I definitely agree I'll need an expert on site to take a look, but was curious to see if anyone else faced something similar and worked around it

There's always a creative way to do this. Can you find a corner of a room below to hide a pipe and then cross in the basement? Is there a wall somewhere to do the same thing? Are you sure about joists? Usually capes have a bearing wall down the middle with joists spanning across the house.

I've been trying to think creatively about it, and searched and searched for available areas to run the pipe. I even mocked up some basic 3D models and floor plans to give folks a better understanding about how everything is laid out (please excuse some of the mislabeled areas).

Current Situation:

Remodeled with new shed dormer:

Another angle of the new dormer:

Original floorplan:

Remodeled floorplan:

Plumbing solution?:

I think the solution might sound crazy but as you can see from the floorplans, the existing upstairs bathroom is on the right is where the plumbing stack is, and I want to add a bathroom and walk in closet on the left from the reclaimed crawlspace on left via a shed dormer. But I just don't see anyway to go through all those 2'x6" joists in the floor, especially if I need to accomodate a 3" slope/drop. So, here's what I'm thinking, I run the plumbing UP from the new bathroom WITH the joists then hang a right at the stairwell wall. This way the plumbing is running along the outside of the wall (which can hopefully be extended the 3-4" required and covered with drywall, etc.), and then the pipe can go through the top stair/joist and connect with the existing plumbing stack.

There are a couple of oddities with this solution, because I still need to accomodate a 3" drop when traveling right, as well as an approx. 2" drop to travel up to the staircase. But I think this can be accomplished if the floors for the dormer are built-up approx. 6 inches! I'm not sure how realistic that is, but I don't mind having a little step between the main bedroom and the new bathroom/walk-in closet. And that extra height should allow the pipe to slope/drop the required height and avoid going through all those original joists.

There is still the problem of what to do when the pipe ends at the stairs. I'm thinking it might still need to go through at least 2 joists, but hopefully that's workable....? I also don't know if building up a 6" floor for the dormer is workable either....it seems like the support below would need to be significantly strengthened before it'd be able to support all this new weight?

So what do you think? Am I crazy?

Why are you trying to get to your other plumbing stack in the first place? What does your first floor look like? Is there are crawl space or basement?

Yes you're crazy. That's a recipe for all kinds of plumbing issues. Not to mention that your upstairs doesn't appear to meet current code requirements for habitable space and will need a complete gut redo of the whole second floor to do so. If that happens, the second bedroom goes away. It's too small. But it would make a nice bath.

If you want to focus on just the plumbing portion of the much larger issue, you hire a plumber to consult. If you want to focus on the big picture issues of the whole, you hire the architect. If you want the big picture costs of what is architecturally possible, you hire a builder to consult with the architect. If you want to see if you'll get this big expenditure back at resale, you talk to a real estate agent.

Or you jusg look at this house as your transitional home on your way to the bigger house hat you want. Everything is grandfathered in at the moment. That changes when you start a remodel.

If that happens, the second bedroom goes away. It's too small. But it would make a nice bath.

What second bedroom?

Thanks for the responses.

@bry911 There's only 1 plumbing stack on right side of the house. The downstairs bathroom is basically underneath the upstairs Bathroom. I figured I'd need to connect to it to add a new bathroom. No crawlspace though, no basement, foundation is concrete slab.

@GreenDesigns Are you saying the upstairs as-is doesn't meet code requirements!?! Please provide specific code, because if that were the case none of the houses in my neighborhood (roughly 500+) would either since all are basically the same (there's only 2 different layouts, see Canterbury Village in Concord,CA). All were built in the 50's, all have small bedrooms/bathrooms. Or maybe you're saying it's ok now due to it being grandfathered in but new construction would trigger a review or something? Lots of houses in my neighborhood have added various extensions though and many still have original small bedrooms/bathrooms.

It is doable but is it worth the expense? I did an addition above an existing sunroom on the opposite side of the house as all orginal plumbing. We tied it together at the exterior sewage line. We spent 70k for a 8x13 ft bath addition with just middle of the road finishes. New roof to tie old and new parts together, new drive and walk way after needing to join new and old sewer together, new sod, new windows, siding, insulation, proper water proofing for the shower, new heating and ac in new space in addition to all the usual bath costs. Are you in an area that supports these costs if not look at houses that already meet your needs.

Why not line up downstairs exterior wall with dormer wall? That's the way my house is. Then you might have some room in the bathroom. Can you go straight down with a new stack and go outside and around the house in a trench? Yes you'll have to bust through some concrete where you leave the house, but it beats the other solutions. Be careful you frame shed dormer correctly or your roof ridge will sag. The rafters you'll be cutting keep the ridge straight (and supported).

@roarah, thanks for the info. And the cost is obviously a big consideration. 70k doesn't sound bad to me, I'm thinking our cost will probably be minimum 85k. I got a quote a while back for a dormer addition, but not with a bathroom, and that was 40k, I figured a bathroom would basically double that. As for the area, we live in the SF Bay Area where houses are ridiculously expensive. I don't think the value added to the home would be equal to the cost, probably half that actually, but it would allow us more closet space (which is desperately needed) as well as our own bathroom.

@seabornman That's an option I considered, and is still a possibility, but I was thinking that creating a new stack would be much much more expensive than tying together with the existing stack, but I could be wrong there, maybe it's not too bad? Do you remember how much that cost? The one issue with aligning with the exterior wall is that we don't want to disrupt the roof line too much. All the houses in the neighborhood use 1 of 2 floor plans, the houses that use the other floor plans have dormers, shed dormers in many cases, in the front of the house that face the street (picture the revised floor plan I posted turned 90 degrees counter clockwise). Their dormers are kind inset from the edge of the roof, so my thinking was our house wouldn't look too out of place if we added it inset as well, it's just be on the left side. But it definitely might be worth it for the extra space, especially if the new plumbing stack costs aren't outrageous.

Btw, I searched for relevant codes and found the following:

R304.1 Minimum area. Every dwelling unit shall have at least one habitable room that shall have not less than 120 square feet (11 m2) of gross floor area.

R304.2 Other rooms. Other habitable rooms shall have a floor area of not less than 70 square feet (6.5 m2). Exception: Kitchens.

It also states: In typical houses, all living, sleeping, eating or cooking areas qualify as habitable spaces. Bathrooms, toilet rooms, closets, halls, storage or utility spaces aren’t defined as habitable, for any dwelling.

But anyway you slice it, even with the remodeled floorplan the upstairs certainly meets the minimum requirements. The master bedroom is a little over 120 sq ft, and the second bedroom is over 70 sq ft (approx 90 sq ft). Even if the master bedroom didn't quite meet 120 sq ft, other habital areas such as the downstairs living room is well over 120 sq ft, so it'd just need to exceed 70 sq ft, which it certainly does.

The only codes I could find regarding bathrooms were ceiling height (which wouldn't be an issue) and minimum distances between toilet, sink, shower and tub:

• A minimum space of 21 inches must be planned in front of lavatory, toilet, bidet, and tub.
• A minimum space of 24 inches must be planned in front of a shower entry.
• The minimum distance from the centerline of the lavatory to a wall is 15 inches.
• The minimum distance between a wall and the edge of a freestanding or wall-hung lavatory is 4 inches.
• The minimum interior shower size is 30x30 inches or 900 square inches, in which a disc 30 inches in diameter must fit.
• A minimum distance of 15 inches is required from the centerline of a toilet and/or bidet to any bath fixture, wall, or other obstacle.

I don't see a problem with meeting any of these (depending on size of tub or shower, toilet, sink, etc.), which is why the plumbing issue seems to be the sticking point to me.

Have no idea if this is feasible, but could you expand into the garage space on the right? I assume that's a garage.

Way off scale, but you get the idea:

@awm03, Thanks. Yes, it is or was a 1-car garage at one point. It was converted to a dining and living room years ago prior to us moving in (I'd say 50% of the houses in the area had their 1-car garages converted as well). The previous owners also built a nice 2-car detached garage in the back, but that is also why we can't really expand into the backyard much because it'd be building on our driveway. But yeah, a number of homes around our block of expanded in the same way you indicated. Some look ok, some look down-right ugly, inside I'm sure they're great though. Here's a few examples:

Ugly!

Looks ok:

This one is actually right across the street from the one above. Looks ok as well. They've done a number of expansions/additions including a huge one in the back, which you can kind of see.

Expanding that way is a possibility, but it'd also probably require us to relocate our air-conditioner/furnace and all the duct work as that's housed in the attic above the converted-garage, with the duct work spidering out to all the rooms from there (none of these houses had central heating and AC originally, and it's actually pretty impressive to see how they added the furnace/AC to heat/cool all the rooms in the house.) So I'm hoping that expanding the other way is not only more cost effective and easier but more aesthetically pleasing.

Why not just move the bathroom so it's by the existing stack? Move the new dormer wall out so it's over the outside wall below.

And your "crawl space" is just attic space. Crawl space is under a house.