Larger cover plates normally are sealed with a gasket and bolted tight. Homeowners might consider doing this with a tube of sealant and a handful of nails. Consideration also needs to be given to basement floors when floodproofing. Water pressure under the flood can buckle the floor upward and possibly lead to collapse of the structure. Techniques are available to deal with this.
Consideration also needs to be given to the possible entry of flood waters through sewer drains.
One way valves can be installed to prevent sewer backflow. These and numerous other potential problems suggest the need for assistance from a professional specializing in floodproofing in all but the simplest cases. Home Learning Center Page Index Wet Floodproofing Much of the damage done to a structure by flooding is due to the effect of water on walls and floors, insulation, heating and air conditioning ducts, motors for furnaces and other equipment, and the electrical system. The concept of this technique is to allow water to enter the structure but minimize the damage that is done and facilitate the clean up after the flood. In the case of business structures where bare concrete walls and floors already exist, it may be very worth while to at least raise the electrical system.