WE are building wood shed for fire wood. I have lined it with osb board does it need a sealer or paint it is inside of shed. Thank-you

If you want the shed to last a lot longer I would use a good grade of outdoor primer then outdoor paint on the inside.

Its unheated and will be subject to everything the outside will be except for direct sunlight.

I agree with smoothy.

U could also use a waterproofing stain. Only need one good coat.

Chuck