In this video you can clearly see that cavity wall insulation has restricted/blocked the sub floor ventilation and caused the floor to collapse because of extensive timber decay. If you have cavity wall insulation in your property along with a suspended timber floor you should check your sub floor air bricks.
This is such a common problem that I have to rectify for my clients. If you have a dry rot or wet rot issue in your sub floor void, you should also get the drains inspected for blockages, and defects, as this can also a cause for excess moisture issues. Sometimes when lifting the floorboards the floor doesn’t seem to be that wet, when in actual fact it is below the surface, or it could just be its the warmer months of the year. Subscribe to my YouTube channel as I will be posting an interesting video regarding sub floor decay caused by blocked and defective drains.