Plaintiffs seek a declaratory judgment establishing the extent of the burden imposed upon their property under the terms of a written instrument which subjects that property to a stairway easement in favor of defendants. The only uncertainty relates to the duration of the easement which is created by the following language: “. . . the stairway on Main Street then and now used for the purposes of ingress and egress to and from the properties hereinbefore mentioned, and fronting on Main Street of Stockton, California, should be kept and maintained as a stairway for the use of all properties hereinbefore mentioned ... so long as the Lot on which said stairway is now built is occupied by the building on said Lot, of which building said stairway forms a part.” The property involved consists of two adjoining buildings, each two stories in height, built in 1905. The principal means of access to the second floor of the building on defendants’ property, however, has been provided under the terms of the stairway easement by the stairway in plaintiffs’ building. Plaintiffs allege that the building upon their property is obsolete and that they desire to destroy their building, together with the stairway, and to erect a modern building thereon. The trial court rendered a declaratory judgment decreeing that plaintiffs’ title should be quieted against the defendants “as to the use of said or any stairway upon said premises above described as belonging to said plaintiffs in the event of the removal or destruction of the building now located thereon, whether by voluntary act of plaintiffs or otherwise ...”
The judgment of the trial court should be affirmed. The right to use a stairway on the property of another constitutes a grant in the nature of an easement. The easement, however, is in the building rather than in the land upon which the building is located. Thus, it is held that the destruction of the building in which the stairway is located also extinguishes the easement since there is no longer a servient tenement in existence upon which the right can operate. (Cohen v. Adolph *24Kutner Co., 177 Cal. 592 [171 Pac. 424, L. R. A. 1918D, 410]; Muzio v. Erickson, 41 Cal. App. 413 [182 Pac. 974]; Civil Code, §811 (2) Brechet v. Johnson Hardware Co., 139 Minn. 436 [166 N. W. 1070, L. R. A. 1918D, 691]; Shirley v. Crabb, 138 Ind. 200 [37 N. E. 130, 46 Am. St. Rep. 376]; Rudderham v. Emery Bros., 46 R. I. 171 [125 Atl. 291, 34 A. L. R. 602]; 9 Cal. Jur. 959; 19 C. J. 955; 17 Am. Jur. 1024; 2 Thompson, Real Property (1939), p. 362; 34 A. L. R. 606; (1918) 6 Cal. L. Rev. 299.) Citing many of the cases listed above, the majority opinion in this case concedes that the destruction of plaintiffs ’ building by natural forces would terminate defendants’ stairway easement by destroying the servient tenement. It is held, however, that this rule is operative only where the servient tenement is destroyed without the fault of the servient owner. The limitation thus placed upon the rule appears to me to be illogical. An easement of this kind requires both a dominant and a servient tenement and a complete destruction of the servient tenement destroys the easement because one of the requisite elements of such a property interest is lacking. (Cf. Bonney v. Greenwood, 96 Me. 335, 341 [52 Atl. 786]; Day v. Walden, 46 Mich. 575, 586 [10 N. W. 26]; Jones, Easements, p. 673, §838.) This is true even though the interest granted has been described as one which was to endure “forever.” (Cohen v. Kutner Co., supra.) The conclusion seems inescapable, therefore, that the grantee of a stairway easement who possesses merely a right measured by the existence of the particular structure has no property interest which survives the total destruction of the servient tenement, even though that destruction be accomplished by an act of the owner. (Civil Code, §811 (2).)
Most of the cases in which the courts have held that destruction of the building constituting the servient tenement extinguishes the stairway easement have involved destruction by natural causes over which the servient owner had no control. (See, 34 A. L. R. 606.) But the question of a voluntary destruction of the servient tenement in a similar situation was presented to the court in Union National Bank of Lowell v. Nesmith, 238 Mass. 247 [130 N. E. 251]. In that case two adjoining buildings were erected in 1852 with a common entrance, stairways and landings. A successor in title to one of the buildings proposed to tear it down and erect a new one without making provision for the common entrance and stairways. The court held, in 1921, that this could be done, saying (p. 249): “Where there is an easement of way through a *25building as distinguished from such right upon and over land without reference to a structure thereon, the incorporeal hereditament is measured and limited by the existence of the structure in which it only can exist and be exercised; and the person owning the easement by the evident intent of the parties has no easement in the servient estate apart from the building. If the structure ceases to exist, the right ends as there is nothing upon which it can be exercised. ... In the opinion of the majority of the court, the easement is also lost when the building is destroyed by the intentional act of the owner of the servient estate. The person entitled to such right has no interest in the land as such ...” Very few cases have discussed the problem of voluntary destruction, and the question has not previously been passed upon in this state. Defendants rely upon certain language in Muzio v. Erickson, supra, as indicating that the rule is limited to destruction of the servient building without the fault of the owner, but the court in that case was dealing with an accidental destruction by fire and did not have in mind the specific problem here considered. Since, such an easement cannot exist without a servient tenement, I cannot agree with the conclusion that it would not be terminated by the voluntary destruction of the servient tenement.
Although it is true that the destruction of the servient tenement would terminate the stairway easement regardless of how the destruction was brought about, a declaration to that effect would not answer the main issue presented by plaintiffs in this action. Plaintiffs seek a declaration that they “may remove their building, including said stairway.” Plaintiffs desire to know, in other words, whether they may remove their building, thus terminating the stairway easement, without incurring liability to the owners of the dominant tenement. The answer to this question depends upon the intention of the parties as expressed in the written instrument providing for the easement. Assuming, under the principles set forth above, that the stairway easement would be terminated by any destruction of the servient structure, the easement owner might nevertheless be entitled to the aid of a court in preventing such destruction or in recovering damages where the destruction is in violation of the clear intention of the parties. In the present case the instrument provides that “the stairway on Main Street . . . should be kept and maintained as a stairway for the use of all the properties *26... so long as the Lot on which said stairway is now built is occupied by the building on said Lot, of which building said stairway forms a part.” This language in no way limits the power of the owner of the servient structure in dealing with his own property, nor does it suggest that he must maintain the building in its present form for any particular period of time. In the absence of a clear indication of the intent of the parties, it is impossible to imply, as suggested by defendants, that the parties intended the plaintiffs’ building to be maintained in its present form, despite changing circumstances, pending its destruction by natural causes. The imposition of affirmative duties upon an owner of land should result only from a clear expression of the intent of the parties, and should not be implied in the absence of such an expression. (See, Coulter v. Sausalito Bay Water Co., 122 Cal. App. 480, 494 [10 P. (2d) 780]; Civil Code, § 806.) The agreement itself does not indicate that any such obligation is imposed upon the owner of the servient building, and there are strong objections of policy to the creation of such an affirmative burden by implication. An implied obligation to maintain the building until its destruction by natural causes or by order of the public authorities might easily result in a situation where the building could neither be disposed of nor replaced for a considerable period of time, contrary to the settled policy against undue restrictions upon the free use and alienation of property. (See, Friesen v. City of Glendale, 209 Cal. 524, 529 [288 Pac. 1080]; 7 Cal. Jur. 733; 3 Tiffany, Real Property (1939), p. 474.)
Defendants, as disclosed in their cross-complaint, interpret the instrument creating the present easement in direct opposition to these fundamental principles. They seek a decree requiring that plaintiffs’ building be kept and maintained to provide a stairway for defendants’ building “so long as that portion of said Wolf Building . . . exists and until the same be destroyed without the fault of plaintiffs.” The majority opinion in effect adopts this position by decreeing that “without the consent of the appellants [defendants] . . . the easement shall continue until the building on lot five is destroyed or the easement becomes inoperative without the fault of the respondents [plaintiffs].” In support of this interpretation of the instrument defendants urge that the servient owner should not be permitted to destroy another’s vested property right by his own voluntary act. It is true that during the life of an easement the servient owner may not inter*27fere with the easement which he has granted. (See, 9 Cal. Jur. 953.) It is established, nevertheless, in the law of real property that, if the parties so intend, they may create an interest in real property which is determinable upon the happening of a stated event even though that event is dependent in some measure upon the volition of the one granting the interest. (Rest., Property, § 44, comment h; id., § 45, comments g, h, i; see, La Laguna Ranch Co. v. Dodge, 18 Cal. (2d) 132 [114 P. (2d) 351].) Language providing that a property interest shall endure “so long as” a specified condition exists, as in the present case, is ordinarily interpreted to create such a determinable interest. (See, Rest., Property, §44, Illus. 5-8.)
In view of the principles stated herein and the considerations of public policy involved, I do not believe that the easement in the present case should be interpreted to compel the maintenance of plaintiffs’ building in its present condition until it is destroyed by natural forces or by an act of the public authorities. The conclusion of the trial court in this case seems more reasonable. As the court said in Union National Bank of Lowell v. Nesmith, supra, page 249: “The parties did not intend to and did not create a right of any greater permanency in the use of the petitioner’s building than was assured by the character of the structure and the likelihood that the owner would not for a considerable time change the manner of the use of his premises. This is the reasonable construction of their rights.” (See, Cotting v. City of Boston, 201 Mass. 97 [87 N. E. 205]; 3 Tiffany, Real Property [3rd ed. 1939], p. 354.) This construction of the easement would not result in a mere illusory interest. (See, Conard, “Easement Novelties,” 30 Cal. L. Rev. 125, 139.) In this ease, for example, the arrangement made in 1911 has actually been carried out for over thirty years. Only by the complete destruction of the servient tenement could the voluntary act of the servient owner terminate the easement and, considering that both buildings were new at the time the servitude was created, such a drastic step was highly improbable for a considerable period.
For these reasons the judgment of the trial court which permitted plaintiffs to remove their building, thus terminating the easement, seems to me to declare the rights of the parties correctly. The judgment should be affirmed.
Edmonds, J., Traynor, J., concurred.