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For years, landscape contractors have been using adhesive, not mortar, to build concrete-block retaining walls. Flexible and watertight, these adhesives are now in the tool kit of mason Mark McCullough, above—along with a caulk gun to squirt them out. He shares three fixes that work better without mortar.

Missing veneer Thin stone or brick can pop off foundations and walls if water seeps into the mortar. To reattach the veneer, use an instant-grab polyurethane construction adhesive, like SikaBond Ultimate Grab (about $8 per 10.1-oz. tube; Sika), which doesn’t need bracing. Fill in around the stone with a sealant that includes aggregate, so it looks like mortar.

Loose stair tread A concrete stairway can shift as it settles, loosening stones or bricks that cap the steps. Lift the loose brick or stone and squirt a generous amount of construction adhesive on its underside before reinstalling it. Let the bond cure three to five days before using the step.

Wobbly chimney cap For a topper that stays firm, bed the stainless-steel cap into adhesive on top of the chimney’s crown, then fasten it with masonry screws. If the crown around the cap is crumbly, remove any loose mortar and replace it first, sloping the sides away from the chimney.