A slate roof can be an attractive and classic way to set your home apart from others in your neighbourhood. Slate roofs can also be an excellent value in roofing, as they can last much longer than asphalt based roofing products such as shingles, and will resist weather with less maintenance required than sheet metal roofing or other materials. Starting a slate roof the right way is the key to installing a good looking and long lasting slate roof, and there are a number of steps that you should follow. Much like laying a course of bricks or building a foundation, any errors that you make in begining will be magnified by the time you get to the end of the project.
Install the proper side lap strips by holding them in place and hammering them in using a slate hammer. Side laps are the area where the sides of the starter course of slate tiles overlap the first complete row of regular slate tiles. Installing these side laps at an exact measurement of 3" is crucial to the proper fit and finishing of your slate roof. In addition, you must install the side laps correctly or water leaks and damage can occur rapidly after the first rainfall hits the new roof. This involves using a countersunk nail hole and ensuring that the nail fits perfectly on the countersunk hole and doesn't go in farther. If you have not installed the proper starting strip, you will have problems setting the side lap as well as with other portions of the roof project.
Lay a cant or shim strip. The first course of slates that you lay on the roof will not line up properly with the subsequent rows unless a cant or shim strip has been laid at the edge of the roof in order to angle these tiles correctly. If you do not install the shim strip of the same type of wood that was used to create the roof itself, usually plywood, under the first row of starter slates, you will experience issues with the proper alignment and angle of the slates further up the roof as you go.
Install the starter course of slates at the same time as the first course of slates. If you install the starter course, then begin to install the first course later, this delay can lead to alignment problems. To do this, you will need to first make a chalk outline on the roof where the slate pieces will go and then you will need to properly lay your slate along the outline you have made. The starter slates should be laid with the back side facing up so that the first course can be placed atop and lined up flush.