Whole-Home Remodel Series: Behind the Walls

Welcome back to our Whole-Home Remodel Series! In this post, we’re giving you a look at what’s commonly found behind the walls of our San Francisco remodels before the drywall and finishes are installed. We’ll take a look at the heating, electrical, and plumbing systems that, although hidden behind the drywall, are the workhorses of the home! (Don’t miss our first two posts in the series: The Planning Stage and Tips for Hiring a Contractor.)

Rough electrical and plumbing for a guest bathroom

Once the rough framing (including the floors, walls, and roof systems) of the home is complete, we have what is known as the shell or skeleton of the home. A protective barrier, or house wrap, is applied to the exterior to prevent water from infiltrating the shell while allowing moisture to escape which reduces the likelihood of rot and mold. And now the house is ready for the mechanical, electrical, and plumbing (MEP) contractors to work their magic! Let’s dive in and take a look.

Mechanical Rough-in


HVAC installation in full gear with new ducting

Ductwork for the heating, ventilation, and air conditioning (HVAC) system is usually installed before plumbing supply and electrical work begins because it’s a lot easier to run wires around ductwork and pipes than the other way around. As we noted in this post, an effective ventilation system serves two main purposes: to improve air quality and to decrease humidity. Therefore, it makes sense that kitchens and bathrooms are the two rooms that benefit the most from well-thought-out and expertly executed ventilation systems.

There are two types of heating systems: forced air and radiant heating. When installing forced air systems, it’s important to make sure they are sized according to the home and it’s important to use high-efficiency furnaces.

High-efficiency furnaces

Radiant heat flooring is a popular feature we add to many of our remodels, which is an especially nice feature to have here in San Francisco where temperatures tend to be cool year round. There are two main types of radiant heating to consider: electric and hydronic.

Electronic Radiant Floor Heating:
  • better suited for smaller spaces, such as a bathroom
  • designed to be used for comfort, not as a primary heating source
  • powered by electric cables or mats of electrically conductive plastic built into the floor
Hydronic Radiant Floor Heating:
  • designed for larger spaces, typically the entire home
  • provides a gentle, consistent warmth
  • heater water is pumped from a boiler through a network of tubing underneath the floor
Hydronic radiant floor heating

For a more in-depth look at the pros & cons of both radiant floor heating systems, read this post we wrote.

Plumbing Rough-in

Tub install during the rough plumbing phase

Rough plumbing involves installing all of the home’s water supply lines (they deliver the clean water into the home) and sewer lines and vents (these drain the water and waste from the home) through studs and under floors to kitchen and bathroom sinks, toilets, showers, bathtubs, laundry rooms, etc. Pipes are fitted and connected to each other, but no fixtures or any end elements are attached at this point.

Supply pipes installed during plumbing rough in

Supply pipes extend into the home from the main service line of the water source (e.g., municipal water supply or well). The main cold-water pipe divides, sending water to the water heater and to the various cold-water fixtures in the home. A hot-water pipe is connected to the water heater and distributes hot water throughout the home in a similar fashion. Supply pipes must maintain pressure at all times, so the pipes must be tightly joined.

Waste pipes, on the other hand, work with gravity and are not pressurized, so all waste pipes must slope downward. (During this rough-in phase, the waste pipes are pressurized and filled with water to test for leaks.) Waste systems are also vented, usually through the roof, which allows water to flow smoothly out to the sewer and keeps the gasses outside the home. Waste system pipes are larger than supply pipes, so this system is usually installed before the supply pipes.

Super boiler for on-demand hot water and radiant floor heat

Electrical Rough-in

Can light installation during rough electrical phase

The home’s electrical system is designed to distribute the power safely to all of the various rooms and appliances throughout. In order to do this, the electrician has to install receptacles at all of the electrical outlets, lights, and switches and then runs wires from the breaker panel to each of the receptacles. Wiring for telephones, cable TV, music systems, and security systems are also included at this time. Most major appliances (e.g., a water pump, hot water heater, range, refrigerator) have separate lines and dedicated circuits with their own breakers.

Can lighting, also known as recessed lighting, is a popular choice for many residential and commercial projects as they offer unobtrusive light sources that won’t compete with the overall design scheme. This type of lighting typically provides most, if not all, of the lighting in a given room, but they’re also great for task lighting when positioned directly over a particular area. For example, when installing can lighting in a kitchen, it’s a smart idea to place some of them directly over the work surfaces (e.g., counters, island, sink, stovetop), this way the cans are illuminating the entire room while at the same time providing direct light and the areas where it’s needed most. One thing to keep in mind with can lights is that while these lights provide a clean, modern look to the interior, they do require a lot of space behind the drywall! Read more about the energy-efficient benefits of can lighting in this post.

Another relatively recent development is the introduction of smart lighting systems that allow you to set the scene/mood of any given room. For example, a dining scene will dim the lights, while a clean-up scene brings them up. In addition to their convenience factor (many have features that allow you to control the lights from anywhere in the room, within the home, or even outside the home) these ambiance-enhancing features, may also save energy and money with the use of dimmers, timers, and sensors. Dimmers save energy every time you use your lights; set timers to automatically turn off bathroom exhaust fans with a timer, and utilize sensors to prevent unoccupied rooms aren’t unnecessarily lit.

A look inside an electrical control panel
Rough electrical in progress, making up the panel boxes

When the rough electrical is complete, there’ll be a new nest of wires that extend from the electrical panel (usually found in the basement or garage) to new boxes attached to the framing, where the plugs, switches, and fixtures will eventually be mounted. (These boxes are set at a consistent height so that when the drywall is installed, each box is concealed neatly behind the plane of the wall.)

Let’s take a look at a few, not-so-basic features that you may want to consider adding to your home, such as solar panels, a central vacuum, and a hot water re-circulating system as this is the time these are installed.

Solar Panels

Since we’re talking about electrical work, it’s a great time to think about adding solar panels to your roof. (Although the solar panels would get installed during a later phase, all necessary rough electrical work would happen now.) Going solar is an especially great choice if you’re looking to reduce your energy bills and carbon footprint. Contrary to most electricity sources, sunshine is abundant, unlimited, and free.

Solar panels work by converting the sun’s energy into electricity using photovoltaic technology. When the energy from the sun’s rays hit the panels, semiconductors turn it into electrons of direct current (DC) electricity. This newly created DC power is then fed into an inverter, which transforms it into alternating current (AC), which allows it to become the power source for your home’s electrical panel. Utilizing a bi-directional meter, the energy going into your home (via the power your panels produce) is measured against the power you use. While the ultimate goal is to generate more electricity than you use, how much electricity you generate largely depends on the size of the photovoltaic system and the number of solar panels installed. If you’re looking for a more in-depth explanation of residential solar PV systems, check out this post we wrote.

And if you need some inspiration for ways in which you can reduce your carbon footprint and save money, read this case study. We helped our clients save over $250/month on their utility bills by installing new insulation, windows, lighting, and high-efficiency appliances during their remodel.

Central Vacuum

In a nutshell, a central vacuum is a semi-permanent appliance that’s installed in the home. The vacuum’s power unit and debris collection container are typically installed in the basement or garage while several inlets are installed in the walls throughout the home. Tubing that’s installed inside the walls connects all of the inlets to the debris collection container. So, when it comes time to vacuum, one simply needs to attach a hose to the inlet rather than lug around a portable machine. All of the dust and debris that’s vacuumed up via the power hose is whisked away to the collection container.

Although they operate similarly to portable vacuum cleaners, there are a few notable advantages of a central vacuum, including:

  • Complete removal of allergens
  • Low acoustic noise
  • Greater suction power
  • Ability to vacuum fine particle debris such as plaster dust, printer toner, flour, as well as broken glass
  • Easy cleaning & infrequent emptying of debris container
  • Low usage cost for filterless systems
  • Easy to use (ports are installed throughout the home, which means no more lugging a vacuum around! Simply put out the wand at the designated port!)
  • Durability (many manufacturers offer a limited lifetime warranty)

While the initial cost of installing a central vacuum is relatively high, it is definitely worth considering if you’re already planning a remodel.

Hot Water Re-Circulating System

Installing a hot water re-circulating system ensures that hot water is immediately available at the faucet, reducing the amount of water that’s wasted while waiting for it to heat up. There are two types of re-circulating systems, in-line systems and trunk line systems, both of which are equally effective, the differences are mainly about design. In an in-line system, pipes form one continuous loop from the hot water heater to each faucet, whereas, in a trunk line system, water runs around a centralized trunk, or loop, with lines for each faucet branching off from the trunk.

Motion sensor activation for hot water circulation in bathroom

While there are three main types of systems (on demand/self-activated, timer controlled, and thermostat controlled), the on-demand/self-activated approach is generally considered the best for energy conservation reasons.


Once all of the rough plumbing and rough electrical work is done, it’s time to install the insulation.

Batt insulation installed at exterior walls

Insulation is rated by how well it resists heat transfer; this is measured by its thermal performance or R-value. There are various types of insulation (fiberglass, cellulose, mineral wool, foam board, open- and closed-cell spray foam) and which type you use depends on your region and climate.

Spray foam insulation applied at the ceiling (and around a can light)

In our San Francisco remodels, we typically use blown-in fiberglass for existing walls and ceilings, fiberglass batts for open exterior walls and ceilings, and spray foam for ceilings and roofs. Regardless of which type of insulation is used, our aim is to exceed the Air Quality Requirements of California, reduce energy levels, and increase thermal performance. At Jeff King & Company, we use insulation that’s environmentally responsible and has energy-savings properties, such as renewable fiberglass with plant-based binders and that’s free of formaldehyde, acrylic, and dye. These measures are good for our clients’ health, good for the environment, and saves our clients money!

Installation of resilient channel soundproofing

Not only does insulation play a vital role in ensuring the home keeps a comfortable, consistent temperature and significantly improves the home’s energy efficiency, insulation also aids in soundproofing. A few methods for creating a soundproofed room include installing batt channel insulation between the studs or joists, installing a double layer of drywall, installing an isolation system (such as resilient channels) across the wall, and using mass-loaded vinyl.

Insulation (from recycled jeans!) and mass loaded vinyl insulation to provide extra soundproofing

For another example of how we utilized energy-efficient methods in one of our San Francisco remodels, read this case study of our Twin Peaks project.

Drywall is up

Now that we’re done with the rough mechanical, electrical, and plumbing and the insulation is installed, it’s time to hang the drywall. Stay tuned for our final post in this series where we’ll highlight some of the more popular finishes.