(dissenting, with whom Ireland and Sosman, JJ., join). This case presents a question of statutory interpretation: does G. L. c. 40A, § 6, first par., permit a homeowner, as a matter of right, to reconstruct or renovate his residence on a nonconforming (undersized) lot, in a manner that increases its living space, height, or footprint, where the improved structure would be in conformity with all dimensional requirements in the town’s zoning bylaw other than lot size? In other words, does such a reconstruction “increase the nonconforming nature” of the residence, thereby removing it from the special protections afforded single and two-family residential structures under the grandfathering or so-called second “except” clause of G. L. c. 40A, § 6, and requiring the homeowner to obtain a special permit to proceed?1 The answer to the question has important consequences for residents of established neighbor*864hoods across the Commonwealth with single- or two-family homes built on modest-sized lots (as permitted at the time of their construction) that have become nonconforming as a result of zoning changes that have increased the minimum lot sizes for residential development in those neighborhoods. The answer of the concurrence would seem to require a special permit for any improvement that increases the living space of a grandfathered residence. Because it is my view that this answer accords far too little weight to the language of the statute, the legislative policy underlying the relevant clause, and its practical implications, I respectfully dissent.
The zoning act, embodied in G. L. c. 40A, was substantially revised in 1975, St. 1975, c. 808, in the wake of the 1966 passage of art. 89 of the Amendments to the Massachusetts Constitution (home rule amendment). Prior to its passage, the zoning power belonged exclusively to the State, and could be exercised by municipalities only to the extent that State law permitted them to do so. Durand v. IDC Bellingham, LLC, 440 Mass. 45, 50 (2003), citing Board of Appeals of Hanover v. Housing Appeals Comm., 363 Mass. 339, 356-357 (1973). Through passage of the amendment, municipalities gained constitutional authority to exercise the police powers of the State, including the power to enact zoning ordinances, except in contravention of State law or other provisions of the Constitution. Durand v. IDC Bellingham, LLC, supra at 50, citing Board of Appeals of Hanover v. Housing Appeals Comm., supra at 358, 359.
Included in the zoning act of 1975, therefore, are a number of important statutory limitations on municipal power and protections for property owners, only one category of which concerns us here: the extensive protection afforded owners of single or two-family homes constructed and situated in accord with local ordinances or bylaws (zoning ordinances) in effect at the time the homes were built. Later enacted zoning ordinances have no effect on the continued use and occupancy of these residences. G. L. c. 40A, § 6, first par. (first sentence) (“a zoning ordinance or by-law shall not apply to structures or uses lawfully in exist*865ence or lawfully begun, or to a building or special permit issued before the first publication of notice of the public hearing on such ordinance or by-law”). While these homes may be deemed “nonconforming” (because they no longer conform in some respect to current local zoning requirements), they are not “illegal.” Indeed, local zoning ordinances do not even apply to the “alteration, reconstruction, extension or structural change” of such homes so long as those improvements do “not increase the[ir] nonconforming nature” (emphasis added). G. L. c. 40A, § 6, first par. (first sentence). This latter protection is unique to single- and two-family homes. See Rockwood v. Snow Inn Corp., 409 Mass. 361, 364 (1991).2
*866We have previously held that the nonconforming nature of a structure is increased if it is “intensified]” by the improvement or if the improvement creates an additional nonconformity. Id. In the present case, we deal only with the former circumstance. As to the latter, the town has a number of dimensional requirements for the construction of homes on lots (such as height and setbacks), and could indeed have (but has not) promulgated others such as “reasonable regulations concerning the bulk ... of structures and determining . . . open space, parking and building coverage requirements” (emphasis added). G. L. c. 40A, § 3, second par. These regulations affect the over-all size and configuration of homes in relationship to the size and configuration of their lots, and the density of development permitted in the neighborhood. It is undisputed that the reconstructed building would conform to these requirements.
So the issue we must decide is whether the increase in the size or footprint of a single- or two-family home, as a matter of law, intensifies the nature of its nonconformity when its only nonconformity is, and will continue to be, the size of its lot. I conclude that it does not. The nature of its nonconformity can be fairly described as a “ [conforming structure on [a] nonconforming lot,” as compared to a nonconforming structure on a conforming lot, a nonconforming structure on a nonconforming lot, or various other “nonconforming uses” of build*867ings or land. Report of the Department of Community Affairs Relative to Proposed Changes and Additions to the Zoning Enabling Act, 1972 House Doc. No. 5009 at 35 (DCA report).3 The zoning ordinance to which the lot fails to conform has nothing to do with the size or placement of the structure on it. A 2,400 square foot structure on an undersized lot is equally as nonconforming as a 1,200 square foot structure on the same size lot. It is lot size, not building size, that is at issue. The nature of the proposed home’s nonconformity will remain unchanged and unaffected by the proposed improvements. The home will be neither less nor more nonconforming.4
This conclusion is consistent with the approach taken by the Legislature, in the same section of G. L. c. 40A, toward the application of zoning changes that increase minimum lot size (or “frontage, width, yard, or depth requirements”) on lots for “single and two-family residential use” that were recorded as such but not yet built upon when the zoning changes took effect. *868G. L. c. 40A, § 6, fourth par. (first sentence). For these lots, undersized and nonconforming as they may be, the zoning changes largely do not apply.5 A home of any size (whether 2,400 or 1,200 square feet) can be built on such a lot so long as it complies with other dimensional requirements for such structures, such as height and building coverage limitations. It would be striking indeed to conclude that the Legislature intended that the owner of a nonconforming unimproved lot would have substantially greater protections and rights than a homeowner who might want to add a dormer to a Cape Cod style house, or to enclose a porch or a garage for the purpose of adding a family room, or otherwise to improve a residence that lies on a similarly nonconforming lot.
In concluding otherwise, the concurrence relies on a view of legislative intent drawn from what it describes as the “unanimity of [authoritative] opinion [that] the ultimate objectives of zoning would be furthered by the eventual elimination of non-conformities in most cases,” citing the DCA report that was used by the General Court as a resource in fashioning the 1975 zoning act. Ante at 859, citing DCA report, supra at 39. See note 3, supra. This is inconsistent with how the Legislature in fact acted to balance the interest in eliminating nonconformities with the rights of homeowners to improve their existing homes without the expense and uncertainty of obtaining special permits from local zoning boards.
The DCA report, while referencing the aforementioned “unanimity of opinion,” also noted the “increasing awareness that the assumption it is desirable to eliminate non-conforming uses may not always be valid.” Id. at 39, 43. In fashioning its legislative recommendations, the DCA report included a number of mechanisms directed at eliminating such uses, such as *869authorizing cities and towns to “amortiz[e]” nonconforming uses, to take nonconforming property by eminent domain, and to impose regulations to mitigate the effects of nonconforming uses and structures on their surroundings. Id. at 44, 45, 47. All of these proposals were rejected by the Legislature. The DCA report also proposed protecting the owners of nonconforming homes only to the extent of recognizing their right to “perform normal maintenance and repair on non-conforming structures.” Id. at 44. The narrowness of this protection was rejected by the Legislature as well. Instead, the Legislature added the second “except” clause to the first paragraph of § 6, an addition not recommended by the DCA and nonexistent in prior State zoning law. In so acting, the Legislature rejected the DCA report’s objective of “eventual elimination” of nonconforming residential housing, and instead sought to protect such housing by allowing homeowners to “alter[], reconstruct[], exten[d]” or “change” the structures of their homes. G. L. c. 40A, § 6, first par. (first sentence). That protection should not be eviscerated by requiring homeowners to convince local zoning authorities that a proposed home improvement, which does not itself involve any further violation of the zoning ordinance, also does not — in some subjective, aesthetic sense — make an existing nonconformity more unpleasant. This deliberate and pointed action on the part of the Legislature has not been afforded appropriate weight by the concurrence in its interpretation of the statute.6
The application of the concurrence’s reasoning is not without practical consequence to the multitude of citizens who own homes in cities or towns that, at some recent point, have attempted to limit growth by increasing minimum lot sizes, often *870dramatically. The need to secure findings or special permits through lengthy, costly, and discretionary local zoning processes for any improvement that might increase the living space or footprint of a home may put such improvements out of reach for many homeowners.7 Requiring homeowners to run such an administrative gauntlet impedes and burdens the upgrade of a large part of our housing stock, much of which (except perhaps along the water or on the island of Martha’s Vineyard) is relatively “affordable.” I can find no evidence to support the concurrence’s conclusion that the Legislature intended such a result. Rather, all the evidence suggests the contrary, and surely the plain words of the statutory exception do not dictate or require such an outcome. For these reasons, I would reverse the judgment of the Land Court.
Structures without this protection fall within the following provision of G. L. c. 40A, § 6, first par. (second sentence): “Pre-existing nonconforming structures or uses may be extended or altered, provided, that no such extension or alteration shall be permitted unless there is a finding by the permit granting authority or by the special permit granting authority designated by ordinance or by-law that such change, extension or alteration shall not be substantially more detrimental than the existing nonconforming use to the neighborhood.” Although the statute speaks only to a “finding” by either the permit granting authority or the special permit granting authority, cities and towns may enact local legislation to provide for a special permit process, with the requirement that a supermajority of the permit granting authority approve, to generate such a “finding.” Shrewsbury Edgemere Assocs. Ltd. Partnership v. Board of Appeals of Shrewsbury, 409 Mass. 317, 324 (1991).
As I would reverse the judgment of the Land Court on the ground that the second “except" clause of G. L. c. 40A, § 6, first par. (first sentence), is applicable to the plaintiffs’ proposal to reconstruct a home on their property, I would not reach the question whether there was a rational basis for the board’s denial of the special permit on the ground that the reconstruction would be *864“substantially more detrimental... to the neighborhood.” G. L. c. 40A, § 6, first par. (second sentence).
If zoning ordinances do not apply to the “alteration, reconstruction, extension or structural change” of these homes, no special permit ought to be necessary to proceed with such improvements. Insofar as an improvement requires a building permit, the building inspector must determine in the first instance whether the home is nonconforming and, if so, whether the proposed improvement would “increase” the “nature” of the nonconformity, such that the improvement would require the homeowner to obtain a finding or special permit from the local permit granting authority. See note 1, supra. Such determinations should be based on objective rather than subjective criteria in order to ensure that the rights protected in the State statute are not undermined in the municipalities where they were intended to apply. Decisions of the Appeals Court that adopt a contrary “framework,” ante at 858, relying on subjective assessments by local boards and, in effect, requiring the homeowner to secure some form of special permit for any improvement to a nonconforming structure are, in my view, inconsistent with the plain wording and purpose of the statute. See M. Bobrowski, Massachusetts Land Use and Planning Law § 6.06, at 200 (2d ed. 2002) (Bobrowski).
The Appeals Court has held that the proper arbiters of what constitutes an “increase [in] the nonconforming nature of [a] structure” are zoning boards of appeal, which should make the determination with some measure of localized judgment. See Goldhirsh v. McNear, 32 Mass. App. Ct. 455, 461 (1992) (“Whether the addition of a second level to the carriage house will intensify the nonconformity is a matter which must be determined by the board in the first instance. The fact that there will be no enlargement of the foundational footprint is but one factor to be considered in making the necessary determination or findings”); Willard v. Board of Appeals of Orleans, 25 Mass. App. Ct. 15, 21-22 (1987) (“We think [the clause] should be read as requiring a board of appeals to identify the particular respect or respects in which the existing structure does not conform to the requirements of the present by-law and then determine whether the proposed alteration or addition would intensify the existing nonconformities or result in additional ones. If the answer to that question is in the negative, the applicant will be entitled to the issuance of a special permit under the second ‘except’ clause .... Only if the answer to *866that question is in the affirmative will there be any occasion for consideration of the additional question [of detriment to the neighborhood]”).
The concurrence correctly but quietly rejects some of the Appeals Court’s flawed reading of the statute, by stating that the building inspector should make the initial determination of whether a proposed reconstruction increases the nonconforming nature of a structure. Ante at 858 n.8. See Bobrowski, supra at § 6.06, at 200 (Appeals Court “has jumped the gun in assigning this initial determination to the board of appeals. The first official to review an application to extend a nonconforming residential structure will be the building inspector or zoning administrator, and her review will be under the auspices of a building permit application, not an application for a special permit or finding”). Yet the concurrence fails to acknowledge the error in the rest of the “framework” that, in essence, requires the homeowner to establish the existence of the grandfathered right through a process akin to the special permit process from which the Legislature intended to exempt the owners of single-family and two-family residences through the second “except” clause. See id. (“Willard test should be read as prescribing an entitlement to a building permit, not a special permit or finding, where no intensification of the nonconformity would result”).
Following the passage of art. 89 of the Amendments to the Massachusetts Constitution (home rule amendment), the Legislature requested that the predecessor agency to the Department of Community Affairs (DCA) conduct an investigation and propose a redrafting of the zoning enabling act. Res. 1967, c. 141. In 1972, the DCA issued a comprehensive report offering criticisms of the zoning statute and a proposed “comprehensive revision” of G. L. c. 40A. Report of the Department of Community Affairs Relative to Proposed Changes and Additions to the Zoning Enabling Act, 1972 House Doc. No. 5009 at 7 (DCA report). The report is the “chief document in the legislative history of the Zoning Act.” Bobrowski, supra at § 2.03, at 38.
The concurrence asserts that allowing the reconstruction without a special permit “would permit a landowner to circumvent valid and useful minimum lot area requirements.” Ante at 861. The concurrence also suggests that the new structure will increase the density of the neighborhood and reduce the open space previously existing on the lot, contrary to the broadly shared interest “in the preservation of the unique quality of Martha’s Vineyard.” Id., quoting Johnson v. Edgartown, 425 Mass. 117, 124 (1997). While minimum lot area requirements are indeed “valid and useful” in the way the concurrence details, it is unclear how the plaintiffs’ proposal seeks to “circumvent” those requirements. I do not question the legitimacy of minimum lot requirements as a means of preserving open space or of limiting the density of residential neighborhoods on Martha’s Vineyard, but I do not understand how the replacement of one single-family home with another single-family home, which complies as a structure with all zoning requirements, including height limitations and mandatory setbacks, increases neighborhood density or diminishes open space in a way contrary to Edgartown’s zoning bylaw.
General Laws c. 40A, § 6, fourth par. (first sentence), provides: “Any increase in area, frontage, width, yard, or depth requirements of a zoning ordinance or by-law shall not apply to a lot for single and two-family residential use which at the time of recording or endorsement, whichever occurs sooner was not held in common ownership with any adjoining land, conformed to then existing requirements and had less than the proposed requirement but at least five thousand square feet of area and fifty feet of frontage.” If a lot is held in common ownership with adjacent lots, other provisions apply. G. L. c. 40A, § 6, fourth par. (second sentence).
The concurrence advances the alternative argument that the second “except” clause provides no protection for the plaintiffs at all, because it speaks only to nonconforming structures or uses and not conforming structures on nonconforming lots. Ante at 861-862. As the concurrence firmly rejects such an interpretation of the clause, the argument is a poor response to the plaintiffs’ claim that the clause protects their proposal as a reconstruction that does not “increase the nonconforming nature” of the structure. The nature of the nonconformity of the plaintiffs’ house is its location on a nonconforming lot, and it is my view, as well as the view of the concurring Justices, see ante at 861, that the clause applies to such “nonconforming structures.”
The concurrence insists that the “rule does not, as a practical matter, make it more costly and difficult to modernize older homes.” Ante at 860. Yet the concurring Justices would hold that only those homeowners who opt to make changes to structures that “retain[] the size of the original,” may proceed with those changes without obtaining a special permit. Id. The special permit process without question renders many home improvements more costly and subject to the discretionary determinations of local zoning boards of appeals, which are apparently charged in considering special permit applications with promoting “conformity” and the prevention of “land use anomalies.” Ante at 861.