Most landowners are familiar with the concepts of encroachment, and easements. Another area of law pertinent to adjoining landowners, but perhaps less familiar, is that of lateral support and subjacent support. This article considers the basic law and some practical aspects to keep in mind.


Basic Law:

The law states, in part, at Cal. Civ. Code §832, that, “each coterminous owner is entitled to the lateral and subjacent support which his land receives from the adjoining land…”

Coterminous, or adjoining, landowners are those persons having the same or coincident boundaries.

Lateral support exists when the adjoining lands are side-by-side. It is the right of the land to be naturally upheld by its neighboring land(s) and supported against subsidence, i.e. slippage, cave-in or landslide.

Subjacent support exists when the adjoining lands are above and below. It is the right of surface land to be supported by the land beneath it against subsidence.


Lateral Support

A landowner is entitled by law to the lateral support of adjoining lands. This right to support is subject to the right of the owner of the adjoining lands to excavate his property for the purposes of construction and improvement. In other words, you have the right to lateral support from your neighbors’ lands, but your neighbors do have the right to excavate their land. Because their excavation could affect the lateral support to your land, the law has placed the following conditions upon excavation:


  1. A landowner must give reasonable notice to adjoining landowners (and owners of buildings or other structures on the adjoining lands) of how deep the excavation will be, and when it will begin. [Cal. Civ. Code §832(1)]
  2. Care and skill shall be used to preserve the adjoining land in its natural state, without regard to buildings or structures upon it. The excavating landowner is not required to support any buildings or structures on the adjoining land. As long as the adjoining land is supported, the excavating landowner shall not be liable for damage done to those buildings or structures because of the excavation, except as may be otherwise provided by law.
  3. If the excavation will be deeper than the walls or foundations of adjoining buildings or structures, and is so close that it might damage them, the excavating landowner must give the adjoining landowner at least 30 days to take protective steps. The excavating landowner must also grant the adjoining landowner access to his or her land for this purpose. The adjoining landowner may waive the 30 day window if he or she wishes.
  4. If the excavation will be deeper than 9’ feet at the point where the joint property line intersects the curb, and if the adjoining landowner has buildings or structures whose foundation is at least 9’ feet deep, the excavating landowner, if given permission to enter on his or her neighbor’s land, then has an obligation to protect his or her neighbor’s land and/or buildings from damage from the excavation. The excavating landowner will be liable for any damage done other than minor settlement cracks.


Lateral support is a common law right. It is an absolute right incident to the land itself. While this right relates to the land in its natural state, it does not mean that an excavating landowner is free from liability for damage just because his neighbor’s land has a building on it and is “altered” from its natural state. If damage occurs, it is the excavating landowner’s burden to prove that the weight of the neighbor’s building was the primary cause of the damage by applying additional downward pressure and contributed to the subsidence of the soil.

The provisions of Cal. Civ. Code §832 speak of adjoining lands, but it should be noted that the right to lateral support is not limited to coterminous lands. This right extends to property separated by intervening parcels owned by other people. A landowner whose property is damaged by an excavating landowner, even though their properties do not share a common boundary, may still sue for the removal of lateral support. Liability for removal of the support is based on negligence thus is similar in that respect to tort law.

Subjacent Support

As with lateral support, a surface landowner has the right, at common law, to have his or her land remain in its natural state without subsidence caused by the subsurface owner’s withdrawal of the subjacent support.

The withdrawal of subjacent support is an absolute liability, meaning the excavating landowner, if found liable for damage, is liable without regard to negligence. The damages awarded would not be altered in any way by a showing that the landowner did not intend to damage his neighbor’s property. The damage done is the damage awarded.

While Cal. Civ. Code §832 expressly provides for both lateral and subjacent support, the language of the statute in its entirety has been held to govern only lateral support for coterminous, surface landowners, and to excavations on the land, not beneath it. The rights to subjacent support are found in case law.


Rights and Remedies

With both lateral and subjacent support, the cause of action arises upon the subsidence of the land, not its excavation. In other words, a lawsuit may be brought only once the dirt has fallen. This does mean, though, that a landowner may bring a separate suit for each occurrence, even though there was only one excavation.

The landowner whose property is damaged by the excavation may sue. A landowner whose property is damaged by an excavation done during previous ownership also has the right to sue. Non-owners may bring claims, too. A lessee of property damaged by excavation may sue to recover the amount their rent as damages.

As for whom to name in the suit, both the excavating landowner and the contractor may be held jointly liable. It is unlawful for the landowner and the contractor to agree that the landowner be absolved from liability for damage done by the excavation. However, a bona fide successor-in-interest to a person who removed the lateral support is not liable for damage from the excavation. In other words, if Owner A excavated the land, but Owner B owns the property now, Owner B cannot be sued for the damage done. This is not necessarily true if the transfer was made for the purpose of avoiding the liability.

Most landowners should seek to prevent any damage from being done in the first place. A landowner seeking to prevent his or her neighbor from beginning excavation may seek an injunction by showing that irreparable damage would be done if the excavating neighbor is allowed to proceed. The courts have discretion to award monetary damages instead of barring the excavation. The monetary award is calculated on the diminution of value caused to the landowner by the excavation.



As the world becomes increasingly crowded with greater density of housing issues as to injuring adjacent landowners become increasingly prevalent. The best time to confront the issue is before the damage is done and that is true both for the landowner engaging in construction and with the adjoining parcel owners. Jointly obtaining experts to advise and issue recommendations as to how to avoid damage is an excellent practical method for minimizing damage and the often substantial remedial (and legal) costs that can be anticipated otherwise.

And if you are suffering damage, it is clear that you must obtain legal and expert advice as soon as possible to see if injunctive relief may be available or, if not, whether damages lie. Note that liability of subsequent landowners of the offending neighbor is not always a given so delaying seeking relief is seldom advisable. That said, litigation is not an enjoyable activity and if it becomes likely as necessary read our articles on American Litigation, Cost Benefit in Litigation and Buying Justice.