When composite slates fail, its likely to be in one of the following ways.

Curling:

A few of the thinner slates will curl if they're not pre-bent when they're installed. This can sometimes be corrected using double-sided tape.

Inadequate Headlap

Leaking is often caused by improper installation.
The headlap for composites is 3 inches minimum, which is the same as for stone slates. You may see 2-inch headlaps on roofs steeper than 12:12, but any slope less than that should have at least a 3-inch headlap.
Youll have no way of knowing during an inspection what the actual minimum headlap required by the manufacturer is, but if you see less than 3 inches, you should recommend evaluation by a qualified roofing contractor.

Excessive Brittleness

Many manufacturing companies that have closed created composites that became excessively brittle over time. After a while, the slates just cracked and fell apart.
Look before you walk!

Its crucial that you examine these roofs carefully before you try to walk them. Some types of failed composite roofs are impossible to walk without causing damage.  So, from a window, deck or ladder, check out composite slates closely before you step on them.

Failed Coatings

At least one company uses a coating to color their slates, and there have been some coating failures. Most manufacturers mix the pigments with the material so that the color goes clear through the tile.

Some types of solid, polymer-based composites can be walked as long as the sun is shining on them, but get very slippery as soon as the sun goes down. These tiles are typically smoother and stiffer than rubber composites that are safer to walk.

Da Vinci Composite Slate

Da Vinci is one of the most common brands of composite slate. Their installation will be similar to other brands.

Installation Instructions