construct a new floor:
- Remove old, broken concrete.
- Place 6 inches of gravel fill on the basement floor surface.
- Cover area with a polyethylene vapor barrier.
- Lay a 4-inch concrete floor with water proof expansion joints between the floor and the walls.
- The floor should be reinforced with steel. Welded wire reinforcement placed at mid-height in the slab is minimum reinforcement.
- If a floor is badly cracked, but has returned to its original level, and if there is sufficient headroom, place a new floor over the old one. Add a vapor barrier between the two floors. The new floor should be at least 2 inches thick.
- In houses without basements, the area below the floor may be completely filled with mud. Remove the mud as soon as possible to avoid rotting joists or foundation wood. Jack up the house, if necessary, to make sure all mud is removed.
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