We live in Southern Michigan on a canal. Our house has a three sided glass enclosured sunroom. The access from the house into the sunroom is through a patio sliding glass door. One half of the sill of the Patio Sliding glass (that leads into the sunroom from the house) door is damp all the time. This dampness also seems to be on the lower courses of the brick. Again this problem is inside of the sunroom We can not locate a leak any where. There are no water marks on the higher part of the wall so the dampness does not appear to be coming from the roof. There is carpet in the sunroom and it does not seem damp (have done the paper towel squish test, no dampness detected) by the patio door. Next step is to pull back the carpet to check the slab position to the house. Do you have ANY other suggestions for me? I am at my wits end with this situation and know that there must be a fix to it but I can’t figure it out.