Site engineers will fabricate on site and make sure installation is done to design drawings. Any alterations will be dealt with as soon as they arise. By law dry risers have to have fire engine access within 18m of the dry riser inlet box and have to be housed in a fire resistant shaft. In commercial properties this is usually under the staircase of a fire exit.
After completion of the installation the riser will be hydraulically pressure tested to the standard BS990/2006. A test certificate will be issued.