Roughness gives propagules somewhere to catch and shelters them from rain, wind, or waves. Open porosity holds water after the surface has dried. On a facade panel, formwork milled from a simulation of runoff channels water to the zones meant to grow and leaves the rest to dry (BiotA Lab). On a marine tile, 3D-printed moulds cast crevices sized to the body of a specific intertidal species, so that a limpet or a juvenile oyster fits and a predator does not (Reef Design Lab). In both cases the geometry attracts colonisation, and nothing is planted.

Fresh Portland cement has a surface pH above 12, which almost nothing tolerates, and it takes years of carbonation to fall. Magnesium phosphate cement sets near pH 8 to 9, and on samples of it algae and moss established while ordinary concrete beside them stayed bare (Manso, 2014). For marine work, admixtures that adjust the chemistry of a standard concrete mix are sold alongside textured moulds, so the pH shift can be specified without changing the binder (ECOncrete). In practice, lowering the surface pH has a larger effect on colonisation than surface texture.

On a facade, water is the limiting resource. The Poikilohydric Living Walls project chose its organisms accordingly: mosses and lichens are poikilohydric, meaning they dry out fully and revive when wet, so a wall can go weeks without rain. Other designs layer an absorbent backing behind the concrete or thicken the panel to store water. The alternative, irrigation, is what makes conventional green walls expensive. Bioreceptive design tries to store and route water in the material itself so that irrigation is unnecessary.

Two forms have reached market: a bioreceptive concrete layer that is applied to an existing wall and seeded with moss (Respyre), and cast panels installed as prototypes in London (Cruz and Beckett, 2016). Retaining walls, noise barriers, and bridge abutments are the likelier targets, since they are large and rarely subject to aesthetic requirements. A retaining wall that carries lichen for a kilometre functions as a habitat corridor, which is one form more-than-human infrastructure can take. Claims for stormwater retention, particulate capture, and surface cooling are plausible but so far thinly measured.

About half of Sydney Harbour's shoreline is artificial, and a flat seawall supports far fewer species than the rocky shore it replaced. Living Seawalls (2018) bolts cast habitat panels onto existing walls, each patterned as a rock pool, a crevice field, or a honeycomb, and monitoring has recorded roughly a third more species on the panels than on plain concrete within the first years. Comparable admixtures and textured forms are now in ports and breakwaters in Europe, Asia, and the Americas (ECOncrete). The seawall keeps its structural function and gains an ecological one.