Shingles advice surprising

In a recent column I read: ''For years the shingle bureau has frowned upon any overtreatment of wood shakes and shingles other than at the factory.'' This is news to me as we have had our shingles oiled with linseed several times since the house was built in 1970, believing that this procedure is necessary.

I would appreciate your sending me the address of the Red Cedar Shingle & Handsplit Shake Bureau mentioned for further information on this subject.

Mrs. Penelope Tittmann Reno, Nev.

(Ed. note: Contact Marshall R. Ritchie, Red Cedar Shingle & Handsplit Shake Bureau, Suite 275, 515 116th Avenue, N.E., Bellevue, Wash. 98004. Phone: (206) 453-1323. I'd appreciate a copy of Mr. Ritchie's response.)