Surface-applied linings are considered to include linings that are sprayed, spin-cast, troweled or adhered to the interior surface of pipes, manholes, tunnels or chambers. In small pipes, such linings are possible through remote spraying or spin-casting technologies with the proper application control for high-build lining thicknesses. In larger pipes, tunnels, manholes, etc. linings also can be applied as panels or troweled onto the surface. Depending on the method and/or on structural requirements, reinforcement layers can be included in the lining application.
As elsewhere in the classification of renovation methods, distinction in terms of structural function is not used here to sub-divide surface-applied lining methods because many lining and coating systems can be designed or modified to provide the level of structural function required for a particular application.