You can find most of the DIN code ruling those structures in the Schmitt treaty on construction.

In Spain most of the masonry codes derive from a precode made by the Instituto Eduardo Torroja de la Construcción y del Cemento, PIET-70:Obras de Fábrica one of the nice things of which was the complete generality of applicability to every kind of masonry imaginable, even earthworks. More serious than this sounds.

It evolved unto MV-201 and then other later very similar codes in content.

A book on its application to concrete blocks (but as said entirely applicable as method for brick is

Fábrica de Bloques de Hormigón
Universidad Politécnica de Valencia, Servicio de Publicaciones, Libro-Apunte nº 72.

The current code in Spain is CTE that has a chapter on masonry structures. It may be less adequate to investigate your case because implementation of modern specs and details for masonries.

http://www.codigotecnico.org/fileadmin/Ficheros_CTE/Documentos/CTEabr09/DB%20SE-AE%20abril%202009.pdf
http://www.codigotecnico.org/fileadmin/Ficheros_CTE/Documentos/CTEabr09/DB%20SE%20abril%202009.pdf
http://www.codigotecnico.org/fileadmin/Ficheros_CTE/Documentos/CTEabr09/DB%20SE-F%20abril%202009.pdf


The Engineering Handbook, Dorf, the CRC Press, also has a nice and simple chapter on unreinforced masonry.

Do not forget to check the technical notes of this institution, there are many

http://www.brickinfo.org/pdfs/43G.pdf

and someone may be of direct application to your case.

Also,

http://www.thinkbrick.com.au/brick-data.cfm

has freely downloadable simple and modern info on these structures.

Best wishes

Someone (slideruleeara?) recently posted a link to old Kidder-Parker handbooks They have info on clay tile.

There is a clay tile handbook printed in the 50's that would be helpful if you can find one.

good luck.