Floor Drainage

[dkaskie]

I am building a 32x48 footer/frame garage. I am debating on my trench drain location. I am planning to slope the floor from back to front.

I didn't really want a bunch of pitches to my floor within my garage. I plan to have my garage plenty high enough where I wont have any drainage issue with water entering the garage from the outside. So i was planning to put a trench drains INSIDE the garage rather than the outside running along the front garage door openings to allow me to spray out the garage or wash my car inside in the winter if I want to.

Thoughts??

 

[6768rogues]

I think that will work and it will prevent having the apron in front of your doors from being covered with ice from letting water out of the building. My son put his trench drains in the center of the front parking spaces, so they are centered under the cars parallel to the cars. Then water from the cars goes under and drains out, letting him walk on a dry floor. I have a 36x48 building with one 15" square drain in the middle of the front half. The front half is pitched to the drain and the back half is flat.

 

[LS6 Tommy]

Check with your AHJ. Many areas do not allow floor drains in residential garages, especially if they are not running through a grease trap or drain to the outdoors.

Tommy

 

[dkaskie]

I checked with AHJ. No trap required for residential. I planned to drain to outside drainage culvert along with running downspouts out there as well.

I am just wondering if anyone has put the trench drains inside their garage doors rather than outside their doors. I see a lot of pictures of people putting them outside their garage doors but I really don't see a need for that unless I am missing something.

 

[6768rogues]

Where to drain it varies with the jurisdiction. Here if the garage is on a public sanitary sewer, the authorities prefer to have drains connected to the sanitary sewer. Then any contaminants that go down the drain find their way to the treatment plant rather than being released into nearby streams. If the nature of what is being done justifies it, the authorities require an oil separator in the line from the building to the sewer.

 

[dkaskie]

There is no question of where I’m taking my water. The question and discussion was about where I am putting my trench drains.

 

[LS6 Tommy]

I checked with AHJ. No trap required for residential. I planned to drain to outside drainage culvert along with running downspouts out there as well.

I am just wondering if anyone has put the trench drains inside their garage doors rather than outside their doors. I see a lot of pictures of people putting them outside their garage doors but I really don't see a need for that unless I am missing something.

Sorry. I never finished my thought.
My experience is a trench drain outside the door is to stop outside water intrusion, drains inside are to drain off meltwater or car wash water and I've never seen anything other than a central floor drain(s), but I don't see any reason why your idea to keep the apron clear won't work.

Tommy

 

[bad_idea]

There is no question of where I’m taking my water. The question and discussion was about where I am putting my trench drains.

Welcome to the forum. Get used to this. Ask a question and folks tend to go off on a tangent quick. Good forum. Please don't let this discourage you from sticking around.

I am in the Southeast, so snow melt is not a concern for me. I wait until the 70 degree days to wash my car in January, so no need to do that in the garage either. I had my floor poured perfectly flat and level front to back and side to side. Has been great for laying out assemblies. Was such a PITA accounting for the floor slope when building things in the last garage.

That said, I would slope the floor in each bay to the center of the bay to one drain. Then pour the rest of the garage floor flat. Best of both worlds. If you are going to build a race car then I would have one bay poured flat and level to give you something to square the frame of the car to.

 

[OldNeons]

I built a 28x42 3 car last year and sloped the whole floor from back to front. I put a 3' wide trench drain parallel to each garage door about 6' in from door and sloped each bay to its respective drain. If I had to do it again I would put an 8-10' trench drain in the center of each bay (centered under where the car will park and running perpendicular to the doors). I say this as you have less distance to wash all the slop - and you can push it "under" the car from all sides instead of trying to get it all towards the front of the garage. I daylighted my drains, and did include a sediment trap in the last one (all 3 drains are connected going across the garage and out the side). What I have works ok, but I would make the change noted above if I did it again. People raise concerns about all the ups and downs in the floor - I don't care about that - it's a place to park my cars 365 days a year. I may place tables and chairs in there once a year and will deal with the wobbles..... It's not my workshop either so don't need a flat place to work. I want it drain all the slop off my cars and be easy to wash them/wash out the garage. It appears your garage is deeper than wide - mine was opposite. I would center drains under cars toward the doors - assuming the back area will be working space? I would also put tubing in the floor for radiant heat. I didn't and I'm kicking myself already. I will use a couple wall mount radiant heaters instead.....

 

[ConCretin]

I don't see the need for a trench drain, which works better for large areas that pitch in a single direction. A simple round drain would suffice for runoff from vehicles. I would locate the drain in the center of the area where you expect to park a vehicle. Pitch the concrete to the drain in a 10 x 20 area. Setting the drain an inch and a quarter low will provide 1/4" per foot of pitch in the short direction and an 1/8" in the long direction. The area around the perimeter where you walk and work can remain flat.

 

[OldNeons]

I will still contend that a trench drain under the car perpendicular to the door would do a much nicer job of controlling the slop we get in the Midwest winters. This would allow better drainage and easier washing with less manual clean up required.


Sent from my iPhone using Garage Journal

 

[dkaskie]

That’s a good consideration Thank you.

 

[4 FN 27]

I have a combination of both parallel and perpendicular trench drains in my Garages.

The upper Garage and Car Shop have floor drains parallel to the garage doors. Since the "room" is wider than it is deep I opted for this so I could have a flat area across the front of the Garage for Cabinets and a working area. Less shimming to get the Cabinets Flat. The floor is pitched 1/8" per foot and the drains are set 11 feet in from the door and the pitch goes towards the front of the Garage another 11 feet. The drop to the drain is 1.375 which works well for washing or winter melt off of snow and ice.

In my Lower Garage and the "Cold Storage" area of my shop I have 16 foot trench drains perpendicular to the doors. Again an 1/8" per foot taper starting 6 feet in from the door, add 16 feet for the trench drain and then another 6 feet towards the interior of the building. I keep the "Cold Storage" area at 50 degrees and when I come in from plowing I just park over the drain and let the melting happen.

My experience with a round drain is concrete guys have a very hard time getting the flow/pitch right going from a square/rectangular shape to a round while maintaining a pitch. Thus they only pitch the floor 2-3 feet around the drain leaving bird baths and you having to run squeegee for life.

From the looks of your picture your floor elevation is high enough that you can easily get a 1/4" per foot pitch outside for enough distance to keep water from intruding. On the parking area in front of my shop and on the upper and lower garages we used a 1/4" per foot pitch away from the doors and I have never had water intrusion even in a torrential downpour.

PM me and I can send pics later today.

 

[JOHN 86GT]

I would pick round drains over trench drains because the round drains trap the mid west winter sand and grit .

 

[Rockn4x4]

I debated a long time on what drains I wanted for my shop. I was going to place four 4" round drains in the shop. Two in each bay. The shop is 44' x 60'. When I started figuring out how much time it would take me to plumb them in and get them to the correct grade, I decided to spend a little more money up front and get the trench drains. My doors are 16' wide and so is the trench drain. I placed the trench drain two feet in from the door. My floor is flat. From my experience, you have to have a pretty decent slope to get water to move on a floor. My floor is heated so I planed on that drying my floor fairly quickly. If I need to, I just use a squeegee and direct the water to the drain.

 

[4 FN 27]

I would pick round drains over trench drains because the round drains trap the mid west winter sand and grit .

Trap it where?

 

[JOHN 86GT]

Trap it where?

I have a round drain that looks like this

https://www.homedepot.com/p/3-in-x-...Floor-Drain-with-Strainer-860-3PSPK/202274089

I guess they call it a strainer instead of a trap . If you remove the cover , there is kind of like a can on the inside that has holes around top edge and acts as a damn to let liquids over the top but not let sand etc get to the drain . I've had this drain over 15 years and works great . You would not believe how much sand is in there when it gets cleaned out a few times a year .

I do have a trench drain on a patio and it gets full of **** all the time but there is more stuff blowing around outside .

 

[tricountytrail]

I debated a long time on what drains I wanted for my shop. I was going to place four 4" round drains in the shop. Two in each bay. The shop is 44' x 60'. When I started figuring out how much time it would take me to plumb them in and get them to the correct grade, I decided to spend a little more money up front and get the trench drains. My doors are 16' wide and so is the trench drain. I placed the trench drain two feet in from the door. My floor is flat. From my experience, you have to have a pretty decent slope to get water to move on a floor. My floor is heated so I planed on that drying my floor fairly quickly. If I need to, I just use a squeegee and direct the water to the drain.

What did you use on the concrete as a sealer in this picture?

 

[Rockn4x4]

The floor was coated with Euclid Super Diamond Clear.

 

[AaronTTRS]

I'm also in Indiana. I'm building a new house and we did two 22 foot trench drains (one in front of each 18x8 door) inside the garage about 15 inches in front of the doors. I'm draining into the year about 5 feel deep. No oil/water separator for me.

I was just recently asking a similar question here, but a bit more tile related-

https://www.garagejournal.com/forum/showthread.php?t=404330