Garden room over sewer - base question.

[shippers88]

We are planning to have a garden room installed of around 6ft x 10ft that will go over a (private) sewer line in our back garden. It will be of timber construction, the glorified shed type, and likely be on top of dense blocks on MOT type 1, or an ecobase with shingle.
Would it be heavy enough to cause issues to the drain that passes through the middle below?

 

[motorbiking]

Do you know how deep it is?

 

[shippers88]

Around 1m - 1.2m.

 

[motorbiking]

Any reason you don't want a concrete base? Would give you peace of mind as the load would be spread across the base.