P Trap Below Floor

I just recently stared doing a bathroom reno, and came up with my 1st problem. The previous owner had just had the whole bathroom wainscotted with subway tile(very nice and want to keep it), However I wand to replace the vanity he put in and put in a pedistal sink. he used an S trap because the sink drained to the floor. Now I know in Ontario S traps are not allowed and I don't want to mess with the tile on the wall to put a standard P trap. My question is can I put the trap below the floor, the basement under there isn't finished and will never be because it the furnace room. In ontaio the code states the distance from the sink to the trap can't be more than 900mm
(35.43"). As you can see by my dwg that I'm ok with that dim. However I know it's not the best solution but I think it's easiest one I have.

Also if it is ok can you check if the venting I'm going to do is ok as well. I think I'm wet venting the toilet, is this ok

I'm not a pro, but I'm quite sure you can't have a trap below the floor.

trap

The local codes will determine whether you can put the trap under the floor or not. Other than that, and the drawing being sideways, it appears to be proper.

Gary Swart said:

I'm not a pro, but I'm quite sure you can't have a trap below the floor.

Click to expand...

What about a shower or tub trap, there between floor and covered in most of the time.

It has to do with standpipe length.
Some codes only allow the standpipe to be so long to prevent siphoning.

The further the water can fall before it hits a trap, the faster it can go...it may have enough intertia to clear the trap on its own, leaving the trap dry.

this is what my building code gives, so I think I'm ok but i'm worried about siphoning to. Maybe if i put 2 45 degs it would help slow it down. What do you think

Individual opinions aside, in your case the tail piece length isn't a problem based on Ontario plumbing code. As HJ suggested earlier, you need to contact the local building inspector's office about locating the sink trap under the floor.

Speaking of opinions, unless Ontario is inhabited by giants, I don't see how you could allow for a 36" tailpiece and not expect the trap to be under the floor.

As long as the trap is vented properly, it shouldn't siphon.