Before having new gutters installed, a friend took a look at my roof and said basically it's in good shape, but there are a few nails that need to be hammered back in. He suggested that those spots be re-tarred under the shingle where the nails are hammered back in. The gutter installer said they could hammer in the nails, but then apply silicone in the spots. So my question is, which is better - applying tar or applying silicone. Somehow tar sounds better, but I really know very little on the subject and would appreciate any guidance. Thanks to all!