I'm adding a laundry closet (for stackable washer dryer) off my main entry hallway. The closet will push out into my garage. The interior wall I'm penetrating for the laundry closet door is load bearing, and the house is built on a slab. The garage slab is 4" lower than my house slab. I'm going to tie the drain line into the main waste line for the house, which is 15 (interior) feet away. I'll use a concrete saw to cut a trench through the concrete slab, but I'm not sure of the best way to run the drain line through the load bearing concrete foundation that separates the garage from the house. Any suggestions would be greatly appreciated.

Thanks:)

(Contractor) Are you sure this wall is load bearing. Note: not all exterior walls are load bearing walls if its on the side of the house unless its two stories or more. Even if there is a second floor find out which way the upper floor joist go. If they run parallel to your wall knock out it not load bearing. Iam a little confused here your just bumping the end wall of the house into the garage? If so make sure the new opening is double studded on its sides and a header on its top. If the knocked out wall is not bearing Just double plate the header. The concrete can be cut out for the plumbing with no worries even a bearing wall and conrete wall under can easily accept. A small concrete cut to put a 3 or 2 inch line in. Your bigest concern is the cut from your interior conc to the 25' tie in for slope. Min slope 1/4 fall per lineal foot. The bigest thing to think of is how are you going to vent this line so it actually drains well. It needs vented out the roof or exterior side wall. Set your washer drain height and measure down 28" for the stand pipe. Next a U bend at the bottom to trap sewer gas and then you head towards main.

Set your washer drain height and measure down 28" for the stand pipe. We do it a little differently here. We set our trap as close to the floor as we can and extend the standpipe up a few inches over the washers floor rim. This stand pipe should be a minimum of 36" to work effectively. Regards, Tom