An East Rock buyer sent me photos of a house whose listing said the brickwork had been “fully repointed last year.” The joints in the photo were flush, uniform, slightly glossy, and ran across the face of several bricks. That is not repointing. That is a skim coat, and it costs about a fifth as much.
What each one actually is
Repointing means cutting the deteriorated mortar out of the joints to a depth of at least two and a half times the joint width, cleaning the joint, and packing new mortar in, in layers, then tooling it to a profile. The new mortar is mechanically keyed into a clean, square recess and it is doing the same job the original did.
Skim coating — sometimes sold as “surface pointing,” “buttering,” or just as repointing by people who should know better — means smearing a thin layer of mortar over the existing joints and often over the brick faces. Nothing is cut out. The new material is a few millimeters thick, bonded to old crumbling mortar, and it will detach.
The skim coat looks better for two or three years. It is the more expensive option over any longer period, because the correct repair still has to be done afterward and now there is a layer of cement to remove first.
How to tell them apart on a wall
- Look at the brick edges. Repointed joints stop cleanly at the arris of each brick. Skimmed work laps onto the brick faces, and the joints look wider than they should.
- Look at joint width consistency. Real joints in an old wall vary because handmade brick varies. Perfectly uniform joints usually mean something was laid over the top.
- Scratch at a joint edge with a key. A skim coat is a thin shell over soft material and it will chip away to reveal crumbling mortar behind.
- Tap along the wall. Debonded skim sounds hollow.
- Check profile depth. Repointing leaves the mortar slightly recessed or flush with a tooled profile. Skim coats are usually proud of the face and have soft, rounded edges from being wiped rather than tooled.
Two other things that get sold as repointing
Grinding only the bed joints. Angle-grinding the horizontal joints is quick; the vertical head joints are awkward, so they get skipped and buttered instead. On a wall where only the beds have been properly done, water gets in through every head joint.
Pointing over paint or a previous cement job. A new mortar face over a hard old one has nothing to key into. It comes off in sheets, usually in the second winter.
What to ask before the work starts
Three questions settle most of it: to what depth are the joints being cut out and by what method; what is the mortar mix and how was it determined; and can they leave a mockup panel for approval before proceeding. A contractor doing real repointing will have ready answers. The specification points that ought to appear on the quote are listed in what an estimate should itemize, and the National Park Service preservation briefs at nps.gov are the reference most conservation specifiers work from.
For a price check: proper cut-and-point runs $14 to $35 per square foot at accessible heights in this region. Anyone quoting $4 to $7 is quoting a skim coat, whatever the paperwork calls it.
Frequently asked questions
Is a skim coat ever acceptable? As a deliberate, temporary weather seal on a wall awaiting a full repair, with everyone aware of what it is, occasionally. As a permanent repair sold at repointing prices, no.
The previous owner had this done. What now? Assess how well bonded it is. Where it is sound and the wall is dry, you can often leave it and monitor. Where it is drumming hollow or falling off, it should come off and the joints be done properly — budget the removal as an extra $10 to $25 per square foot on top of the repointing.
How long should real repointing last? Fifty years or more with the right mix on a wall with functioning gutters and flashings. A skim coat gives you three to eight. That difference is the entire economic argument, and it is why the cheaper quote is usually the more expensive decision.