New Construction Plumbing in Decatur, GA

When a family outgrows a house on a small lot, building up is often the only direction left. A second-story addition, or an upstairs suite carved out of attic space, is new construction plumbing with an unusual problem: the new bathrooms sit above a finished, occupied home, and their drains have to find a way down through it. In an older Decatur house, that trip down can also reveal exactly what the original pipes are made of.

Finding a path down

An upstairs bathroom needs a drain stack that drops to the building drain below the first floor, plus a vent that rises through the new roof. The cleanest path is a chase: a closet corner, a pair of stacked closets, or a wall that lines up on both floors. Where nothing lines up, the stack may have to jog, which means opening first-floor ceilings and walls and working around joists and beams that cannot be cut. The plumber and the designer should agree on that route before the framing plans are final. Once the route is settled, the addition gets the same rough-in, testing and final steps as any new construction plumbing.

Stacking the new layout over the old

• Put the new bathroom above an existing bathroom or kitchen when possible, so its drain can join existing piping with a short connection.
• Keep the toilet close to the stack, since its drain is the largest and needs the most room in the floor framing.
• Run supply lines through the same chase so future access stays in one place.
• Plan an upstairs laundry only with a drain pan and a clear route for its drain and vent.

What the existing house has to carry

More fixtures upstairs mean more flow through the building drain and the sewer line leaving the house. If that line is old clay or cast iron, or has a history of backups, have it checked before the addition adds to its workload; repair or replacement of that section is handled by our main sewer line repair team. On the supply side, an older house may still have galvanized steel lines in its walls. They corrode from the inside and restrict flow, and an upstairs shower makes that weakness obvious. With walls already open, many owners decide this is the moment for whole house repiping.

Water pressure at the top floor

Water loses some pressure as it climbs, so an upstairs shower always sees a bit less than a ground-floor faucet. Correctly sized supply lines, a short route from the main and a properly adjusted pressure-reducing valve, where the house has one, keep the difference small. A new floor is also a good reason to recheck the water heater's capacity and location.

Decatur's permit rules for trade work

Decatur's Design, Environment and Construction Division explains in its guide to obtaining a permit that sewer, drainage and plumbing work each need their own trade permit, whatever the job costs. For an addition, the plumbing permit is therefore its own application, apart from the building permit, and it is filed and inspected through the city's online system.

Living below the construction

Second-story work happens over people's heads. Expect sections of the first-floor ceiling to come down where the new stack passes, and plan for a short shutdown when the new drain ties into the old one. Protect floors and furniture in the rooms below, and keep one bathroom working throughout.

Questions about adding a floor in Decatur

Can an upstairs bathroom drain without a new stack?

Sometimes, if it sits near an existing stack with enough capacity and the connection can satisfy the code for slope and venting. More often a second-story addition needs its own stack, because the existing ones are in the wrong place or too small for the added load. The plumber decides after looking at the existing piping and the new layout side by side.

Can the plumbing be roughed in before the new roof is on?

Rough-in generally waits until the new floor is framed and the roof is dried in, so rain cannot soak open framing or the rooms below. The drain route through the first floor can sometimes be opened and prepared earlier, but the upstairs piping, the vent and its roof penetration follow the roof. Coordinating the vent with the roofer avoids patching new shingles.

Will the upstairs shower have weak pressure?

Some loss is unavoidable: each foot of rise costs a little under half a pound per square inch, so a shower one floor up typically sees a few psi less than the kitchen sink. That difference is minor when the lines are sized correctly and becomes noticeable when old galvanized pipe or long, undersized runs add friction. A gauge reading on the new floor during rough-in shows where the system stands.

Talk to us before the roof comes off

Thinking about adding a floor to your Decatur home? Give Alpha a call at (404) 409-4448 while the design is still flexible enough to line up the plumbing.