Rough-in inspection requirements cover everything a building inspector looks at inside your walls before insulation and drywall seal the work away: framing, plumbing drains and supply lines, electrical cables and boxes, HVAC ducts and gas piping, fireblocking, and the air barrier. The point of the visit is simple. Catch problems while the work is still exposed, because once the walls close up, fixing a mistake means tearing finished surfaces apart. Every jurisdiction operating under the International Residential Code requires this review before construction can move to the next phase.
What Has to Be Ready Before You Call
The structure needs to be “dried in” first. That means the roof covering and windows are installed so rain can’t reach the exposed pipes, wires, and ductwork. All fireblocking and draftstopping must be in place as well. Under IRC Section R302.11, fireblocking is required at ceiling and floor levels within stud walls, at connections between vertical and horizontal concealed spaces such as soffits and drop ceilings, between stair stringers, and around penetrations for pipes, ducts, and wiring at ceiling and floor levels.
Paperwork matters just as much as the work itself. The original building permit and the approved plan sets have to be physically on site. Inspectors routinely ask for manufacturer installation instructions for engineered products like trusses, I-joists, and specialized connectors so they can confirm the field work matches the engineering. Showing up without documents almost always triggers a failed inspection before the inspector looks at anything, along with a re-inspection fee.
Structural Framing
The inspector is checking whether the skeleton of the house matches the approved plans and meets code minimums. A handful of items draw consistent scrutiny:
- Headers and trimmers at window and door openings, properly sized and supported. Most openings wider than four feet require doubled trimmers.
- Joist hangers, straps, and hold-downs matching the type and size shown on the plans, with the correct fasteners. Galvanized or stainless hardware is required where pressure-treated or fire-retardant lumber is used.
- Anchor bolts securing sill plates to the foundation, with proper spacing, washers, and edge distances per the shear wall schedule.
- Lumber species and grade matching the plans, especially in load-bearing walls and areas carrying concentrated loads.
- Sheathing with panel joints landing on framing members, and fastener type, size, and spacing matching the approved nailing schedule.
If an engineered product was installed without following the manufacturer’s instructions, or those instructions aren’t on site, expect a correction notice.
Plumbing Rough-In
The plumbing portion covers drain, waste, and vent piping along with all water supply lines. Inspectors check that horizontal drains carry proper slope, that pipe materials fit their use, and that the layout matches the plans.
Nail Plates on Framing
Where plastic piping passes through a stud or joist and the pipe sits less than one and a quarter inches from the nearest edge of the framing, a steel nail plate at least 1/16 inch thick must cover the pipe path. Without it, a drywall screw or a trim nail can punch straight through the pipe. The same rule applies to electrical cables in the same position, so inspectors scan for these plates across every trade.
Pressure Testing
Nothing in plumbing passes without a leak test. For drain, waste, and vent piping, the standard test fills the system with water to create at least a 10-foot head of pressure and holds it for a minimum of 15 minutes with no drop. If the system is tested in sections, each section gets the same 10-foot head, and the upper portion of the previous section is retested so that virtually every joint sees at least that much pressure.1UpCodes. Drainage and Vent Rough-in Water Test – 312.2.1
Water supply lines get a separate test. The International Plumbing Code requires the supply system to hold pressure at no less than the normal working pressure of the system for at least 15 minutes. For non-plastic piping, an air test at no less than 50 PSI is an acceptable alternative.2ICC. IPC 2018 Chapter 6 – Water Supply and Distribution Residential water systems typically run between 40 and 80 PSI, so the test pressure is usually in that range. If a joint is going to fail, you want it to fail now.
Electrical Rough-In
At this stage all outlet boxes, junction boxes, and switch boxes are mounted on framing and the wiring has been pulled through the structure. The switches, receptacles, and fixtures stay off until later so the inspector can see bare conductor ends, insulation condition, and how cables are routed.
Cable Securing and Protection
Nonmetallic-sheathed cable (standard Romex) must be secured within 12 inches of every box and supported at intervals no greater than four and a half feet along the run.3Occupational Safety and Health Administration. Standard Interpretations – Maximum Allowable Distance Between Supports for Temporary Electrical Wiring Where cables pass through holes bored in studs or joists and the edge of the hole sits less than one and a quarter inches from the nearest edge of the framing, a steel protection plate at least 1/16 inch thick must cover the cable path.
Box Fill and Conductor Length
Every outlet and junction box has a maximum volume. The combined volume of conductors, clamps, devices, and ground wires inside cannot exceed that limit, because overstuffed boxes generate heat and raise fire risk. Inspectors count the wires entering each box and compare the total against the box’s rated capacity. Cramming too many circuits into a single box is caught constantly.
Each conductor must also extend at least six inches past the point where it enters the box, leaving enough slack for proper splicing or device connection. Where the box opening is less than eight inches in any direction, the wire must extend at least three inches outside the opening. The inspector checks this by looking at the bare wire ends sticking out of each box, which is exactly why devices aren’t installed yet.
Smoke and Carbon Monoxide Alarm Wiring
New construction requires hardwired, interconnected smoke alarms, so that one alarm detecting smoke triggers every alarm in the house. The rough-in phase is when electricians pull the dedicated wiring and mount the alarm boxes in the required spots. The National Fire Protection Association specifies alarms inside every bedroom, outside each sleeping area, on every level including the basement, and at the bottom of stairs leading to upper levels.4National Fire Protection Association. Installing and Maintaining Smoke Alarms Wall-mounted alarms sit within 12 inches of the ceiling, and all alarms must be at least 10 feet from cooking appliances to reduce nuisance trips. Carbon monoxide detectors follow a similar placement pattern in homes with attached garages or fuel-burning appliances.
Mechanical, HVAC, and Gas
Mechanical rough-in covers ductwork, exhaust fans, chimney liners, and gas piping. Duct joints need to be properly sealed for energy performance, and exhaust fans must vent directly to the exterior rather than discharging into the attic. Moisture dumped into attic spaces is one of the most common causes of mold and structural rot in residential roofs, and inspectors flag it on sight.
Gas Piping Pressure Test
Gas piping gets its own test, separate from the plumbing system. The standard approach pressurizes the gas lines with air to at least 10 PSI and holds that pressure with no perceptible drop for a minimum of 15 minutes. Welded piping or systems operating above 14 inches of water column pressure face a higher bar: 60 PSI held for at least 30 minutes. Any pressure drop means a leak that must be found and corrected before the inspection can pass.
Inspectors also verify a sediment trap downstream of each appliance shutoff valve, placed as close to the appliance inlet as practical. A sediment trap is typically a tee fitting with a capped vertical nipple at the bottom that catches debris before it reaches furnace or water heater components.5UpCodes. 408.4 Sediment Trap Missing sediment traps are an easy fix, but they still trigger a re-inspection.
Combustion Air
Fuel-burning appliances need adequate combustion air to operate safely. When an appliance sits in a confined space without enough indoor air volume, the code requires outdoor combustion air openings sized based on BTU input, the number of openings, and whether the air comes directly from outside or through ducts.6U.S. Department of Energy. Combustion Safety in the Codes Where mechanical ventilation supplies combustion air, it must deliver at least 0.35 cubic feet per minute for every 1,000 BTU/hour of appliance input and be interlocked so the appliances cannot fire without the ventilation running. Getting this wrong introduces carbon monoxide risk, which is why inspectors pay close attention here.
Energy Code Air Sealing
Modern energy codes have added a serious layer to the rough-in review. Before insulation goes in, the inspector verifies that the air barrier is sealed at every penetration between conditioned and unconditioned space. The list is long and easy to overlook. Typical checkpoints:
- Gaps around plumbing pipes, electrical wires, HVAC ducts, and flues, sealed with caulk, foam, or rigid blocking.
- Window and door frames sealed between the jamb and the framing.
- The sill plate at the foundation and the top plate at the ceiling, both sealed.
- Electrical boxes in exterior walls, either air-sealed by design or backed by a sealed air barrier.
- Rim joists at the band area where the floor system meets the exterior wall, insulated and sealed.
- Recessed lighting in the thermal envelope that is air-tight and IC-rated for direct contact with insulation.
- Dropped soffits, chase ways, and openings under knee walls closed off with rigid material sealed at the edges.
Some jurisdictions also require a duct leakage test at the rough-in stage when ducts or air handlers sit outside conditioned space. The test measures total duct leakage at a set pressure differential, and the system must come in below a threshold tied to the conditioned floor area. Failing the test means pulling apart joints and resealing them before insulation can go in.
The Visit and What a Failure Means
Scheduling happens through the local building department. The contractor or owner-builder should be on site with access to every area of the building. The inspector walks the structure, checking each trade against the approved plans. A pass results in a green tag or approval stamp on the permit card. A failure produces a correction report listing each item.
A failed inspection does not mean the project is in trouble. It means specific items need attention. Common failures include missing nail plates, unsecured cables, unsealed air barrier penetrations, and incomplete fireblocking. Once the fixes are made, a re-inspection gets scheduled. Work cannot move forward to insulation and drywall until the rough-in passes.
If You Skip It
Covering work before it has been inspected creates problems that compound. The building department can issue a stop-work order and require you to open finished walls to expose the uninspected work, which costs far more than getting the inspection right the first time. Fines vary widely by jurisdiction and can run into hundreds or thousands of dollars.
The financial exposure runs further than fines. Homeowners insurance policies may not cover damage claims tied to work that was never permitted or inspected. A burst pipe behind an uninspected plumbing rough-in, or a fire traced to uninspected wiring, could leave you without coverage for the resulting damage. When you sell, most states require you to disclose known unpermitted construction. Appraisers will not factor unpermitted square footage or improvements into the home’s value, and many buyers walk away rather than inherit the risk. Those willing to proceed will demand a lower price.
The rough-in approval becomes a permanent part of the property’s building history. It documents that the work now hidden behind your walls met code at the time of construction, and that record protects you for as long as you own the home.