Adobe Has To Be Replastered Every Few Years

An adobe building is not permanent in the way masonry is. It stands because someone renews its surface regularly, and the schedule of that renewal is part of the architecture.

The wall is soil, and water is its enemy

Adobe bricks are sand, clay and straw dried in the sun, and they hold together through the clay binding rather than through any chemical set.

Rain running down an unprotected wall dissolves that binding and carries material away, so erosion begins immediately wherever the protective coat has failed.

The critical points are the base, where splash-back concentrates, and the parapet, where water sits, which is why those are the first areas to fail.

The plaster coat is sacrificial

A mud plaster applied over the bricks is intended to erode instead of the wall, and losing it gradually is the design working as intended.

Renewal means scraping back the damaged coat, mixing fresh material and applying it by hand, often with a float or with the hands themselves for the finish.

Because the plaster must move with the wall and let moisture out, it has to remain earthen, which is why cement stucco applied to adobe frequently causes damage.

Cement traps what earth releases

A hard, impermeable coat looks like an improvement and stops the annual work, and buildings treated that way often deteriorate behind the surface.

Moisture that enters through cracks or rises from the ground cannot evaporate through cement, so it accumulates in the adobe and softens it out of sight.

By the time the stucco cracks and falls, the wall behind it may have lost substantial material, which is the argument preservation specialists make against the shortcut.

Replastering is organized socially

The work is unskilled in the sense that many hands can do it and skilled in the sense that the mix and the finish require judgment.

At pueblo churches and community buildings, replastering is done by a group over a short period, with specific responsibilities held by particular families or groups.

That arrangement gets a large surface done quickly and also renews the relationship between the building and the people who maintain it.

The form follows the maintenance

Thick walls, deep window reveals, low buildings and generous roof overhangs all reduce the exposure that would otherwise have to be repaired.

Buttressed masses at corners and around doorways add material where erosion is worst, which is why the shapes soften and swell rather than staying crisp.

Buildings that imitate the look in other materials reproduce those forms without the reasons, which is visible in how differently they age.