New Bathroom Drain question

[militaryman]

Hi and thanks for taking the time to read my question. I want to convert a garage to include a bathroom. Currently it has W/D hookups. The house is a rambler on a slab but the garage is attached at a 90 degree angle to the main rambler (side entry) The existing toilets in the house which I assume are in line with the main drain from the road are about 10-12 ft from where the toilet would be located in the new garage (converting to bedroom suite) bathroom.

My question is.... Since I need a 3" drain for toilet can I put the toilet in the corner of "garage" close to existing house and tie into the main drain by going directly outside with the new plumbing drain and tie into the main drain before it enters the house?

Please see Picture schematic with descriptions below

http://picasaweb.google.com/107647753099808695953/Public#5559077644978662354

 

[Mr_David]

I don't see any reason why you couldn't.
Are the garage and house elevation pretty much the same.
Garages are usually lower.
If it is not drastically lower, then the sewer at point of connection should be plenty deep enough.
Don't assume the line goes straight out. Have it located.

 

[militaryman]

Yes, the garage is about 6 inches lower than the house slab -- Was hoping the main would be at least 28 inches deep which should give enough drop. I am thinking I have to start at about 18" right under the toilet to be below frostline and then need to drop 1/4" for each foot so that would be about another 3"

Since the garage is more level with the actual ground I would think the toilet flange would be sitting at ground level and if the main drain is at least 22 inches deep under ground level then i should have enough drop... ?

 

[Plbgbear]

I have to agree with Mr David. You need to locate your line outside and determine the depth before you do any work. The depth of your main line outside will determine everything. It's not uncommon for the sewer lines to be shallow depending on where the plumbing inside the house was started. Good luck