The plaintiffs by this bill seek to compel the defendants (the Archambaults) to remove a portion of the Archambault house which encroaches on the plaintiffs’ land in Marshfield. The plaintiffs and the Archambaults own adjoining ocean-front lots. Both lots are registered (G. L. c. 185). Neither certificate of title shows the Archambault lot to have any rights in the plaintiffs’ lot.
The Archambaults’ predecessor in title obtained a *92building permit in 1946 and built a house partly on their own lot and partly on the plaintiffs’ lot, of which the total area is about 4,900 square feet. Each lot had a frontage of only fifty feet on the adjacent way. The encroachment contains 465 square feet, and the building extends fifteen feet, three inches, onto the plaintiffs’ lot, to a depth of thirty-one feet, four inches. The trial judge found that it will be expensive to remove the encroaching portion of the Archambaults’ building. He ruled (correctly, so far as appears from his subsidiary findings and from the small portion of the evidence which has been reported) that there had been established no estoppel of, or laches on the part of, the plaintiffs in seeking to have the encroachment removed. It appears from the evidence that the Archambaults bought their lot from one vendor and the plaintiffs on June 14, 1966, bought their lot from another vendor. The judge found no evidence of any permission by the owners of the plaintiffs’ lot for the encroachment. The encroachment was discovered on July 14, 1966, when the plaintiffs had a survey of their land made.1
A final decree ordered the removal of the encroachment. The Archambaults appealed. The judge adopted as his report of material facts the findings already summarized.
1. In Massachusetts a landowner is ordinarily entitled to mandatory equitable relief to compel removal of a structure significantly encroaching on his land, even though the encroachment was unintentional or negligent and the cost of removal is substantial in comparison to any injury suffered by the owner of the lot upon which the encroachment has taken place. Geragosian v. Union Realty Co. 289 Mass. 104, 108-110. Ferrone v. Rossi, 311 Mass. 591, 594-597. Blood v. Cohen, 330 Mass. 385, 388-389. Sheppard Envelope Co. v. Arcade Malleable *93Iron Co. 335 Mass. 180, 187-189. Ottavia v. Savarese, 338 Mass. 330, 336-337. Brink v. Summers, 352 Mass. 786. In rare cases, referred to in our decisions as “exceptional” (see the Ottavia case, supra, at 336), courts of equity have refused to grant a mandatory injunction and have left the plaintiff to his remedy of damages, “where the unlawful encroachment has been made innocently, and the cost of removal by the defendant would be greatly disproportionate to the injury to the plaintiff from its continuation, or where the substantial rights of the owner may be protected without recourse to an injunction, or where an injunction would be oppressive and inequitable. . . . Lynch v. Union Inst. for Sav. 159 Mass. 306. Gray v. Howell, 292 Mass. 400. Triulzi v. Costa, 296 Mass. 24, 28. But these are the exceptions. What is just and equitable in cases of this sort depends very much upon the particular facts and circumstances disclosed.” 2 2. We here are considering the remedies to be applied with respect to registered land. Such land is protected to a greater extent than other land from unrecorded and unregistered liens, prescriptive rights, encumbrances, and other burdens. See G. L. c. 185, §§ 1 (e), 46 (as amended through St. 1963, c. 242, § 2), 47, 53, 57, 58, 77, 112; Swaim, Crocker’s Notes on Common Forms (7th ed.), §§ 985-990, 991, 995; Davis, Mass. Conveyancers’ Handbook (2d ed.), §§ 125, 128-129; Partridge, Deeds, Mortgages and Easements, 233. See also St. George’s Church v. Primitive Methodist Church, 315 Mass. 202, 204-206; Goldstein v. Beal, 317 Mass. 750, 758-759; Park, Conveyancing, § 581 et seq. Adverse possession (c. 185, § 53) does not run against such land. To recognize the encumbrance created by the Archambaults’ en*94croachment would tend to “defeat the purpose of the land registration act.” See Goldstein v. Beal, supra, at 759.
3. The present record discloses no circumstances which would justify denial of a mandatory injunction for removal of an encroachment taking away over nine per cent (465/4900) of the plaintiffs’lot. The exceptions (see fn. 1, supra, and related text) to the general Massachusetts rule, hitherto recognized as sufficient to justify denial of mandatory relief, have related to much less significant invasions of a plaintiff’s land, or have involved circumstances not here present. The invasion of the plaintiff’s lot is substantial and not de minimis.3 Photographs and maps in evidence, portraying the encroachment, show that the intrusion of the Archambaults’ building on the plaintiffs’ small lot greatly increases the congestion of that lot. The plaintiffs were entitled to receive whatever was shown by the land registration certificate as belonging to their grantor, unencumbered by any unregistered prescriptive easement or encroachment.
4. The Massachusetts rule in cases like this is well established. There is no occasion for resort to cases from other jurisdictions.
Decree affirmed with costs of appeal.
The brief findings and the limited evidence designated for report to this court leave it wholly uncertain (a) what, if any, inspection the plaintiffs made before purchasing their present house and lot, and (b) how much, if at all, the location of the Archambaults’ building affected the price paid by the plaintiffs.
Such cases have been based upon estoppel (see Malinoski v. D. S. McGrath Inc. 283 Mass. 1, 10-11; Ferrone v. Rossi, 311 Mass. 591, 594-595); or on laches (see the Geragosian case, 289 Mass. 104, 109-110, where the earlier decisions are reviewed; cf. Westhampton Reservoir Recreation Corp. v. Hodder, 307 Mass. 288, 290-291) ; or on the trivial nature of the encroachment or injury (see Tramonte v. Colarusso, 256 Mass. 299, 301; cf. Goldstein v. Beal, 317 Mass. 750, 758). See Lynch v. Union Inst. for Sav. 159 Mass. 306, 308-310.
Our position avoids constitutional doubts (see Opinion of the Justices, 341 Mass. 760, 786) which might arise were we to allow the Archambaults, at their option and as a result of the trespass of their predecessor in title, to expropriate part of the plaintiffs’ land by essentially an informal exercise of private eminent domain. See Constitution of the Commonwealth, Declaration of Rights, art. 10 (as affected by art. 39 of the Amendments); Riverbank Improvement Co. v. Chadwick, 228 Mass. 242, 248. Cf. Machado v. Board of Pub. Works of Arlington, 321 Mass. 101, 103-104.