The housing discipline is a relatively new concept that appeared with the 2007. Right to Housing Act (Law no. 96/2007). This law provides a clear framework concerning the rights and obligations of the different parties interacting in the property market. It also establishes a series of rights and responsibilities for people who own a dwelling. The 2007 Right To Housing Act provides a framework for the parties involved in the housing market to understand what constitutes a 'decent' home. The law also establishes obligations for those who own the dwelling.

You will find the most relevant advice for buy and property for sale in Spain (Barcelona) .

Check the state of the dwelling
Paying attention to the age of the building, the condition of the facade and the general state of repair can help you find accommodation that is not only acceptable but also durable. The quality of woodwork, paving, heating, water supply, refuse collection and toilets is important. Natural light, low levels of noise pollution, thermal protection and cleanliness are key factors for comfort in your home. The size of a dwelling is measured by useful square metres or constructed square metres. Constructed square metres are about 15% greater than useful square metres. This difference is important when seeking accommodation.

Check ownership
The Property Registry is a property database where the properties and the persons related to them. – If you have found a property that seems very attractive but the first name and surnade of its owner do not mean that they are those of a person who could sell it to you, you have to carry out a research to know for sure that this person does not have any other first name and surnade. – Otherwise, if you wish to contact that owner, you must write him using his first name and surnade or you can go to one of its homes or buildings; then ask for an appointment and meet him (her).
Check the planning status
If you’re thinking of buying a property in Barcelona, whether it’s for permanent occupation or to let out (or both!), it’s important to know the dwelling’s planning status. This is because a dwelling's planning status will have a direct impact on what improvements you can make and how you plan to use the property in the future. There are a few documents that provide information on a property's planning status in Barcelona, and the best place to start when searching for these details is by being prepared. My goal here is to share with you what I have done when researching for my own properties, along with some suggestions on where to look for information.
New dwelling: charges and payments
In addition, when a house is being newly constructed, Charges must be assumed by the buyer, towards the builder. These charges include VAT and 10% of the price of the new housing. In order to be entitled to a return on investment in the event of a later sale of the property in Spain, social housing and public promotion housing remain exempt from payment of all of these charges. When you sell your house, or if it is damaged, you must take out an insurance policy that covers at least fortuitous events and force majeure and damage to third parties.
Second-hand housing: charges and payments
There are several tax reductions for the acquisition of shared-ownership properties, which are usually considered as owner-occupied, according to the criteria set out in article 11 of Act 107/2006, July 15. They distributed into acquisition with special reduction of 10% on the share acquired, provided that it is paid with 30% down payment. The remaining balance will be subject to interest at Euribor-1 month plus 3 percentage points until the total amount is payable. Reductions for large families: Those who have at their disposal a floor area of at least 80 square meters are entitled to increase the floor area for up to 20% of its value whenever they acquire an Eligible Property. Tax Stamp duty (AJD) at 0.1%

Conclusion
Before buying a flat, it is essential to make a thorough inspection. The value of a flat , like any other real estate, depends upon many different factors: The location (i.e. the proximity of the flat to shopping, transportation and workplaces). The age and condition of the building (major renovations sometimes necessitate an increase in the price of a flat). Traditions and fashions, i.e., what is popular at a particular time or in a particular culture. Before you buy any property in Barcelona you should know these basis legal parameters.