The laminiates in the kitchen has been removed and the subfloor has a top layer of chip board is now very soft and crumbles / rotted and undernealth is polysterne insulation and then concerete floor. Also, the bathroom floor the mdf has weakened or rotten due to leak from toilet and sink and also underneath the front of the bath tub I am looking to have the floor repair and lay vinyl on top. What would be a practical way to make the subfloor water resistant / proof ? what material to use? for each of the area? What tradesman should I look for do this work ?