Help! New downstairs toilet

[Pete48]

Hi. Could you guys give me some advice regarding the following please? My wife and I are looking to move home and have found a property we really like. However, it has no downstairs toilet and we were wondering about the possibility of installing one in a partitioned section of the attached garage. The plan would be to put a door from the living room into a small storage room which, in turn would have a door into a toilet with washbasin.
I've actually modified the estate agent's floor plan which can be found here ..
Toilet Plan.pdf
Would the soil pipe be ok running along the garage floor? Would it need to be buried? Is this plan actually feasible? The work would be done by tradesmen, but I was wondering if you could give me a "heads-up" as we need some ideas before making an offer.
Thanks in anticipation!
Pete

 

[denso13]

Most things are doable, but you'll also need building regs approval. Drainage/vent positions, water, lighting, ventilation, floor level and construction methods are some of the considerations.

 

[Murdochcat]

The drains, not shown, will determine the costs and anything under ground can be expensive

 

[Old Salt]

Where is the current bathroom? Showing the upstairs layout may help.