Thanks so much for thinking metal. As you do your research and due diligence, please also be sure to check into such things as the type of coating, the type of panel being installed, the warranty on the product, and the workmanship warranty. Best practice, whether battens are used or not, would call for underlayment even over old shingles. Successful installations can be made direct to deck or over battens. The airspace created by battens is a thermal break that can enhance energy efficiency. Battens though can make the roof harder to walk and perhaps more prone to wind uplift. If your attic is properly vented to code requirements, I can't think of a compelling reason for using battens. Of course in any event, any soft or rotted decking should be replaced. Feel free to contact me direct at todd@asktoddmiller.com if you wish.
I am hearing from one contractor ( with very good reviews in Google ) that he will be installing metal over the existing shingles directly with screws and another( no reviews ) says he will be installing wooden frames over existing shingles and metal will be screwed in to the wood , I am not clear which is the right way to go about it ; cost wise both are same ! Both doesn’t do any underlay! Any suggestions ?
