Stacked Plumbing

Cache

Let me see if I can provide enough background to get a good answer to this question. First the question;

Is there really a significant savings in stacking (concentrating) the plumbing of a house?

The background;
Designing a 4000sqft house, 2 stories above ground with a full daylight basement. Picture a 35'x35' square south facing floorplan, with a 25'x25' side entry garage attached to the east side of the home with a 400sqft guest suite over the garage. Georgian Colonial.

Easiest design of the house puts plumbing in the following locations:

• Kitchen in north-east corner of main floor sharing wall with garage.
• Laundry in utility room in garage but shares wall with the main floor, 10' south of kitchen.
• 1/2 bath located in center of west wall on main floor.
• Master Bath directly over kitchen on top floor.
• Shared full bath centered on top floor south wall.
• Guest suite bath in east gable of garage roof directly over garage doors (25' away from the master bath).
• Basement bath can really go anywhere.

If I tried to stack the plumbing, it would look more like this:

• Kitchen and Master Bath in north-east corner still on main and top floor respectively. No change.
• W/D utility room moved north 10-15' to share wall with kitchen, but still in the garage.
• 1/2 bath located just east of direct center of main floor.
• Shared full bath located on top floor directly over 1/2 bath on main floor (across hall from master bath).
• That hallway leads into guest suite in garage trusses where the bathroom would be moved to the west garage wall, requiring the bath to be split. Tub/toilet sharing wall with master bath. Sink vanity across hall sharing wall with shared bath.

So where I would otherwise have bathrooms on opposite ends of the house I would now be able to concentrate, and in some cases stack, the plumbing. Is there significant benefit in doing this, or are the savings relatively minor. Concentrating the plumbing makes the design harder and creates a bit more wasted space.

MechanicalDVR

The only real saving is the pipe cost. So if you can live with having to walk the length of the house everytime you wanna take a leak, go for it.

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KillerToiletSpider

Stacking it requires a lot less pipe, and probably will eliminate a roof penetration. Depending on code in your area, the price difference could be large. Stacking it makes for a little less labor also.

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RopeaGoat

Stacking will also allow for quicker HOT water to your kitchens and baths. With the houses getting more spread out we spend many callbacks installing recirculating lines/pumps. So many I've started leaving off a stub to make my job easier. This is where I especially like the ProPex piping system.

Just my $.02.
Also allows for homeruns and manifold/Aquacenter.

Cache

I guess my next question is more semantics. What exactly constitutes stacked? Toilets are obviously the big issue as running supply lines and waste pipes for a bathroom sink are cheap and easy. For toilets to be "stacked" are we saying that they either need to be directly above/below one another, or on exactly opposing points of the same wall? Or simply within close proximity to each other.

It seems safe to assume that toilets within close proximity would have no problem with soil pipes connecting to the same stack. My question is at what distance can a soil pipe no longer connect to the same stack and subsequently require an additional stack. Seems to me that needing a second soil/vent stack would pose the greatest cost increase? Given the information provided above is it likely that I would be able to connect all soil/vent pipes into the same stack regardless of layout, or will multiple stacks/vents be required? If I concentrated the layout the furthest toilet from the stack would be 10', but it would be closer to 35' if I didn't concentrate the layout.

Cache

Yeah, my brother just re-plumbed his old home with PEX homerun system. Completed all as a DIY project a couple years ago and it works great.

KillerToiletSpider

I don't know where you are at, so I don't know your code, here you are allowed 20% of all waste pipe in horizontal vent, so basically if the bathrooms are 35' apart, you are going to have to run a separate vent stack, wheres if the bathrooms are back to back, or close to that, you can use a single vent stack using branches off the waste stack.

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A flush is better than a full house.

Cache

Thanks for the help. I'm in Utah. I've been looking around and some houses have only 1 vent on the roof, and some seem to have more than 5. I don't really like the look of that many vent pipes on the roof, so I'm gonna try to keep everything close together. I finshed re-locating a couple rooms on the design last night and I think the layout will work ok. Still gonna have to check code to see how much horizontal vent I'm allowed though.

thom

If you're using plastic dwv pipe the cost of spreading out your plumbing vs stacking is minimal. CI is different. As said earlier, the real issue is getting hot water to the fixtures.

You have the same issues with HVAC, getting the conditioned air to the rooms efficiently. Centrally locating the furnace and water heater will improve efficiency and lower long term costs. These are much more significant cost issues than stacking dwv.

PARA1

The shortest distance between two points is a straight line in the opposite direction.--Bill Murry--CADDYSHACK