San Diego, California
Irregular flagstone makes a beautiful patio and a stubborn engineering problem: the stones vary in shape and thickness, the joints run wide, and everything still has to sit dead level and stay put. At a private residence in San Diego, California, interior designer Kristyn Harvey wanted a backyard patio and pool deck in irregular flagstone that stayed flat, clean, and low-maintenance. Installed in 2025 across roughly 1,500 square feet, The Landscaping Company set the flagstone on a ROMEX system, TRASS BED, ADHESION ELUTRIANT, and ECOFINE, for a durable, permeable surface built without a full concrete pour.
PRODUCT SELECTION
The assembly used ROMEX TRASS BED as the base, ROMEX ADHESION ELUTRIANT as the bonding agent, and ROMEX ECOFINE as the grout, chosen for durability, permeability, and to reduce the concrete pour. Laid 1.5 inches thick over an open-graded base, TRASS BED gave the flagstone a stable, load-bearing, permeable bed that drains rather than trapping water, which matters around a pool. ADHESION ELUTRIANT bonded each irregular stone to the bed in a wet-on-wet connection, locking pieces of varying shape and thickness into one level plane. ROMEX ECOFINE, a resin jointing sand in a neutral tone, filled the wide flagstone joints with a bound fill that is power-washable, weed-resistant, and ant-resistant, exactly the low-maintenance grout the client wanted.
PROJECT LOCATION
The project is a private backyard in San Diego, California, where outdoor living runs year-round and a patio and pool deck get used almost daily. The Southern California climate is mild and dry with intense sun, so the priorities are less about frost and more about a surface that drains pool splash and the occasional heavy rain, resists weeds, and keeps ants out of the joints. A flagstone patio here is on display constantly, so it has to look clean and sit perfectly flat.
PROJECT NEEDS
Two things drove the work. First, the grout had to be genuinely low-maintenance: power-washable so the client could clean the surface without eroding the joints, and resistant to the weeds and ants that undermine loose-sand jointing. Second, the irregular flagstone had to be set and locked in place with no trip hazards or uneven spots, both for safety underfoot and because the patio carries site furnishings that need a stable, level, damage-free surface. Loose or rocking stones would fail on both counts.
PROJECT SOLUTION
The base was filled with ASTM No. 57 open-graded stone, then topped with a 1.5-inch layer of ROMEX TRASS BED to create a stable, permeable foundation. Each flagstone was bonded to the TRASS BED with ROMEX ADHESION ELUTRIANT, locking the irregular pieces into a single level plane with no rocking or high spots, safe underfoot and solid enough to carry furnishings without damage. ROMEX ECOFINE neutral grout filled every joint with a bound, stabilized fill that stands up to power washing and shuts out weeds and ants. The permeable buildup let the surface drain without a full concrete pour, and the finished patio and pool deck gave Kristyn a flat, clean, durable flagstone surface for years to come.
Backyard patio and pool deck in irregular flagstone
San Diego, California
2025
Kristyn Harvey
The Landscaping Company
Private
Residential
