Installed in 1996, this North Carolina brick patio began to come apart within 10 years. But what started out as a repair of a few loose bricks turned into a major replacement job, thanks to faulty installation details and poor drainage.
The original mortar was honeycombed with voids. When subjected to below-freezing temperatures, water trapped in the pockets froze and expanded, loosening the bricks and crumbling the mortar.
To compensate for the absence of expansion joints in the large slab, the author installed a Schluter-Ditra uncoupling membrane. The membrane--which is embedded in unmodified thinset mortar--allows for differential movement between the pavers and slab.
Modular pavers measure 7 5/8 inches by 3 5/8 inches and are designed to be laid out in 8-inch increments (with 3/8-inch mortar joints). Here, the author installs the first of two parallel columns of bricks, which he'll use as story poles as he lays the pavers in between them.
Here's a photo of the installed brick patio, with the layout lines superimposed on the photo. Note how the pattern is centered along both the length and width of the patio.
Because the brick pavers measured 1 3/8-in. thick (rather than the full 2-inch thickness of a standard brick), the author was able to use a smaller tile saw rather than his 14-inch brick saw to make most cuts.
Pavers should be fully supported by the mortar bed. Strings are used to keep the courses straight and the pattern true.
When the author taps or presses the brick into the mortar bed, he avoids using the handle of his trowel so that he doesn't sprinkle the face of the bricks with mortar and stain them. The torpedo level is handy for determining when the brick is even with its neighbor.
Grout mortar is mixed to the same proportions as setting bed mortar, but in a slightly drier mix. The author uses a margin trowel to spread it in a patty about ½-in. thick on his hawk. Tapping the handle of the hawk on a hard surface drives the mud onto the surface of the hawk and helps hold it in place.
The author cuts a ½-in. wide slice from the flattened mortar on the hawk, positions the slice over the joint, then pushes it into the joint with a small margin trowel.
After the mud on the hawk has been used up, the author packs the joints with his tuck pointers. It typically takes several passes of filling and packing before the grout joints are completely filled up.
After the grout joints are packed full and have set up a bit, the author goes back and dresses the joints with a concave jointer. Pressing hard against the jointer as it is run over the joints packs the mortar tight and gives the top of the joint a neat, concave profile.
After allowing the grout to harden for about a day, the author used a bucket trowel, which has the front half cut off square, to break off the fins on the joints, then swept up the crumbs of mortar.
Scotch-Brite scouring pads (green synthetic steel wool pads) and water was used to scrub the bricks around the edges. By working carefully and timing things right, the author was able to avoid the use of chemical cleaners.
After thoroughly rinsing the surface, the task of cleaning the bricks was complete, and the author was able to move onto the next section.
Expansion joints were needed wherever the paving abutted vertical surfaces. To keep mortar from squeezing into the ½-in. wide expansion joints in the field, the author inserted ¼-in. slats of wood wedged in place by shims.
Prior to caulking the expansion joints, the author installed foam backer to keep the sealant from sticking to the bottom of the joint. The top of the backer rod is recessed about 3/8-inch below the top of the joint, ensuring that the joint depth equalled the approximate width of the joint.