In this case we revisit the holding of Wyoming Twp v Herweyer,1 and consider whether a municipality constitutionally may provide that mobile homes are to be sited only in mobile-home parks and exclude all mobile homes from other residential zones.
Robinson Township commenced this action against Donald and Merle Knoll, seeking removal of a mobile home from their 80-acre parcel of land.
Count I of the complaint alleged that the use of the mobile home was contrary to § 307.1 of the township’s zoning ordinance,2 which provides that mobile homes may be located only in mobile-home parks, and to § 1302.1 of the ordinance,3 which requires that a building permit be obtained before *309the erection of a building or structure on any property in the township. Count II alleged that because of violation of the same sections of the ordinance, the mobile home was a nuisance per se.
The answer raised affirmative defenses based on the unconstitutionality of the ordinance in that it arbitrarily and capriciously prohibits a proper land use, and is overbroad, failing to establish clear standards to be observed by property owners and citizens of the township.
Trial was had on stipulated facts, including: the home had been placed on the parcel; the parcel was not a mobile-home park; no building permit had been obtained; and the Knolls had dug a well, obtained a septic permit, applied for power from Consumers Power Company, cleared trees for a roadway and erected a rail fence around the site. No claim was made that the dwelling was not a mobile home within the meaning of the ordinance.
The trial judge, citing Wyoming Twp v Herweyer, held that "unless and until such decision is reversed”, the provision that mobile homes are permitted only in mobile-home parks was valid, and accordingly ordered removal within 30 days.
The Court of Appeals reasoned that because 1) there was no existing mobile-home park in the community, and — given the state of construction on a newly approved mobile-home park — "the use of land for mobile homes is neither imminent nor a factual certainty” and 2) "[a]s a matter of law”, "a single mobile home [is not] a nuisance per se or detrimental to public health, safety, morals or general welfare, either”, the township had totally excluded a legitimate use from the entire township.4 The Court found no justification for this *310total exclusion, and held the ordinance unconstitutional. The Court found its conclusion reinforced in that the Knolls’ land was so zoned that it could be licensed as a mobile-home park, commenting that "if the existence of such a park on that site poses no threat to 'public health, safety, morals or general welfare’, it is difficult to perceive how the existence of one mobile home could do so”.
We agree with the Court of Appeals that the ordinance is unconstitutional, but on other grounds.
We hold:
(1) The per se exclusion of mobile homes from all areas not designated as mobile-home parks has no reasonable basis under the police power, and is therefore unconstitutional.5
The reasoning on which the rule of Wyoming Twp v Herweyer was based is no longer valid in light of improvements in the size, quality and appearance of mobile homes, and that decision and cases to the same effect are overruled as to housing that is not a "trailer”.
We add, however, that a municipality need not permit all mobile homes, regardless of size, appearance, quality of manufacture or manner of on-site installation, to be placed in all residential neighborhoods. A mobile home may be excluded if it fails to satisfy reasonable standards designed to assure favorable comparison of mobile homes with site-built housing which would be permitted on the site, and not merely because it is a mobile home.
The Robinson Township ordinance embodies a per se rule segregating mobile homes from residential zones that are not mobile-home parks, and is therefore unconstitutional.
(2) The complaint also alleged violation of the *311provision of the zoning ordinance relating to building permits. A building permit could not have issued because of the per se rule confining mobile homes to mobile-home parks. It necessarily would have been futile for the Knolls to apply for one. For this reason, the township is entitled to no relief based on the Knolls’ failure to apply for a building permit.
(3) We intimate no opinion whether building code provisions may now be invoked against the Knolls, leaving that question for consideration by the circuit court should the township seek further relief on that basis.
We vacate the judgment of the Court of Appeals, and remand to the circuit court for further proceedings not inconsistent with this opinion.
Municipalities throughout the state have assumed the continuing validity of the rule of Wyoming Twp v Herweyer in drafting their ordinances. We reserve the question whether our decision overruling that opinion as applied to housing other than "trailers” should be applied retroactively in other pending cases or to other ordinances and, if so, whether retroactivity should be conditioned upon compliance with reasonable standards designed to assure favorable comparison of the mobile home in question with site-built housing which would be permitted on the site.6
I
In Kropf v Sterling Heights7 this Court said *312that "[a] plaintiff-citizen may be denied substantive due process by the city or municipality by the enactment of legislation, in this case a zoning ordinance, which has, in the final analysis, no reasonable basis for its very existence”.
A "reasonable basis” must be grounded in the police power,8 which this Court has defined as including "protection of the safety, health, morals, prosperity, comfort, convenience and welfare of the public, or any substantial part of the public”.9
The township’s argument based on the land planning principle that like uses should be grouped and incompatible uses kept separate begs the question raised by the appeal: do mobile homes differ from other single-family dwellings in any constitutionally cognizable manner which would justify their per se classification as a different use? If not, then the ordinance limiting mobile homes to mobile-home parks has "no reasonable basis for its very existence”.
In Kropf, we reaffirmed the principle that " '[w]hile an ordinance must stand the test of reasonableness, the presumption is in favor of its validity and courts may not invalidate ordinances unless the constitutional objections thereto are supported by competent evidence or appear on their face’ ”.10
*313The Knolls, having failed to produce any evidence in the circuit court, can succeed only if the rule that no mobile home may be located outside a mobile-home park is invalid on its face.
We believe that it is.11
II
Wyoming Twp v Herweyer, holding that a municipality may constitutionally limit trailers to trailer parks, would seem to be dispositive of this case, and was so treated by the trial judge. We conclude, however, that it does not control.
That case, decided over 30 years ago, dealt with trailers. Today, we consider the per se exclusion not of trailers, but of mobile homes — and more than the label has changed with time. The mobile home today can compare favorably with site-built housing in size, safety and attractiveness. To be sure, mobile homes inferior in many respects to site-built homes continue to be manufactured. But the assumption that all mobile homes are different from all site-built homes with respect to criteria cognizable under the police power can no longer be accepted.
A
Section 203 of the township’s zoning ordinance defines "mobile home” as "[a] movable or portable dwelling constructed to be towed on its own chassis, connected to utilities and designed without a permanent foundation for year-round living as a single-family dwelling”.
If mobile homes are to be excluded from all residential zones in Robinson Township other than *314mobile-home parks, it cannot be because they are "movable or portable”. Site-built homes are "movable or portable”, although they are rarely moved.
We note in this regard that § 500.2 of the township’s building code12 specifically provides for the issuance of moving permits to allow the relocation of one- or two-family dwellings from outside the township or from another location within the township. Any dwelling covered by § 500.2 is, by the township’s definition, movable. It would be arbitrary to discriminate against mobile homes on that basis.
Nor do the criteria "constructed to be towed on its own chassis” and "designed without a permanent foundation” identify characteristics which justify the exclusion and segregation of mobile homes.
One can agree that a community has a legitimate interest in safeguarding residents against, for example, windstorm damage, justifying a requirement that a mobile home be firmly attached to a solid foundation on the site. And a municipality may reasonably conclude that a dwelling the wheels and chassis of which are exposed is un*315sightly or is likely to lead to transience and should not be tolerated alongside site-built homes. These and similar considerations would justify requirements that certain on-site modifications be made as a condition to placement of a mobile home in an area not a designated mobile-home park. The ordinance governing moving permits, discussed above, employs such a mechanism.13
The ordinance defining "mobile home”, however, reflects no such concerns. To say that a dwelling was "constructed to be towed on its own chassis” or "designed without a permanent foundation” speaks only to its origin and not to its present characteristics.
Just as "the reasonableness of a zoning restriction must be tested according to existing facts and conditions and not some condition which might exist in the future”,14 so must an ordinance restricting the placement of mobile homes be directed to the dwelling as it will exist on the land, *316and not, as here, to its characteristics when delivered to the site.
B
While the characteristics specified in the ordinance are not themselves a basis for the disparate treatment of mobile homes, they do serve to identify "the mobile home”. If that label implies the existence of other (but unspecified) characteristics which provide a basis for restricting mobile homes to mobile-home parks, there is a valid purpose for the ordinance.
We are unable to identify any inherent characteristics of mobile homes that justify the per se rule of the ordinance.
Amicus curiae Michigan Townships Association argues that the segregation of mobile homes is justified on aesthetic grounds.
It appears that mobile homes can be designed or modified to compare favorably in appearance to many site-built homes. There is no longer reason to presume that mobile homes will fail to live up to a community’s aesthetic standards. Reasonable requirements to assure favorable comparison with those standards, of course, can be imposed by a municipality.
Concerns based in health and safety are also illusory. A municipality, again, is free to deal with concerns of this type in a reasonable code. Standards to assure that mobile homes compare favorably to other housing in, for example, insulation, adequacy of plumbing, and size of the living space exist15 or can be imposed. And, as we have noted, a *317community may impose requirements to assure protection from windstorm damage.
Another concern that has been voiced is that mobile homes are given to transient use. The practical necessities attending the installation of a single mobile home in an area in which site-built housing is allowed, along with conditions (such as those discussed above) that a township might reasonably attach to such mobile-home use, vitiate this cause for concern. A parcel of land of sufficient size to meet community standards probably will have been purchased by the mobile-home owner. Utility lines may be installed to the site; the municipality may require that a foundation to which the home will be firmly attached be laid, and other on-site modifications may be made to bring the mobile home and the parcel on which it is located into conformity with community aesthetic standards. In light of the investment required to so install a mobile home as a single-family dwelling, it is unreasonable to assume the mobile-home dweller will stay only a short time.16
*318The disparate treatment of mobile homes seems to be based on attitudes which once had but no longer have a basis in fact:
"Community fear of blight can be traced to the low quality of both the early trailers and their parking facilities. Economic conditions of the 'thirties, followed by wartime housing shortages and rapid relocations of the labor force, pressed many thousands of unattractive trailers into permanent use. Often these units were without running water or sanitary facilities. There were no construction standards to insure even minimum protection against fire or collapse. They were parked in areas which were usually crowded, poorly equipped, and generally unsuited to residential use. As a result, conditions in these parks seldom exceeded minimum health and sanitation standards. The specter of such parks teeming with tiny trailers made community apprehension understandable. But substantial improvements in the quality of both mobile homes and park facilities may have undermined the bases for this antipathy today. The mobile home currently produced is an attractive, completely furnished, efficiently spacious dwelling for which national construction standards have been adopted and enforced by the manufacturers’ associations.”17_
*319Decisions from other jurisdictions, while not directly on point, support the view that per se discrimination against mobile homes can no longer be legitimized.
In holding that mobile homes intended to be used as permanent dwellings are taxable as real property, the New Jersey Supreme Court explained that "[t]he early house trailers, which originated a half century ago, have been described as makeshift contraptions 'not really fit for permanent human habitation.’ * * * That they were then viewed as personal property can have little relevance when dealing with modern mobile homes * * *. These modern homes not only have all of the facilities of conventional homes, including sewage, water, lighting, heating and air conditioning, but also are more and more being constructed to look like and be used as conventional homes”.18
The Nebraska Supreme Court, holding that mobile homes cannot be taxed as motor vehicles, observed that "[t]he evidence in this case discloses that the mobile homes in question resemble in all respects a residence. * * * The evidence in this record further discloses that the interiors of these mobile homes resemble a residence in every respect, and one looking at the exhibits disclosing the interior of these mobile homes, if not advised that in fact they were mobile homes, would not be able to distinguish them from any other residence”.19
The New Mexico Supreme Court recently held that the mobile home there in question was "substantially the same as a conventional one-family dwelling” and therefore "does not violate the let*320ter or the spirit” of a subdivision’s restrictive covenant prohibiting trailers.20 The description of that mobile home demonstrates that mobile homes are not inherently incapable of achieving the aesthetic and comfort standards of conventional dwellings: •
"Parker purchased two lots in the Deming Ranchettes subdivision in 1975 and 1977. He bought a double-wide mobile home and moved it on the lots. The wheels, axles, and running gear were removed and sold, and the home was placed on a concrete and slump stone foundation. The mobile home has three bedrooms, two full baths and contains 1,440 square feet of floor space. A patio, a 200 square foot porch, sidewalks, and a 672 square foot two-car garage were constructed. A water well was drilled and a septic tank was installed. Both were connected to the mobile home. A conventional style asbestos shingle roof and aluminum siding were added to the home. A garden was planted and 210 trees were obtained to be planted.
"Parker testified that he and his wife intended to reside in the home permanently. Photographs admitted into evidence showed that their home had the appearance of a conventional single-family dwelling. It compares favorably with other homes in the subdivision.”21
The legislatures of various states have provided that mobile homes may be taxed as real property,22 and one statute prohibits ordinances which, like Robinson Township’s, discriminate against mobile homes.23_
*321Moreover, Robinson Township’s building code allows for prefabricated housing which is assembled at the site.24 There can be no reasonable basis for distinguishing between mobile homes and other prefabricated dwellings. Both are "movable or portable”, and may be similar in appearance and constructed of similar materials. It is not a valid basis for distinction under the police power that one is not only prefabricated but also preassembled, and "constructed to be towed on its own chassis”.
This is not to say that a municipality must permit all mobile homes, regardless of size, appearance, quality of manufacture or manner of installation on the site, to be placed wherever site-built single-family homes have been built or are permitted to be built. Nor do we hold that a municipality may no longer provide for mobile-home parks. We hold only that a per se restriction is invalid; if a particular mobile home is excluded from areas other than mobile-home parks, it must be because it fails to satisfy standards designed to assure that the home will compare favorably with other housing that would be allowed on that site, and not merely because it is a mobile home.
*322We affirm the finding of the Court of Appeals that the ordinance is unconstitutional but vacate its judgment and remand to the circuit court for further proceedings not inconsistent with this opinion. No costs, a public question.
Kavanagh, Williams, and Fitzgerald, JJ., concurred with Levin, J.Wyoming Twp v Herweyer, 321 Mich 611; 33 NW2d 93 (1948).
“Mobile Homes — Where Permitted: Mobile homes are considered as dwelling units and are not permitted as an accessory use to a permitted principal use and are permitted only in approved mobile home parks.” Robinson Township Zoning Ordinance, § 307.1.
"Application. Except as otherwise provided, it shall be unlawful to erect any new building or structure or to alter any existing building or structure at a cost of $200.00 or more until a permit therefor has been obtained from the building inspector by the owner or his duly authorized agent. Application for a permit shall be in writing and upon duplicate printed forms furnished by the building inspector. Such permits shall be non-transferable and must be obtained before any work, excavation, erection, alteration, or movement is begun. Satisfactory evidence of ownership of the premises may be required by the building inspector and shall be furnished upon request. If the application is approved, the building inspector shall so mark both copies over his signature, shall file one copy in the office of the township clerk of Robinson Township, and return the other copy to the applicant together with a construction card signed by the building inspector stating the extent of the work authorized, which card shall be attached to and remain on the premises during the progress of the work authorized.” Id., § 1302.1.
Robinson Twp r Knoll, 70 Mich App 258, 264-266; 245 NW2d 709 (1976).
Const 1963, art 1, § 17.
This case was tried on a stipulation of facts. The record shows that the mobile home placed on the Knolls’ land is 14' X 70', and that some improvements have been made. There is no indication that this mobile home is of a kind that the township could exclude. Our decision, however, is not based on a determination that this mobile home could not constitutionally be excluded.
Kropf v Sterling Heights, 391 Mich 139, 157; 215 NW2d 179 (1974).
"The power of the city to enact ordinances is not absolute. It has been given power by the State of Michigan to zone and regulate land use within its boundaries so that the inherent police powers of the state may be more effectively implemented at the local level. But the state cannot confer upon the local unit of government that which it does not have. For the state itself to legislate in a manner that affects the individual right of its citizens, the state must show that it has a sufficient interest in protecting or implementing the common good, via its police powers, that such private interests must give way to this higher interest.” Id.
Cady v Detroit, 289 Mich 499, 504-505; 286 NW 805 (1939).
Kropf v Sterling Heights, supra, p 156, quoting Northwood Properties Co v Royal Oak City Inspector, 325 Mich 419, 423; 39 NW2d 25 (1949).
See fn 6.
The section provides in part:
"Moving Permit: Any person desiring to move any one- or two-family dwelling and/or accessory building from outside of the township limits to any location within the township or from one location to another location within the township shall file a written application for a moving permit with the Township Board of Appeals. Said application shall set forth the present location of said building and/or buildings, the location of [sic] which said building or buildings are proposed to be moved within the township, the age of the building or buildings, a statement as to whether or not the building or buildings comply with the requirements of the building code and if not what improvements applicant proposes to make to bring said building or buildings in compliance with the building code. The application shall be accompanied by a site map as required by Sec. 501.1 of the Building Code and said map shall clearly indicate front, side and rear yards as required by Sec. 501.2 of the Building Code.” Robinson Township Building Code, § 500.2.
"The Board of Appeals shall make or cause to be made an investigation in regard to such application, and if it be determined that the building and/or buildings complies with and is in conformity to the Robinson Township Building Code or will be brought into conformity with said code by the applicant and that such building and/or buildings at the proposed new location will not be injurious to the contiguous property and the surrounding neighborhood, the Board of Appeals may grant a moving permit, and if the applicant is required to make any improvements or changes to bring said building or buildings into conformity with the Building Code the permit shall specify such requirements. If any improvements or alterations in the amount of $200.00 or more are required, the applicant shall apply for and secure a permit for such alterations pursuant to this ordinance before moving said building and/or buildings under the moving permit issued by the Board of Appeals.
"The foundations and all other new portions, improvements or alterations to said building or buildings shall be constructed in conformity -with the Township Building Code and the use, location of said building or buildings and yard areas shall conform to the Robinson Township Zoning Ordinance and Building Code.” Id., § 500.2.
Christine Building Co v Troy, 367 Mich 508, 516; 116 NW2d 816 (1962).
See Department of Housing and Urban Development, Mobile Home Construction and Safety Standards, 24 CFR § 3280.
See A Comparison Between HUD’s Mobile Home Construction and Safety Standards (1975) and Building Officials and Code Administra*317tors (BOCA) Single Family Dwelling Code (1975), which is Appendix C in the brief of amicus curiae Manufactured Housing Institute, Inc.
"At their location [mobile homes] are removed from the axles and wheels and placed on concrete pads and piers each about 6 to 7 feet apart. In addition, with units constructed during the last 3 years, hurricane bands built into the walls of the units are anchored with bolts augered 3 to 4 feet into the ground.
"[0]nce put in place and made immobile, they are often skirted around their bases. According to plaintiffs’ witness, between 75 and 80 percent of mobile homes once located are never moved. When they are moved, it takes approximately three days to dismantle the mobile home and set it up for moving, and several more days to replace it in its new location. At present prices moving expenses will range from $500 for a single-wide, to $1000 for a double-wide.” Gates v Howell, 204 Neb 256, 262; 282 NW2d 22 (1979).
"It need hardly be pointed out that these double width homes are intended to remain on site permanently, and that their removal by cranes or other heavy machinery would undoubtedly entail considerable difficulty and oftentimes considerable damage to the landscape. Insofar as the single width homes are concerned their removal would also entail some difficulty since in their current models they may he *318as much as seventy feet long and fourteen feet wide. Here, as with the double width homes, the intent that they remain on site permanently is entirely evident.” Koester v Hunterdon County Board of Taxation, 79 NJ 381, 386; 399 A2d 656 (1979).
Transient use could be expected, if at all, only of mobile homes located in, rather than away from, mobile-home parks. But even this expectation is not supportable in fact, for "[w]hile mobile homes were originally for transient purposes, today about 60% of all mobile homeowners never move their home. The MHMA [Mobile Home Manufacturers’ Association] reports that the average stay in one location by mobile-home owners is 58 months, which is approximately the same residency duration as in conventional housing. About 70% of the mobile homes used since World War II have been used as permanent dwellings.” Neithercut, The Mobile Home: Problems With Its Recognition as a Valid Housing Source, Newsletter, Real Property Section, State Bar of Michigan (No 10, Dec, 1975), p 25.
Note, Toward an Equitable and Workable Program of Mobile Home Taxation, 71 Yale L J 702-703 (1962).
Koester v Hunterdon County Board of Taxation, supra, p 388.
Gates v Howell, supra, pp 262-263.
Heath v Parker, 93 NM 680, 682; 604 P2d 818 (1980). See, also, Hussey v Ray, 462 SW2d 45 (Tex Civ App, 1970); Manley v Draper, 44 Misc 2d 613; 254 NYS2d 739 (1963).
Heath v Parker, supra, pp 680-681.
See Neb Rev Stat 1978 Cum Supp, § 77-202.12, and statutes cited in Koester v Hunterdon County Board of Taxation, supra, pp 388-389.
In 1975, the Vermont Planning and Development Act was amended to provide that, subject to certain minor exceptions, "no zoning regulation shall have the effect of excluding mobile homes, *321modular housing, or other forms of prefabricated housing from the municipality, except upon the same terms and conditions as conventional housing is excluded”. Vt Stat Ann, tit 24, § 4406(4). Former Vt Stat Ann, tit 24, § 4407(11), which permitted a municipality to confine mobile homes to mobile-home parks, was repealed.
"Approval of Alternate Types of Construction and Materials.— The building inspector may approve the use of types of construction such as prefabricated houses or materials that vary from the specific requirements of this Code if, (1) such alternate types of construction or materials comply with the recommended standards of government agencies or other national organizations which publish recognized standards relative to building materials and workmanship, or, (2) reports of agencies or laboratories generally accepted as competent by engineering authorities indicate that alternate materials or construction equal or exceed the applicable Code requirements.” Robinson Township Building Code, § 102.