Adding Plumbing to Existing Building

[TX63CONV]

Looking at a property that has a 30x50 metal building with a mezzanine on the short gabled side. I would like potentially build an office and bathroom upstairs but would need to add plumbing. Anyone gone in after the fact and can share some photos of how they accomplished this? Would be running to a septic but that is another thread.

 

[larry4406]

Hung sewer from below the mezzanine to location of your choice. Easy.

 

[dcg9381]

Looking at a property that has a 30x50 metal building with a mezzanine on the short gabled side. I would like potentially build an office and bathroom upstairs but would need to add plumbing. Anyone gone in after the fact and can share some photos of how they accomplished this? Would be running to a septic but that is another thread.

Not sure what you want. As the office / bath is upstairs, you've just got to get water in and water out. I did it before the fact by putting conduit and a 3" drain line in all the corners. For water, I just run 3/4" PEX through the electrical sleeve. But you can do it after the fact by adding a water main and drain on the side of the building through the steel. You'll need a "vent solution" for any drain, but that's easy.

Standard P-traps and slope designs apply, but you've got an upper floor, so should be easy.

My only hesitation would be "cold climate" where an exterior water line will likely freeze. You're in DFW, it'll happen, but not very frequently and if you use PEX, nothing is going to blow up.

I don't know DFW septic regulations, but down here in central Texas the one thing I cannot do is tap an existing septic and add beds/baths without a full engineering deal and redesign. And if I do it "anyway" it's all good until resale, where they WILL catch it.

 

[TX63CONV]

Thanks! pic above with drain, vent and water supply would be ideal if starting from scratch. Understood, I have lots of room to work since bathroom would be located upstairs.

What I was hoping to see was someone who has run the drain and supply on the 'outside' of the building. Is the other alternative to hammer out the concrete and run supply/drain under the slab--I would like to avoid this.

Actually relocated to Florida recently but similar wild west here--septic and well would need to be added.

 

[manwithtools]

I don't know DFW septic regulations, but down here in central Texas the one thing I cannot do is tap an existing septic and add beds/baths without a full engineering deal and redesign.

In many jurisdictions the septic system requirements are driven by the number of bedrooms only. You could have 12 bathrooms in a three bedroom house and the septic requirements would not change. When I built my shop and included a full bath and laundry setup, no septic permit or inspection was required because I did not add a bedroom.

 

[dcg9381]

What I was hoping to see was someone who has run the drain and supply on the 'outside' of the building. Is the other alternative to hammer out the concrete and run supply/drain under the slab--I would like to avoid this.

I'd assume you just run a 3" drain line out the side of the building and immediately attach a 90. Someone else will have to hammer you on if this meets code... but you see this stuff all the time in the big city.

In many jurisdictions the septic system requirements are driven by the number of bedrooms only. You could have 12 bathrooms in a three bedroom house and the septic requirements would not change. When I built my shop and included a full bath and laundry setup, no septic permit or inspection was required because I did not add a bedroom.

I get it. I don't know the septic design requirements if it's sinks, baths, sqft, whatever. I do know that here if you connect "anything" that wasn't in the original permit, they send you back to a septic engineer who is required to follow "current code". It's one of the biggest "sales gotchas" here. You literally sign a form that makes you liable for any deviation from the original design/permit at the time of sale.... In perpetuity.

 

[larry4406]

I'd assume you just run a 3" drain line out the side of the building and immediately attach a 90. Someone else will have to hammer you on if this meets code... but you see this stuff all the time in the big city.

We do this inside, and if there are no ground works below the concrete slab, we call it a hung sewer. Post 2.

 

[dcg9381]

we call it a hung sewer. Post 2.

How's that work in the winter? OP is in DFW, but we got some ****** weather a few years back and I froze 3" drain lines on an RV solid... There is no frost level in TX,but I'd just as soon go outside with a single 90 then drill a slab with steel in it.

 

[manwithtools]

OP is in DFW,

Actually relocated to Florida recently but similar wild west here--septic and well would need to be added.

Reading the whole post is sometimes important...

 

[larry4406]

How's that work in the winter? OP is in DFW, but we got some ****** weather a few years back and I froze 3" drain lines on an RV solid... There is no frost level in TX,but I'd just as soon go outside with a single 90 then drill a slab with steel in it.

Because its inside and you heat the place...

 

[75gmck25]

I would run all the horizontal pipe and elbows (in the picture) inside the building and then finally come through the wall and make a 90 degree turn to a vertical pipe into the ground. It would look better, and provide more protection for the pipe run.

 

[Hooked]

I did something similar in our garage when we decided to live in our garage while we built the house. When we built the garage I had included a 'bathroom' with a toilet only so I needed to add shower and vanity plus 'kitchen' sink. For the shower I drilled through the slab and dug under the slab (only about 2') to install the p-trap and drain coming to the side of the slab. For the vanity and kitchen sink drains I simply drilled through the wall and connected everything to drain pipe running underground next to the slab which then connected to the toilet drain pipe which was already connected to the septic system.

 

[rooster59]

On the serious side ...

 

[signcrafter]

Don't run it on the outside if you don't have to. It just looks horrible in my opinion. Run the stack down along an exterior wall on the inside. When you get close to the floor pop it outside and down into the ground. Can use that as a cleanout also.

There are too many variables to give any detailed layout. You didn't say what all fixtures you are going to have in your bathroom. But you will need drains, venting, and supply. Your layout and what all you are putting in there will determine how to plumb.

 

[matthe]

I agree with the comments about planning for future maintenance.

One thing I've learned on renovation and utility projects is that accessibility becomes much more important a few years down the road. A solution that looks clean today can become frustrating when repairs or upgrades are needed later.

If it were my project, I'd also think about how any future plumbing work, inspections, or modifications could be done with minimal demolition or disruption. Spending a little extra time on layout now often saves a lot of effort later.

Out of curiosity, are you planning any additional upgrades to the building while the plumbing work is being done?

 

[545_days]

I would hammer out a bit of concrete and run the lines in and out of the building underground. At the end of the day this would be the cleanest looking, and that would be important to both me and my wife.

 

[matthe]

I can definitely see the appeal of keeping everything underground from an appearance standpoint. A clean exterior is hard to argue with.

My only concern would be balancing the extra excavation and concrete work against the overall project cost and complexity. If the budget allows, though, the cleaner finished look would probably be worth it in the long run.