The window sash is especially vulnerable to water damage. Moisture leakage on the outside of the window and condensation on the inside contribute to rot at the glass-wood interface. Joints in the sash frame are to be checked for looseness, particularly along the lower rail; a procedure is given for this repair. Putty and paint must also be examined. Soaking the sash with linseed oil makes the wood more water-repellent. Instructions are given for installing glass panes in the sash. -- AATA