rejoint
to fill up the joints of, as stones in buildings when the mortar has been dislodged by age and the action of the weather.
rejoint: remortar old masonry between stones
Rejointing is the process of raking out failed mortar from between stones or bricks and replacing it with fresh mortar. Over time, mortar joints deteriorate through freeze-thaw cycles, moisture penetration, and simply weathering away; when this happens, water enters the wall assembly and can damage the masonry units themselves, the interior finishes, or the structural integrity of the wall. Rejointing stops this damage before it spreads.
The work begins by carefully removing the old, loose mortar to a depth of about 2.5 to 3 times the width of the joint, usually 25 mm to 50 mm deep depending on joint width. This is done with hand tools (cold chisel and hammer) or mechanical equipment (oscillating saws or grinders) without damaging the surrounding stones. The joint must be clean of dust and debris, and is usually dampened before new mortar is packed in.
The new mortar used in rejointing should match the original as closely as possible in composition, strength, and appearance. Using mortar that is too strong, for example, can cause damage to softer historic stones. The mortar is pressed firmly into the joint with a pointing trowel, worked to match the original joint profile (flush, raked, weathered, or recessed). Modern practice often specifies lime-based mortars for historic work rather than pure cement, which can trap moisture and cause harm.
Rejoint is labour intensive and is often the most visible maintenance cost on old buildings. Poor execution, such as using the wrong mortar type, failing to compact properly, or rushing the curing process, often leads to further failure within a few years. The term originated from the action of creating new joints, though it has come to mean specifically the remaking of existing ones.