Is it acceptable re-pointing to paste a thin over-lay of mortar over the original concave profile of a mortar joint?

Surface pointing, (also known as a “scrub joint” ) is commonly applied as a pasted joint with little depth of material. It is in fact the most common method of “repointing” a whole building but contributes very little. In fact many times this method accelerates deterioration by trapping water in the wall with high concentrations of Portland cement in the mix used.

Many masons utilize this method because pasting over the top of slightly recessed joints with a thin overlay goes up very quickly and gives the appearance of a lot of work received for what is a small amount of money charged for the work. In the end, the less than savvy building owner may think that since the entire wall has been “repointed” and now has a uniform look with all of the joints filled that they have received a good value.

What actually has happened is that the joint profile is not restored to a tooling within the edges of the brickwork but instead is a flat joint on the faces of the brickwork.

The fineness of Portland cement and fine play sand made in a 1:1 ratio with little or no lime content is often what is used to make this fine paste. The brittle, often gray Portland cement colored, scrub joint cracks and falls out within a few years.

Where the scrub joint does not fall out and was filled into deeper voids it only helps to keep moisture trapped in the bedding mortar. This allows any moisture in the wall to escape through the face of the masonry unit if it were to get out at all. A resulting “picture frame” of proud gray mortar remains with hollowed back masonry units as the final irreversible damage. “Tuck pointing” is what some inappropriately call the scrub joint. The scrub joint is very similar to grouting the face of tile although the scrub joint is applied course by course on the brick joints. The actual root of the name “Tuck pointing” comes from a narrow keyway cut into the center of a molded brick joint and then filled or “tucked” with a bright white, red or black lime putty to give a more formal and gauged appearance to the brickwork.

Prior to the tucking in of this lime putty a red color wash used to be applied first to the bricks and to the background mortar joints to give uniformity and aid as a shelter coat. Remnants of this color wash and infill of putty can be found on many historic brick buildings in the eastern states. The “grapevine joint” has taken the place for the name of a true ruled-key tuck pointed joint in my opinion. The grapevine joint is often reproduced in a restoration effort without the proper color wash and lime putty in-fill. This is a side note but shows that hastily going into repointing can result anywhere from improper working dynamics to a wholesale misinterpretation of the original design detail which alters the historic accuracy of the building in its setting.

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