Have Wenco, aluminium clad wood, mostly double hung windows installed in a 10 yr old house in southern Michigan. I lived in this building (duplex) for the first 6 yrs, but is now a rental and experienced alot of damage from a recent tenant. I am trying to identify how the damage occured and possibly prevent it in the furture.
The unit is 1000 sq ft, 2 bdrms, 1 bath and great room (kit/din and liv rm). Have a large exhaust fan in bath and kit. exhaust hood to remove shower/cooking moisture. Heated w/ forced air nat. gas, 90+ furnace.
The interior of the windows, finished w/ stain and 2 coats of polyurethane, showed a large amount of moisture damage in the 2 bdrms and bay window casements. I am wondering if tenants attempted to close and lock windows, but failed to slide both sashes in the fully closed position so latch did not engage locks to pull closed tight. Or, didn't try to lock the windows, but merely slide them somewhat closed. This would of allowed dry, cold exterior air to have direct contact with warm, moist interior air and caused a great deal of condensation, which lead to the damage.
The bath window was damaged in three months time by this same tenant because, I believe, an interior wooden matchstick blind was not opened (rolled up), but left closed and the rolled wood material absorbed moisture, laying against the wood sash, like a wet washcloth. Sufficient interior air was not able to reach that area to dry it out.