[WWPierre]

How do I determine what size sewer to install for a condo/commercial development? How many fixtures on what size pipe? Can I find a table on the internet? Many condos have more than one set of fixtures, is there a standard "plumbing fixtures per 1000 sq. ft." rule of thumb?

[massplumber2008]

Hi WWpierre:

Sorry... no 1000 sq. ft. rules here. All pipe sizes are determined by counting FIXTURE UNITS and then applying that total number to a chart that shows size of pipe needed.

Further, each state has its own tables to be used for horizontal and vertical waste pipe and vent sizing. You will be best advised to consult your local plumbing inspector and ask for the particular code book you guys are using in your area. He can probably copy off the table you need to determine your numbers.

As a general rule... tank type toilet is 4 fixture units (FU), lavatory is 1 FU, bathtub or shower is 2 FU, kitchen sink is 2 FU, dishwasher is 1 FU, and washing machine is 3 FU.

Here, you would add the fixture units together per condo. Then add all condo. Numbers together to get the final size pipe required. All buildings must have a 4" minimum sewer pipe into the building.

In my area, maximum FU on horizontal drain is 34 FU for 3" pipe and 180 FU for 4" pipe. Maximum FU on vertical drain is 48 FU for 3" pipe and 240 FU for 4" pipe. That means that for a 3" pipe with 45 fixture units on it vertically you will need a 4" horizontal drain (only allows for 34 FUs on 3" horizontally), but 3" is fine vertical (allows up to 48FU). Another example is that you have 200 FU on a 4" vertical drain....which would require a 5" horizontal drain (4" only alllows for 180 FU horizontal so need to bump up to 5 inch pipe here... OR, say have 150 FU on 4" vertical...OK with 4" horizontal drain here).

Again, you need to check the maximum fixture unit tables in your area. In my area, we use the Massachusetts uniform state plumbing code and it is not always in perfect agreement with other codes across the country.

Let me know more if you can... maximum number of condos per complex/building, etc... and see if I can help a bit more.

The water distribution system is also determined by counting fixture units (values change from above numbers).


MARK

[WWPierre]

Thank you, Massplumber, for your prompt reply. We are planning a 8-10 story time-share hotel with a waterfront marine-oriented commercial component. It will take years to get the project through the local bureaucracy. In the meantime, we want to use it for temporary housing leading up to the 2010 Olympics by installing about 100 -120 trailers. We need to upgrade the sewer system for this purpose, and we feel that it would be best to install a system that would handle the ultimate end-use. (at least the hookup and the last 100' or so)

We will need to engineer this, of course, but I am trying to get a handle on the costs before committing to hiring the engineer.

Say 140 hotel rooms and 20,000 sq. ft. commercial. The Mass. Standard would be fine for a ballpark size for pipe. I am thinking maybe 6" water in and 10" sewer out. Close, do you think?

Peter

[massplumber2008]

Hey Peter... figure 10 fixture units per room for now... (bathtub, toilet, lavatory, kitchen sink and dishwasher per unit... ok? )... so 140 units x 10 FU = 1400 fixture units total.

In Massachusetts you can fit 1600 FU on an 8" horizontal drain pipe... so 8" would be enough IF no laundry rooms are needed, no commercial kitchen, etc...

I am thinking your guess of 10" drain will be best here, because you will need a commercial kitchen and a huge laundry facility. In Massachusetts you can fit up to 2900 FU on a 10" horizontal drain pipe with 1/8" pitch per foot of pipe (that should cover all bases). Also note here that a commercial kitchen will most likely require its own sewer main to enter the hotel SEPARATE of the hotel room drains and will require special grease interceptor (inside and outside if your area is anything like mine).

In terms of water supply, figuring as above... (bathtub, toilet, lavatory, kitchen sink and dishwasher per unit)... equals 13 fixture values (FV) x 140 units = 1820 FV times .70 (demand value for hotel) = 1275 FV. In Massachusetts a 6" water main will supply between 1100 and 1300 FVs... and if going to have a commercial kitchen and laundry room you will need to plan on bumping up to a 7 or 8" pipe.

What about fire protection/sprinkler mains...??

Let me know what you think here...

MARK

[WWPierre]

DANG, forgot about the sprinklers!

I think I will leave the supply side for later. We can supply the trailers with the existing 2" line probably. (maybe?) I never thought the water supply would have to be so big. It would surprise me if the old water line in the street, (probably asbestos cement) is bigger than 6"

We were going to gift the town with a granite seawall as an amenity. Maybe we will need to upgrade some waterline instead.

I guess I should probably walk up the street to the library for the local plumbing code instead of trying to ballpark it here.

But then I wouldn't have met the helpful Mark, :)

This is a great site. I just discovered it. I will be visiting frequently: Whenever I feel the need to pontificate. :) (often)

Peter

[massplumber2008]

Local library is a great idea!!

Drop back anytime you want to hash through things! Wait 'till you meet some of the other guys... a very knowledgeable bunch here with some experienced people so keep us posted as you go.

Good luck... MARK

[WWPierre]

Local library is a great idea!!

Drop back anytime you want to hash through things!! Wait 'till you meet some of the other guys...a very knowledgable bunch here with some experienced people so keep us posted as you go.

Good luck...MARK

Tomorrow I go to work designing and building a temporary trailer park on the land above. This is to derive some kind of income while the big project is in the planning and hoop-jumping stages. Phase 1 is 15 spaces. We had the sewer and water hookups engineered: 8" in and out. We are going to put a manhole just inside the property line and run the 8" sewer to it and the existing 4" out. This will handle phase 1 of the trailer park, and keep the bureaucrats off our back for a while. We figure the 2" water will handle the demand for the trailers. We are going to put the services in to be easily dismantled, except for the main 8" water line. All services will be in conduit under walkways with re-usable paving stones.

The Municipality is refusing a temporary use permit because it is in the Official Community Plan that TU permits can't be issued on land designated future residential in the OCP. We asked why such an odd provision in the OCP, but nobody at city hall can answer that, so we are persuing that. Case law says zoning overrules the OCP and zoning is industrial, so we are going ahead without any permits, mindful of codes. of course.

I just re-read your post above Mark, and am gonna push for a 10" sewer. Only 40 meters or so, so shouldn't cost significantly more.

[massplumber2008]

Thanks for the update WW... ;)

Sounds like a reasonable plan to me!

[speedball1]

Good morning Peter,

We are planning a 8-10 story time-share hotel with a waterfront marine-oriented commercial component.

Sounds like you may fall under Florida Codes. What area are you building on? This will inform us of the Plumbing Code that you must follow. Regards, tom

[WWPierre]

Good morning Peter,

Sounds like you may fall under Florida Codes. What area are you building on? This will inform us of the Plumbing Code that you must follow. regards, tom

Tom, I am in Squamish B.C. Halfway between Vancouver and the famous ski resort of Whistler.

If you want to see pics of my little empire, go to www.photobucket.com/wwpierre

There is a main album and three sub albums. For some reason the URL takes you to one of the sub albums.

In the next few days, I will try and produce a .jpg of my massing study for the project described above and post it in Photobucket. I'll bump this when I do.

Thanks for your interest guys.

Peter