Fix Fault Sunbeam

the damp is at the both back corners and around the door think we have sorted out the door but how can we fix the walls if its all resealed and awning rails sealed what the chances of the walls drying ... more

I came to my caravan, after the winter break, and the floor on the kitchen side has dropped a little. It is an 1988 Lunar Sunbeam. Any ideas on repairs? Easy? Finacially viable?