As a matter of principle, a common wall may be constructed upon it. Indeed ‘Every co-owner may raise the height of a common wall, but he shall be liable for the expenses necessary – (a) for raising the height of the wall….’ (Article 414 of the Civil Code).

Notwithstanding so, when constructing over an existing common wall, it is essential to adhere to the principles of co-ownership as established under the Civil Code. The pertinent provisions are as follows:

‘491. Each of the co-owners is entitled to make use of the common property, provided-

(a) that the use be made according to the destination of the property as established by usage;

(b) that it be not made against the interest of the community, or in such a manner as to prevent the other co-owners from making use of the common property according to their rights.’

The phrase ‘… not made against the interest of the community, or in such a manner as to prevent the other co-owners from making use of the common property according to their rights’ provides limited flexibility regarding the use of existing common walls for increasing their height. It clearly establishes that a ‘common’ wall cannot be subjected to additional weight in such a manner that, should a neighboring co-owner choose to make a similar modification, they would find the structural strength of their portion of the wall compromised. Specifically, in the case of two neighbors, each co-owner is entitled to half of the wall’s load-bearing capacity. Consequently, any party seeking to increase the height of the common wall may only do so provided that at least half of the wall’s structural capacity remains available for the other co-owner’s potential use. Clearly, exceeding this limit infringes on the rights of the co-owner even though it does not necessarily compromise the stability of the structure for the time being.

Clearly, this principle applies equally to the foundations because as held by the Court of Appeal in Estelle Azzopardi Vella et vs Michael Muscat (17 March 2004), foundations under a common wall are deemed communal property, serving as structural support for all overlying parts of the property. Consequently, any innovation that diminishes the usability of the shared parts or overburdens their capacity beyond half their bearing strength constitutes an impermissible use of common property.

In practice, the architect responsible for the works must, therefore, assess the structural adequacy of the wall as well as the underlying foundations in order to certify that the proposed modifications will not exceed half the existing bearing strength of said wall and supporting foundations.

This is why it makes perfect sense to consider constructing a separate wall even though the Planning Authority will not raise the issue.