Mechanical systems demand the most skill and knowledge during a bathroom remodel. Plumbing and electrical rough-ins also require permits and inspections.
Mechanicals are frequently contracted out to licensed professionals. It's something to consider if you feel uncomfortable about completing the work.
A few general things to think about: 1) developing plans and drawing diagrams of the new and existing systems, 2) tying into existing runs where possible, 3) obtaining permits and scheduling inspections.
A plumbing rough-in usually requires tearing up the subfloor to access existing pipes. Old pipes can usually be cut out with a reciprocating saw.
Most plumbing pipes are made of rigid plastic. In older homes, cast iron is common. But in some new construction instances, cast iron is used because it's quieter than plastic when water runs through it.
NOTE: Remember to stuff a rag in any open waste pipes to stop sewer gases.
Heavy and/or large bathtubs and whirlpools may require doubling the joists underneath them.
Doubling is especially needed when notching joists so drain pipes have proper flow. Check with your local building official to estimate the load the tub creates and the necessary support underneath it.
The following is a basic rundown of what's involved with bathroom wiring. You should have a good understanding of electrical work before starting any wiring.
If you feel uncomfortable about doing electrical work, contact a professional.
Diagram your wiring scheme to plan and double-check your work. You'll need to run new lines from the service panel (breaker box) to the bathroom, or tie into existing circuits and it's always easier to do that right after the framing is done.
Nail junction boxes to wall studs and joists where switches, outlets, or lights mount. Use a scrap of drywall or tile to set the boxes out the thickness of the finished wall/ceiling.
Drill 1" holes about knee high in the wall studs to run non-metallic, sheathed cable (Romex) to the boxes. Nail cable brackets (called "staples") every 4 1/2' to secure the cable. Pull the cables to their respective boxes and label them with a magic marker or tape.
GFCIs (Ground Fault Circuit Interrupter) are almost always required in bathrooms. They prevent electric shock by shutting down a circuit when a "short" interrupts normal current flow.
GFCIs have two main connections on the back: Line (incoming) and Load (to other outlets). There are also two buttons on the front: Test (to interrupt the circuit) and Reset (to restore power to the circuit).
Moving A Heat Run
Sometimes a bathroom remodeling project requires a heat run to be relocated.
You may not need a permit for a ductwork change, but if the project is an addition, a new heat load should be calculated for the house.
If the ductwork is tin, special tools are needed to bend and fit new pieces together. If you haven't worked with ductwork, or if you don't have the tools, it may be better to hire a heating contractor to relocate the run.
The register for our project set right under the vanity cabinet. So, we added a 90° boot to divert heat into the room.
In other instances, you may be able to tie into an existing run with a round adapter and run a flexible duct hose through the joists.