Method and apparatus for applying mortar to underside of a building block

Apparatus for applying mortar to a side of a building block to be laid which side faces downwardly when the mortar is applied as well as when the building block is laid, wherein said apparatus comprises a rotary coating roller having a peripheral surface, a part of which is adapted to dip into a supply of mortar, said coating roller being operative to convey the mortar upwardly and to press the mortar against the underside of the building block such that first and second side edge strip portions of said downwardly facing side remain mortar-free, said apparatus further comprising means for producing a forward movement of the building block, said coating roller having an axis of rotation which extends at least substantially perpendicularly to the direction of the forward movement of the building block, and said apparatus also comprising first and second rows of free-running support and guide rollers, said rows being disposed in at least substantially mutually parallel relationship and being arranged at a spacing from each other transversely to the direction of the forward movement of the building block, said support and guide rollers being adapted to support said building block during its forward movement only with the side edge strip portions of the downwardly facing side of the building block.