Installation of Imitation Slate -- Brookline Builders
Imitation slate must be installed carefully following the manufactures instructions or the manufacture will not give you a warranty. Most imitation slate manufactures offer at least a 50 year material warranty, but if the new imitation slate tiles aren't installed exactly as specified in the installation manual, you will be on your own if the shingles fail.
Did you know that most old existing slate roof's were installed over roof sheathing made out of random width boards that were not tongue and grooved? In order to meet most manufactures specifications, the imitation slate shingles will not be warranted if installed over this type of sheathing. Don't be caught by surprise. If you go into your attic and can see that there are gap's wider than 1/4 inch between the sheathing it will be nessary to install 7/16" OSB or 1/2" plywood over the existing sheathing. This will make sure the nails grip the sheathing properly when installing your new imitation slate roof.
The nails spec'd for proper installation are very expensive, not your common galvanized roofing nail. These nails are ring shanked stainless steel. These nails will still be holding strong even after 50 or more years as stainless doesn't rust and the ring shank will keep them from pulling out. Standard roofing nails cost around $30 - $50 per case, these manufacture spec'd nails will cost close to $300.00 per case.
There are several installation patterns and styles available. Some manufactures offer up to three different widths for their imitation slate tiles. Although a random look may look very nice as a finished product, the installation of this random style requires more labor. Remember, the more random the pattern, the more labor and thus a higher cost for the installation. You can check out the EcoStar installation instructions here.