On a new build, the plumbing decisions that matter most are made before anyone touches a pipe. Here is the sequence, with the things that reliably cause change orders flagged.
Before the site plan is final
- On a lot without sewer, get the soil evaluation. It determines the septic design, and the design determines where the house, driveway and reserve area can go.
- Confirm there is room for a primary drain field and the reserve area the county requires you to keep available.
- Establish where the water service and gas service will enter, and how far the run is.
- Check the total gas BTU load against what the meter can supply — before anyone specifies a tankless heater.
- Decide slab, crawlspace or basement. It changes how underground is run and what stays accessible later.
Permits — start the septic one first
On a septic lot, the wastewater permit is usually the critical path. Soil evaluation, application and approval typically add several weeks depending on county workload and weather.
The excavation itself is two to four days for a conventional system. So the office time, not the machine time, is what holds a schedule — and it can be run in parallel with everything else if it is started early.
More detail in our guide on new construction septic in Hamilton County.
Protect the field area from day one
This is the mistake that costs builders money and it is entirely preventable.
Once the field location is designated, nothing heavy goes on it. No concrete trucks, no material stockpiles, no excavator tracking across it, no construction parking. Compaction destroys soil structure permanently, and a site that evaluated fine can be ruined before the system is installed.
Stake it, flag it, and brief every trade on the job. It takes ten minutes and it protects the most expensive part of the system.
Underground phase
- DWV set to correct fall below slab or in crawl — this is where errors are permanent
- Sleeves through footings and slab where anything will pass later
- Water service and gas routed at proper depth with tracer where required
- Tested and inspected before any concrete is poured
- Positions verified against the actual fixture schedule, not generic dimensions
Rough-in phase
- Lock the fixture specification before rough-in. Late changes here are the number one source of change orders.
- Supply, drain and vent set at the right heights for the fixtures actually chosen
- Gas sized for the total connected BTU load, not just the appliance being installed now
- Venting and combustion air planned for whatever water heater is going in
- Coordinated with electrical and HVAC so nothing gets moved later
- Pressure-tested and inspected before insulation and drywall
Decisions worth making now
These cost almost nothing while walls are open and a great deal afterward.
- Run gas and venting for a tankless heater even if fitting a tank now — the retrofit costs several times the rough-in
- Use a PEX manifold layout so individual fixtures can be isolated without shutting the house down
- Fit a hose bib on each elevation rather than dragging a hose around the building
- Stub in for a future outdoor kitchen, pool fill or shop if there is any chance of one
- Fit a pressure-reducing valve with a thermal expansion tank if incoming pressure is high
- Size and stub the water softener loop now if the property is on a well
- On a septic lot, install risers so the lids sit at grade from day one
Trim-out and handover
- Fixtures set after tile and cabinets, at the right point in the schedule
- Water heater commissioned, temperature set, T&P discharge correctly routed
- Every fixture run and checked under pressure
- Owner shown the main shutoff, the water heater shutoffs, and — on septic — the lid positions
- As-built information handed over, including a measurement from a fixed point to each tank lid
The handover nobody does
That last item is worth insisting on. A new owner who knows where the main shutoff is, where the septic lids are, and what the pumping interval should be is far less likely to call you in year two with a problem that was preventable.
We work with builders on custom homes and small subdivisions across Ooltewah, Collegedale, Apison and the surrounding counties — and on septic lots we do both trades, which removes a whole layer of coordination. Details on our new construction page.
Frequently asked
On a septic lot, the wastewater permit. Soil evaluation, application and approval typically add several weeks depending on county workload, while the excavation itself is only two to four days. The office time is the critical path, and it can run in parallel with everything else if it is started early.
Before rough-in, without exception. Rough-in positions are set for the specific fixtures chosen — a freestanding tub, a multi-head shower system or a wall-hung basin all need different provision. Changing the specification after rough-in is the single most common source of change orders on a build.
No, and this is one of the most expensive construction mistakes there is. Compaction permanently destroys soil structure, and a site that evaluated fine can be ruined before the system is even installed. Stake and flag the field area at the start of the build and brief every trade on the job.
Need someone to actually look at it?
We are a licensed plumber and septic technician based in Ooltewah, serving Hamilton, Bradley and the surrounding counties. Free estimates on every job, and an honest answer about whether you need the work at all.
