What hidden costs should I plan for in an older home?

Older homes can be tricky from framing to electrical, plumbing, insulation and hazardous materials. Those are the things you have to consider when you remodel an older home, and most of what you find traces back to the era the house was built in.

Framing

Framing in older homes can make things easier to manipulate. In newer homes with engineered trusses, it can be difficult to remodel and provide vaulted ceilings, because those trusses may not be able to be modified. In a conventionally framed older home, the ceiling framing may be able to be re-engineered and modified more simply.

Some older homes were framed with old-growth lumber that is fairly straight compared to today's standards, and in certain cases homes were framed more robustly than they are today because the engineered products we have now did not exist. There is good and bad in much of that. Most of the reason we have engineered framing products today is to save money, reduce weight, create products made from wood byproducts, and produce material that is much straighter and flatter than traditionally milled lumber.

Electrical

Electrical systems are where you can really see the progression through the decades, especially in the greater Sacramento area.

Knob and tube

In homes from the 20s, 30s and 40s you can run into knob and tube. It was one of the first home wiring systems ever, installed in homes in the 1800s when they were first being electrified, and it was really the standard until later in the 1930s before being effectively phased out and taken over by new systems into the 40s. It was basically two wires in the wall, one hot and one neutral, with a porcelain knob or insulator holding the wires off the framing.

It was a decent solution at the time, but it has not aged well. The cloth wrapping around the wire eventually deteriorates, leaving a fully exposed and electrified wire running through walls, ceilings or floors. Aside from the deterioration issue, the biggest problem against today's systems is that it is only a two-wire system. It is not safe for our modern three-prong loads. There is no ground wire and no path to a ground fault unless one is retrofitted into the system.

One reason we still see knob and tube installed and functioning in a home today is that most wall cavities in that time frame did not have insulation, and these systems actually needed air to cool — they shed heat into open air. As insulation became more prominent into the 50s and 60s, and as retrofitting insulation became more prominent even in the 90s and 2000s, people could drill holes through drywall or create access points during an exterior remodel to blow insulation into the empty wall cavities. In that situation, knob and tube that is still energized could overheat and cause fire.

One of the biggest problems we see, though, is not simply that these systems are still active. As we open walls for remodels, we sometimes see amateur or DIY splices where the old knob and tube has been spliced onto a newer system. That is not a risk anybody should take with their electrical system.

Cloth wire

Beyond knob and tube, into the 50s and 60s most electricians had transitioned to cloth wire. It was basically the earliest form of what most people now refer to as Romex — not the same as what we have now, but a close relative that has simply been improved into what it is today. It was very prominent from the late 30s and early 40s through most of the 60s, although plenty of people made the full transition to the plastic-jacketed cables we use now into the mid and late 60s, and that was pretty much standard by the 70s.

Cloth wire was a rubber-insulated wire bundled inside a cloth jacket, and that jacket was often soaked with tar. The biggest benefit was that it could be run as a single wire, because the conductors were bundled together into one sheathing. The earliest versions were still just two-wire systems, so they did not include a ground wire. That transition to grounded wire systems did not take place until the early to mid 60s, when the NEC started requiring grounded outlets on any new work.

The main issue with cloth wire is that the rubber insulation dries out, gets brittle and crumbles, especially inside the light fixture boxes where the light itself generates heat and cooks the insulation around the wire. We have had so many remodels where the task was simply removing a light and putting a new one in, only to realize there is an older cloth wire system and the insulation crumbles as you touch it. In those situations there is not a lot you can do outside of replacing that circuit entirely. Cloth wire was much better than knob and tube and did not need air to cool it, but insulation that dries out and cracks makes it nearly as dangerous.

Anything from the late 60s to 70s forward has the thermoplastic or PVC insulated wire we use today, so most of the time we have a pretty good idea of what to expect from these systems across the different eras.

Plumbing

Plumbing followed a similar path. In the early 1900s nearly everybody had electricity, but most homes before 1920 still did not have indoor plumbing. Most of the pre-1920 homes you see in the Sacramento area are actually retrofit, and sometimes you can see it, because the cast iron pipes are mounted on the outside of the home in an effort to reduce the work on the inside. Through this time most rural homes still had outhouses and either wells or hand pumps for bathing and drinking water.

Most supply lines were made from lead, and especially as cities started adopting their own water systems to deliver potable water to residential homes, those underground pipes were generally lead or galvanized steel. Drains were generally cast iron with the joints packed with lead and oakum, and once the pipe hit the ground it would transition to clay piping discharging to a sewer, a septic tank or a cesspool.

In the 1920s through most of the 40s, indoor bathrooms became standard in new homes, though even in the 40s many homes still lacked a complete plumbing system. Galvanized systems were very much the norm, and copper really did not become prominent until the 1930s. Cast iron drains were still the go-to drain system and clay laterals were still the norm for underground systems.

In the 50s and 60s most supply lines had transitioned to copper, although galvanized systems were still being built. Drains were again still cast iron, and cast iron was even still being improved in terms of its connections well into the 60s and 70s. The plastic systems we have now — ABS for drain, waste and vent, or PVC — did not arrive until the late 50s and even well into the 60s.

The 1970s is really where we saw most of these systems have significant improvements, and that is a big part of why we have a much better time understanding what we are likely to get into on homes of the 70s and newer. The drains in the 70s were more predominantly ABS and PVC, which was a much lighter way of moving pipe around. Cast iron pipe was extremely heavy and difficult to align and install, while with ABS one person could easily install 10 foot long sections with very little effort.

Copper water supply really dominated up until the early 2000s. Copper is now fairly rare in new builds and PEX is basically the default. There are still plenty of plumbers who insist on working only with copper, and to be honest there is nothing wrong with that. Both systems really do have their pros and cons. I am a fan of both copper and PEX, and I think they both have places where they are significantly better in certain scenarios.

We do still have to be mindful that many of the older materials, lead for example, did not actually become banned until well into the 80s. So while most systems were copper into the 70s and 80s, we still do assessments in preconstruction to identify the existing systems, and where we notice systems that are dangerous or have been banned, we provide an option to bypass or replace them.

Another thing people do not think about when they identify copper systems in homes of the 70s and 80s is that solder joints back then frequently contained lead. People see a copper system and think they have some amazing new system, but the reality is that it is really difficult to tell whether that system contains connections that are no longer legal or up to today's standards. It is worth finding a contractor who can identify these things for you, so you are not extending new systems off old systems that may still contain lead.

Insulation and hazardous materials

Through the 20s, homes mostly relied on thick plaster, masonry and the fireplace to stay warm. If you did encounter insulation from this era, it was usually whatever was handy filling the voids — sawdust, newspaper, corn cobs, wood shavings. We have even seen seaweed filling wall cavities. People understood that filling those cavities was adding some insulating value, and the homes were leaky, but those air leaks actually helped keep the homes dry. That is something we deal with as builders in new home construction today, because the houses are effectively airtight and do not breathe at all, so we have to retrofit certain systems in an effort to provide air circulation.

The earliest true insulation products came into play mostly in the 30s and 40s: rock wool and balsam wool, which was a wood fiber in paper, and Celotex fiberboard sheathing. There was also a loose-fill vermiculite that started showing up in attics, and much of that came from an old Montana mine that was contaminated with asbestos. More and more people are becoming privy to these old materials, understanding that they may be present and figuring out how to remove them at their next remodel.

Fiberglass insulation similar to what we have now was actually invented in the 30s but did not start to become more prominent until the 50s and 60s. Most of those fiberglass batts were very thin, maybe only one or two inches thick, whereas now you see them fill the entire cavity of the wall. The vermiculite loose fill was still completely normal and common through the 50s and 60s, as the concerns around asbestos were nowhere near as prominent as they became into the 70s and 80s and beyond. Asbestos was on pipes and ducts and in popcorn ceilings, and it was also in a lot of the sheet goods used in those times.

The 70s is really where we started to get into the actual energy crisis, where California started implementing its current Title 24, or energy calculations, and that is where the code started changing into the mid and late 70s. After that, blown-in cellulose absolutely boomed, because it was an easy way to install a lot of insulation in a short amount of time and it was fairly inexpensive. Spray foam did not catch much attention until the late 90s and even early 2000s, and even today in 2026 we still much more commonly use fiberglass batt insulation for most of the builds we do in California.

What to do before you start

If you know the era your home was built in, it is pretty easy to do a quick Google search or use current AI systems like ChatGPT or Claude to identify what may be present before you get involved with a remodel project. Your contractor should be able to tell you as well. Anyone with a good preconstruction process should be able to identify these materials for you or help you find somebody who can, and in certain eras the best practice is simply to have a reputable testing agency come test certain surfaces and products, so you understand what hazardous materials may be present and how they should be handled during the remodel.

People sometimes think there are significant increases in cost to remove or work around these systems, and that is not always the case. In some situations it is completely safe to leave some of these older systems in place and undisturbed. In others it is wise to change out what we might otherwise call a ticking time bomb. Some of these old electrical and plumbing systems are likely to cost more to replace or repair as an emergency than they would as a planned project, and that is something to keep in mind as you are thinking about a remodeling project.