In essense the vast majority of what makes Communities in Spain 'tick' is contained within the Horizontal Property Act. The Act was originally brought about in 1960 to cover the communal areas of blocks of apartments and flats. Without some sort of legal framework, communal areas were in peril of being neglected or only a handful of responsible owners paying for and taking part in their upkeep.

Communities may also decide to live by additional rules known as Statutes, which are in additon to but can never overrule or contradict the Horizontal Property Act. Anything in a Community's Statutes that does contradict the HPA is null and void.

The full version of the Horizontal Property Act is a useful document to get to know for anyone serious about their Community in Spain.

HORIZONTAL PROPERTY ACT (as amended)
Revised text of the Horizontal Property Act 49/1960, as amended by Reform Act 8/1999,
Civil Procedure Act 1/2000, and Equal Opportunities, Non-discrimination and Universal
Access for Persons with Disabilities Act 51/2003

PREAMBLE OF REFORM ACT (ACT 8/1999)
The extended period of time during which the Horizontal Property Act 49/1960, of 21st July, has been in force has evidenced its usefulness in a variety of fields, including the regulation of mutual relations between unit owners under this system of property ownership, real estate development and urban planning. With Act 2/1988, of 23rd February, and Act 3/1990, of 21st June, the Horizontal Property Act was adapted to social reality. However, the passing of time has created new social aspirations regarding the regulation of horizontal property.
At present, the unanimity rule is deemed excessively strict in as much as it hinders implementation of certain actions considered beneficial for property owners’ communities and even for society at large, for environmental or other reasons. Therefore, it seems appropriate to introduce some flex9ibility in the adoption of resolutions aimed at establishing certain services (such as janitor service, lifts, removal of architectural barriers impeding the mobility of people with physical handicaps, telecommunication services, collection and use of solar energy, etc.).
Another pressing social need is to enable property owners’ communities to legally recover
debts due by their own members. The reform aims at implementing the so-called “fight against defaulting” with a series of measures: creation of a reserve fund, inclusion in the deed of any outstanding debts, real attachment of the property transferred to payment of those general expenses attributable to the year when the transfer took place plus the preceding year, joint and several liability of the transferor who fails to report the transfer, enforceability of resolutions adopted by the general assembly and recorded in the minutes of its meetings, establishment of a rapid and effective civil procedure for the collection of debts to the community, etc.
This Act also includes an updated regulation of the recording of minutes of meetings, duties of the community’s governing bodies (particularly those of the administrator, whose position may be filled by any unit owner or by natural persons with adequate professional qualification), convening of meetings, exercise of voting rights, renunciation of the office of president and other matters encountered daily in community living and which were not sufficiently regulated.
With the above measures, the Horizontal Property Act gains not only flexibility and dynamism, but also effectiveness, adapting itself to the new social requirements so as to continue to be one of Spain’s most far-reaching legal norms.