How To Calculate Drain Waste Pipe Sizes By Using Plumbing Fixture Units For Single Story House

in this video i will be providing you with the fundamentals that you can use to figure out the plumbing drain pipe sizes based off of the amount of fixture units or fixtures you have in your home and a fixture is nothing more than a bathtub toilet or a sink and the information in this video will be referring to single story homes only and i will be providing you with other videos about two-story or multi-story homes in the future and in hopes of trying to avoid confusing as many people as i possibly can i need to point out that the information i'm going to provide you with will be based off of the area located within the inside of the house and not the building drain line there are two different types of connections often referred to in plumbing one would be the sewer the next would be the drain line that is located outside of the house or the line that connects the sewer to the building and the diameter of this pipe might need to be larger depending upon the slope and the distance or length of it however this one right here cannot be smaller than this one here it can be larger it just can't be smaller and that goes for other pipes that are going to be connecting into it for example if this is a three inch line here i cannot put a four inch line over here however i can use the same size or smaller pipe so let's go ahead and install our form boards just to give us a point of reference here and the first pipe we're going to be looking at will be the kitchen sink and this will require a inch and a half pipe however i like to use a two inch pipe here to give me a little more insurance to prevent the pipe from being clogged because you are going to have a little more solid waste from the kitchen going down this pipe here again just something i like to do and i also like to make this pipe a little larger if i'm going to be sharing it with a kitchen sink and a dishwasher another reason might be the fact that the dishwasher is two units and the sink is two units and an inch and a half pipe only allows you to have three units where a two inch pipe allows you to have six fixture units and this is something that's not going to be questioned by the building inspector another reason to go a little bit larger would be if you're not a hundred percent sure what pipe diameter you're going to need then i would suggest installing the bigger pipe or contacting a local plumber or your local building authorities building department for more information so here we have a two inch drain dying into a three inch drain three inch going this way towards our bathroom let's go ahead and head over there and at the end of the line we have a clean out and make sure that you extend the same pipe diameter to the end here and use the appropriate clean out and not something smaller so since i have a three inch line here this is going to require a three inch cleanout and won't have anything to do with our drain fixture units however we are going to have a bathtub on this side bathtub on this side and the fixture unit size for each bathtub is going to be two and for a toilet it will be three you will have three fixture units for each toilet and then we will have one fixture unit for each sink so we will have a bathtub toilet sink in each bathroom we're gonna have a bathroom on this side of the wall we're gonna have another bathroom on this side of the wall and the last thing we're going to need to consider will be our wash machine drain and the washing machine drain we'll need a two inch drain pipe and we'll have two fixture units for that and for some of you you might not know what we were looking at so let's just go ahead and take a look at where these fixture units will be located and give you a better idea of what we were looking at here's the washing machine and the dryer located in the garage and if you remember we had a pipe coming up here splitting off here and then going to the bathrooms and then we had another pipe coming over and picking up the kitchen sink in the dishwasher let's just go ahead and zoom in there kitchen kitchen sink dishwasher and again we had a two inch pipe there just so we don't have to worry about it and then two bathrooms that are going to be identical so we have a bathroom with a bathtub a toilet and a sink and the other one is exactly the same so let's go ahead and pan out here and add up all of our fixtures we have a kitchen sink and then we have a dishwasher and then we have two bathtubs two toilets and two sinks and then last on our list will be the wash machine next up let's go ahead and add up the total amount of units we have one kitchen sink providing us with two units a dishwasher providing us with another two units and then since we have two bathtubs at two units each we're going to have four units and then since we have two bathroom sinks at one unit each we're going to have two units and the same with the toilets we're going to have two toilets so two times three is going to be six units and then last on the list we will have two more units for our washing machine providing us with a total of 18 units allowing us to use a three inch pipe however i don't think i would use a three inch pipe on something like this because you're cutting it too close i think i would change everything out to four inches i would have a four inch drain going all the way to the end here and the reason for that could be as simple as if you ever changed out one of the toilets that might have a higher water flow rate and a fixture unit rating of five in both of the bathrooms and you would be two fixture units over the rated size for a three inch pipe and if you're not going to make any modifications to the house then you don't have to worry about it you would be allowed to build something like this according to the building code book that i've referenced in the video and that your local county city or state will allow you to install that size pipe so i wouldn't get the cart ahead of the horse and say hey i'm putting a three inch pipe in here when your local building department's gonna want a four inch pipe and as always if you have any questions or comments feel free to leave them in the comment area and if you learned something new make sure you let us know by hitting the thumbs up button you

Channel: gregvancom

Views: 22,177

Keywords: house construction, remodeling, drain pipe, plumber, do it yourself, construction math, examples, ideas, methods

Id: QD0wsG_V9H8

Length: 7min 11sec (431 seconds)

Published: Fri Dec 31 2021