I’ve discovered a rotten rim joist and several ends of floor joists when R&R an entrance door. I suspected as much since the floor was slightly sunken inside the home. The failure occurred since the mudsill is essentially below grade, nothing was really done in terms of moisture barrier and the lumber was not PTL. Furthermore, a concrete slab walk up to the door was poured directly against the foil-backed polyiso- insulation board that was placed against the foundation block. The joists are 2×10 and are above the slab only 4″ putting the mudsill at approximately 6″ down.
So, the questions are:
– How can I detail this better to prevent it from happening again aside from PTL and something similar to ice guard used on roofs. I dont’ know the product’s name but I used it for around windows to flash the rough sill rather fabricating a metal tray.
– I might be inclined to add a french drain while the slab is gone (expecting to demo it and replace to gain access to the rim joist).
– There may be still another source of the water intrusion since the subfloor was rotted out, too, and I believe that’s too high for ground water to have rotted it by capilary action through the joists at the contact point. That’s another issue since I’m sure the water primarily came in from the ground. The worst area is at the door where the slab is but there is further evidence several feet away where the earth and mulch are up against the house.