Creating natural looks for artificial rock formations by backyard pools

Construction
Cast concrete artificial rock waterfalls typically require a steel structure and a bond wire to meet building codes. To ensure proper drainage, the concrete pad should slope toward the pool and have a bond break at the pool shell. It is also recommended to have at least 102 mm (4 in.) of concrete on the pad. Construction of caves and artificial rock formations also necessitates concrete backfill. For added safety and versatility, the cast-concrete rocks can be pre-drilled with 9.5-mm (0.38-in.) threaded eye bolts, allowing the attachment of mesh or solid safety covers for pool closure during colder months.

Placement
When custom constructing these artificial rock projects, best practices suggest the installation’s base components should overhang the pool beam by 25.4 to 50.8 mm (1 to 2 in.) to minimize the risk of water seepage. While the base components and ledgers typically have a dripline, water might still run down the face of a rock. Commonly, the most popular artificial rock size measures
3 m (9.8 ft) in length and 1 m (3.3 ft) in height, with an approximate 2.2-m (7.2-ft) wide “cave area” positioned 0.5 m (1.7 ft) above the pool’s waterline.

Handholds
If the artificial rock formation is placed in an area of the pool with water depth exceeding 1.2 m (4 ft), building codes usually require the installation of a “handhold.” To achieve this, the rock formation can be set back from the beam by about 51 to 76.2 mm (2 to 3 in.), and the beam must slope toward the pool to prevent seepage. In such cases, a 228.6-mm (9-in.) coping is often used to extend the rock into the pool and create the handhold.

Mortar techniques
Modern concrete castings are quite dense and do not readily absorb water, necessitating the use of a rich mortar mix for setting. High-quality mortar mix or cement can be found at most home improvement stores, which can be blended with masonry sand. It is crucial to ensure the mortar is easy to trowel into place, striking the right balance between being too runny or too stiff. Mortar beds should be 25.4 mm (1 in.) or more for base pieces and less for smaller rocks. For optimal bonding, mortar can be scrubbed to the underside of the rock. After application, the mortar should be allowed to set, and once hardened, it can be cut and brushed away. Some installers may use antiquing or rainbow cement for the mortar to achieve a desired aged or consistent colour look.