I saw a webpage state that it is recommended to run the channel siding vertically (maybe because of the v groove on the non-showing side?) Anyways I have been told both, so I am wondering should the siding go up vertically or horizontally. It is the replacement on the south side of my home that wasn't kept up and gets little shade. I am looking for maximum life out of the replacement application so as little water penetration as possible is my goal. I also live on top of a hill, so at certain times during the year it gets really windy. Thanks again.