Laying Underground Gas And Water Pipes To Gas Boiler In Out House

Hope you can assist me with the following problem. I have decided to
secure my wall standing gas central heating system boiler in my
outhouse which is about 4 ft from the main house, instead on the
kitchen. When I lay the underground 28mm gas and 22mm water pipes to
connect this boiler to the new central heating circuit are there any
special requirement necessary for depth of trench to run the pipes or
lagging or any special piping materials for below ground.

Kindest regards, and many thanks in anticipation

mario wakeham