Saddest sight I saw in the `74 Brisbane flood was that of pianos, street after street of them, veneers peeling, strings rusting, all sitting out awaiting removal. One thing about floods. You can disinfect, replace the drywalls and carpeting, repaint the whole house, but on the next dull day, the mouldy smell starts coming out of the woodwork.
Hi, Berb, I think it has more to do with the flood silt which penetrates into the smallest crevice and is difficult to reach. Maybe it`s hygroscopic and moisture in the air on an overcast day triggers off decay. I know many jetted out their houses with fire hoses, disinfected and still were affected when the weather changed. Having part of a house affected by fire can cause lingering smells unless you paint the smoke-coated timbers with Silvafos (a silver metal-based paint)to bind the particles. Never saw that tried with flood damage.
In another life, I was a roofer and did insurance reports. When the big flood hit us and stayed up for a few days, folks toured round in boats to offer help and rubber-neck. Normally, roofs are described as being affected by wind, hail, tree-falling,etc. For the first time, I wrote into cause of damage: roof hit by speedboat.