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damp floors / overhang soffit

Interior problem likely result of an exterior problem...

The hardwood floor in our living room has recently been getting damp after heavy rains, but only in a limited area under the dog bed. It is not wet dog or dog urine, as only the floor and underside of the bed is wet. The living room is on the upper floor, which is cantilevered out by about two feet - and is vented much like a roof soffit. (this allows outside air into the space between the floor joists...)

We live near the pacific coast (~2 miles) in the San Francisco area. Recent storms have produced driving rain from the east, which would blast it directly onto the patio door and window near the damp area on the floor. The patio door and large floor-to-ceiling window near the damp area do not show any signs of leaking, and there seems to be no standing water or signs of water above the floor.

We've had similar weather since moving into this house and this is the first sign of the dampness. Any thoughts before I tear up the floor or ceiling below to investigate?

Re: damp floors / overhang soffit

this is a toughie without actually seeing it but here's my best guess. lack of adequate insulation. mixing warm and cool creates moisture. imagine a bathroom vent pipe running through an attic. when the damper on the fan is stuck open warm air rises and warms up the vent pipe in the attic and the cold attic air, in the cooler weather, makes the pipe sweat. same with an AC unit in an attic during the hot weather. hence, when your dog is sleeping he heats up his bed and the floor gets cooled at night. condensation forms between the warm bed and the cool floor. i can assure you that you don't have a leak and that's my best guess as to why.


Re: damp floors / overhang soffit

Thank you for the quick response. It is good to hear - temporarily while the weather is so exceedingly wet out, the dog's bed will be relocated.

Now the question in my mind...
Why do I want the airspace between the first and second floor (between the joists) to be open to the outside?

In two-story homes I've owned before that did not have an overhang, there were no vents allowing outside air to flow between the 2nd level floor and the 1st level ceiling. It actually seems this exposure would cause more problems than it would solve as in this example...

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