When RKM Homes designs and builds a custom house on your lot, rough‑in plumbing begins long before drywall goes up. We start with a detailed plumbing plan coordinated with the floor plan and structural framing so every toilet, tub, sink and appliance has a precisely placed stub‑out. That plan also factors in site conditions unique to Denver — utility locations, lot grade, and whether the house will tie into municipal water and sewer or a private well and septic system — and is submitted to the local building department as part of the permit process.
The physical rough‑in work follows a disciplined sequence: layout and mark all fixture locations, install drain‑waste‑vent (DWV) stacks and horizontal drain lines with the proper slope (typically about 1/4″ per foot for most domestic drains), and run supply piping (commonly PEX in new construction) for hot and cold with individual shutoffs at fixtures. Vent stacks are run up through the roof, cleanouts are installed at accessible points, and sleeves or protective plates are used where pipes pass through foundations and studs to prevent damage during framing. Once piping is in place we perform standard pressure or water tests to certify leak‑free systems, install required trap arms and cleanouts, and schedule the required rough‑in inspection before insulation and drywall are applied.
In Denver’s climate we also take specific precautions for freeze protection and service elevation: exterior hose bibs are frost‑proof, exposed lines are insulated or routed inside conditioned space, and sewer tie‑ins are handled with attention to drop and grade across the lot. We coordinate closely with electricians, HVAC, and framers to avoid conflicts and provide nail guards, access panels and clearly labeled stub‑outs so future maintenance is straightforward. Your RKM Homes project manager reviews the rough‑in layout with you and trades on site so we catch decisions now — when pipes are visible — rather than having to reopen walls later.
Where should fixtures be located and how are exact rough-in positions determined?
As a custom home builder I make fixture layout decisions early because the rough-in is driven by finished cabinetry, appliance specs and clearances — not by the drywall stage. Bring or request cabinet elevations, sink and toilet model numbers, and appliance installation manuals before rough plumbing begins. We measure and mark centerlines from the finished wall and finished floor elevations (including tile or underlayment thickness) so the drain and supply stubs will align with the installed fixtures and tops; if you change a vanity or appliance after that point the plumbing often has to be cut and reworked.
There are common starting points you can use to have a meaningful conversation with your plumber: most modern toilets use a 12″ rough-in (wall face to flange center), lavatory/drain outlet stubs for a standard vanity are usually set around 18″ above the finished floor, and kitchen sink drain and disposal trap centers are often 18–20″ AFF — but these are starting points, not absolutes. Hot/cold supply stubouts for sinks are typically 4–8″ on center and roughly 6–12″ above the floor depending on the faucet and cabinet depth. Always ask for manufacturer templates or spec sheets for tubs, showers, sinks and toilets and confirm the exact offsets before anyone sets a pipe.
Practical steps you can take on site: request that the plumber place bright centerline marks and labels on studs and subfloor and leave capped stub-outs visible, review the marked locations with your builder or designer, and verify clearance for things like cabinet drawers, toilet swing and tile base. Insist on blocking where you want accessories (grab bars, paper holders) while walls are open. Small offsets (an inch or two) are usually fixable in trim, but moving a drain or water line several inches after drywall is costly — get a walkthrough and sign-off on fixture locations before walls are closed.
Drainage, venting and required slopes
How should drainage slopes be set during rough‑in so drains flow reliably? As a builder who has stood over hundreds of starts, I insist on the right pitch from day one: horizontal waste lines 3″ and smaller are typically sloped 1/4″ per foot and 4″ mains 1/8″ per foot, and those are the numbers your plumber will use when running the lines before walls close. The slope is checked with a level and string line during rough‑in — too little pitch and solids settle, too much and liquids outrun solids causing build‑up — so ask the crew to show you the slope with a level and how the line drops to the main stack before drywall or subfloor goes over it.
Where and how should vents and vent connections be installed so fixtures don’t siphon dry? Vent piping is roughed in vertically and tied to the stack so every trap has an appropriately located vent or is part of an approved venting system; that means trap arms are limited in length and connected at the proper height, vent pipes remain unobstructed through walls, and they run up to the roofline where required. I make sure vent stubs are left accessible in attics and walls and that all roof penetrations and firestopping around vent pipes are marked so the roofer, drywallers and insulation crew don’t cover or compress them.
What practical checks should a homeowner do at the rough‑in inspection for drainage and venting? Walk the site with your plumber or builder and verify: slopes with a level/string, visible cleanouts at required locations and at direction changes, vent stubs in the attic or wall cavities, and that horizontal runs are supported and not squeezed between joists. Ask for an as‑built sketch or photos showing the mains, vent stack and cleanouts; that documentation saves time if a future remodel needs to relocate a wall or reconfigure fixtures.
What water supply materials, pipe sizes, pressure requirements and shutoffs should I expect during rough‑in plumbing?
As a Denver custom home builder, I specify materials that balance durability, ease of service and long‑term performance. Today that usually means PEX for most branch runs and copper or PEX for the main trunk from the meter. PEX is flexible, reduces the number of fittings behind walls and is much easier to route around framing — which speeds construction and lowers leak risk when installed with the right crimp or expansion fittings. If you prefer copper for visible runs or specific appliances, tell your builder early; that affects labor and manifold choices. Also confirm that the plumber is using oxygen‑barrier PEX for hot water and permanent mechanical connections (crimp/expansion) for buried or concealed work rather than push‑fit fittings that you’ll have to trust are hidden for the life of the house.
Expect the rough‑in to be sized for actual household demand rather than guesswork. Typical practice is a 3/4″ to 1″ service/main for a modern custom home, a 3/4″ trunk to supply multiple bathrooms, and 1/2″ or 3/8″ home‑run feeds from a manifold to individual fixtures depending on fixture type; kitchens and laundry often get 3/4″ branches for supply lines or dedicated 3/4″ ports on a manifold. Your plumber will size lines using fixture unit calculations, but a practical homeowner question to ask during rough‑in is how many simultaneous draws the system was designed for and whether the main was upsized for features like multiple showers, whole‑house filters or a future recirculation loop. For pressure, plan for 40–60 psi at fixtures as ideal; if municipal pressure is above 80 psi, insist on a pressure‑reducing valve at the meter and a thermal expansion tank on the water heater to protect fittings and fixtures.
Accessible and properly placed shutoffs are easy to overlook but critical once walls are closed. Require a single whole‑house shutoff near the meter or garage entry, quarter‑turn ball valves on major branches, and individual isolation shutoffs for appliances and each manifold run so you can service one bathroom without shutting down the whole house. Have the plumber locate shutoffs in predictable, accessible places—inside cabinets with labeled access panels, in utility closets or adjacent to the main manifold—and label everything on the as‑built plans. Before drywall, verify each shutoff operates smoothly and that the manifold ports are clearly marked; those small decisions during rough‑in save hours of tearing into walls later.
What building codes, permits and rough‑in inspections apply to rough‑in plumbing?
As a custom home builder in Denver, we always start by pulling the required plumbing permits and referencing the local amendments to the International Plumbing Code and the Colorado/Denver plumbing ordinances. Homeowners should ask to see the permit and the approved plan set for plumbing so they know what was signed off by the plan reviewer — that plan is the baseline the inspector will use when they come for the rough‑in inspection before drywall goes up. Expect the permit to list required inspections (usually a rough‑in and a final) and the contact information for the inspector or inspection portal so you can track status.
During the rough‑in inspection the inspector is verifying code compliance for items you can actually check: correct drain and vent layouts, required slopes (for most drain sizes the minimum fall is 1/4″ per foot, with larger mains allowed a gentler fall), proper vent connections and terminations, approved pipe materials and fittings, and that fixtures and appliances are positioned and supported per plan. They will also confirm that required cleanouts, shutoffs and backflow devices are shown and accessible. If anything deviates from the approved plans the inspector will issue a correction list that must be fixed and reinspected before the walls are closed.
Practical steps you can take are simple and will reduce delays: ask your builder to provide the permit number and the inspection schedule, request a copy of the inspector’s sign‑off card after rough‑in passes, and make sure any field changes were documented on revised plans or with an approved inspection note. If a correction is issued, get an estimate for the fix and expected reinspection date so you aren’t surprised by additional costs or schedule impacts. We also recommend being present (or having your rep present) for the rough‑in inspection so you can see any issues firsthand and confirm they are corrected before insulation and drywall seal the walls.
How are pressure/leak testing, cleanouts, access panels and coordination with other trades handled during rough‑in plumbing?
As a custom home builder I insist on a formal pressure/leak test before any insulation or drywall goes up. Plumbers will perform either an air test (commonly around 5 psi held for 10–15 minutes) or a hydrostatic test using a 10‑ft head of water (about 4.3 psi); local code can dictate which method is required. Practical steps you can take: ask to witness the test, request a photo of the gauge reading before and after the hold period, and require the crew to repair and retest any leaking joints until the gauge holds steady. Also confirm which sections are isolated during the test (all branches vs. main stacks) so you understand where a failure would be located and how it will be fixed.
Cleanouts and access panels are the plumbing’s future‑maintenance insurance — they must be visible and reachable once finishes are on. I make sure cleanouts are installed at critical change‑of‑direction points, at the base of stacks, and at intervals where drains can be rodded; they should never be buried behind permanent finishes. For valve access (tub/shower mixing valves, concealed shutoffs) ask the crew to provide appropriately sized access panels (small screw‑on panels for serviceable valves, larger keyed panels when necessary) and to place them in reasonable locations like closets or alcoves when possible. Have the plumber mark and photograph each cleanout and access panel location and add them to the as‑built drawings so you can find them decades later.
Coordination with framing, electrical, HVAC and drywall crews prevents accidental damage and costly rework. I schedule rough‑in plumbing and the pressure test before insulation and drywall, require framers to leave chases and blocking where pipes or access panels will be, and ask electricians to avoid running conduit through those chases. Protect exposed piping during other trades by capping lines, wrapping with rigid foam or roping off areas so drywallers don’t knock off fittings. For homeowners: request a short walkthrough after the rough test so the builder or plumber points out main and fixture shutoffs, shows cleanout and access panel locations, and hands you the photos/as‑built notes for service and warranty purposes.