Understanding potential weaknesses of roofing material also requires
knowledge of repair difficulties. Individual slates can be replaced
normally without major disruption to the rest of the roof, but
replacing flashing on a slate roof can require substantial
removal of surrounding slates.
If it is the substrate or a support material that has
deteriorated, many surface materials such as slate or tile can
be reused if handled care fully during the repair. Such problems
should be evaluated at the outset of any project to determine
if the roof can be effectively patched, or if it should be completely
Will the repairs be effective? Maintenance costs tend to multiply
once trouble starts. As the cost of labor escalates, repeated
repairs could soon equal the cost of a new roof.
The more durable the surface is initially, the easier it will
be to maintain. Some roofing materials such as slate are expensive
to install, but if top-quality slate and flashing are used, it
will last 40-60 years with minimal maintenance. Although the installation
cost of the roof will be high, low maintenance needs will make
the lifetime cost of the roof less expensive.