How To Look At A House

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What are the common problems of 1920s houses?

Friday, May 6, 2022

The Roaring ‘20s was exactly that: full speed ahead. While the economy surged and the stock market kept hitting new highs, over 4 million homes were built. That was twice as many as the decade before, and 60% more than during the depression years of the 1930s. Homes were also larger and more ornate than a the decades before and after.

    Here’s our list of problems to look for when buying a 1920s house. But keep in mind that many of them may have already been fixed by multiple generations of homeowners over the years.

Knob and Tube Wiring

Knob and tube is an insurance no-no. Most companies will not write a new homeowner’s policy for a house with knob and tube wiring. 

   It’s also sometimes called K&T, and part of the challenge home inspectors have when inspecting 1920s homes is determining if “active” K&T is present. Most of them have had the wiring completely replaced, but sections of the abandoned, old knob and tube equipment may still in place in the attic and under the floor. Then again, some homes have had only part of the old wiring replaced, so some of the K&T is “live” and some is not. And, rarely, all the old knob and tube is still in use. 

   The name comes from the white porcelain insulating knobs and tubes (shown above) used to mount and protect the single-insulated wires. K&T was the most cost-effective way to wire a home from about 1880 through the 1930s, before being gradually phased out in the 1940s.

Fuse Panels 

Screw-in type fuse panels are another old-time technology that insurance companies frown upon—besides being unsafe by today’s standards. Virtually all 1920s homes have had an electrical service upgrade by now, and a new circuit breaker panel has been installed as the main panel. But an old fuse-type panel might remain in service as a subpanel, and it may be located out-of-sight, like behind the refrigerator in the kitchen or under a picture frame in the hall. 

Ungrounded Receptacles 

Homes built during this era also had two-slot receptacle outlets. The third, round slot that we are used to seeing today may be missing at some locations. It has been required by the building code since the early 1960s for connecting a grounded three-prong electric appliance cord. Although not all modern electrical appliances have a three-prong cord that requires a three-slot outlet, many do.

    There may also be a few receptacles with non-polarized slots that are both the same size, like the example at right. Polarized receptacles have one slot taller that the other, so that the hot and neutral prongs can only be inserted one way. Most new cords have polarized prongs.   

    Two-slot receptacles are acceptable to continue using where a ground connection does not exist at the receptacle, as long as only two-prong cords for lamps, and other appliances that do not require grounding, are plugged into them. Unfortunately, this is also indicative that there is still some active K&T wiring.

    But here's the rub: lots of electric appliances used today have cords with three prongs. Using an adapter, like the one shown above, is not a safe solution to the dilemma. Theoretically, if the metal ring at the two-slot side of the adapter is connected to the securing screw for the receptacle cover plate, then the ground slot is connected to a ground. But that is almost never the case and most people don’t even bother connecting it—with the result that an appliance that requires grounding to be safe is ungrounded. Look for this behind the refrigerator and washing machine. 

   Even worse is a defect that we sometimes see in older homes, where the old ungrounded receptacle is changed out for a three-slot receptacle but there is no ground connection made. A three-light circuit tester is used by many home inspectors to check for this safety defect.

Not Enough Wall Receptacles

It is not unusual to find only one receptacle per bedroom and none in the dining room or hallways in 1920s homes. Extension cords snaking around the walls behind the furniture is one sign of this problem. Also, the bathroom may not have a receptacle at all because it was originally part of the light over the sink, which has since been replaced with a modern fixture. More circuits and receptacles are necessary for our homes filled with electric gadgets today.

No Ground Fault Circuit Interrupters (GFCIs

This leaves you without modern shock-protection in the wet areas of the home, like the kitchen and bathroom.

Undersized Electrical Service

When a 1920s family only used electricity for a refrigerator, a radio, maybe a water heater, and a few lights around the home, the size of the electric service coming into a home was smaller. Service is rated in amps, which is a measure of the amount of current flow/workload the system can handle. The standard was 60-amps. An electric meter for 60-amp service is shown below.

    Today most residential electrical service is 150 or 200-amps, in order to accommodate the major electric appliances: range, water heater, air conditioner, furnace, washer, dryer, and dishwasher, just to name a few. If you want all the modern appliances in your older home, you may have to upgrade the electric service. To learn more, see our blog post How can I find out the size of the electric service to a house?

Inadequate Insulation 

Vintage homes were built with non-insulated single-pane windows and no, or not much, wall and floor insulation. Minimal attic insulation that has compressed and deteriorated over the years, losing a significant portion of it’s original R-value, along with deteriorated or missing insulation on ducts can also contribute to higher utility bills.
    Air leaks around door and window openings due to deteriorated caulk may need to be repaired. While most older homes have had new attic insulation retrofitted at some point, floor insulation in houses with elevated floors is rare, like in the bare underside of an old house wood floor shown below, and wall insulation—because of the difficulty to install—almost never happens.

Asbestos Insulation 

We are all familiar today with the danger of asbestos. It can increase the chance of developing lung cancer and mesothelioma, but back then it was a wonder material. Loose-fill insulation was used in homes between the mid-1920s and 1950. Asbestos insulation should be left undisturbed until it can be removed by a qualified professional, as its fibers can be inhaled when they are airborne, creating a significant health hazard. Asbestos siding and roofing, while not a threat as long as the materials remain undisturbed, also require removal by a qualified, professional asbestos mitigator when it’s time for replacement.

    While loose-fill asbestos insulation represents a greater risk, the more common type of asbestos insulation found in older houses is vermiculite, which contains asbestos fibers in the material. Zonolite was the most popular brand, and it was sold in the U.S. up from the 1940s until 1990. Although not available when a 1920s home was originally constructed, it was often installed a few decades later. Vermiculite insulation is sometimes concealed under newer fiberglass batt insulation, like in the photo below. To read more about it, see our blog post Why is vermiculite attic insulation a problem for both buyers and sellers of a home?

Older HVAC Systems 

This also contributes to low energy efficiency in an older home. An older central air conditioning system has a SEER (energy efficiency) rating as low as 9. As the SEER number increases, the energy usage for the same amount of cooling drops proportionately. This means that a new 14 SEER system is about 50% more efficient. Newer gas furnace systems are also more energy efficient. Some homes may also have the original uninsulated metal ducts that were designed only for heating in an earlier era.

    Also, you may find an abandoned chimney peeking above the roof, but no fireplace in the home. See our blog post Why does the house have a chimney but no fireplace? for the answer to that mystery. Or a fireplace, but no chimney.

Buried fuel oil tanks 

They are often abandoned and forgotten when homeowners switch to newer fuel sources. Long-term corrosion causes tanks to leak into the surrounding soil, and poses a safety hazard. Disposal guidelines typically call for removal of the tank or filling it with sand and gravel. Soil testing may also be necessary to determine if the tank has leaked underground. A buried fuel tank has a fill pipe and a vent pipe, like in the picture below, except that the fill pipe cap is missing in this photo.


This toxic metal was once commonly used to make household paint and plumbing fixtures. While it has been banned in new construction for many years, lead-based paint and plumbing that aren’t removed may present a significant health hazard. Homes constructed prior to 1978 may contain lead paint (although use was significantly reduced after 1960), which can be ingested by small children or contaminate surrounding soil and vegetable gardens. It is easily identifiable by its alligator-like flaking pattern.

Lead Water Pipe

    Lead pipes, too, were still used in homes in the 1920s and they may allow lead to leach into drinking water. Lead pipe can be identified by its dull gray color and the ease by which it can be scratched by keys or coins.

Galvanized Steel Water Pipe 

Galvanized water pipe was used from the last half of the 1920s through the 1970s. Unfortunately, it has only a 40 to 50 year lifespan due to corrosion. It’s easy for a home inspector to locate and show you bubbling rust scars on old galvanized piping, but the real problem is on the inside of the pipes where loose flakes of rust accumulate behind fixture valves and cause reduced water flow. Eventually, the pipes rust through from the inside-out and begin to spring leaks. Also, many insurers will not issue a policy on a home with galvanized steel water supply piping.

Cast Iron Drain Pipe 

Cast iron was used up until about 1975, when it was replaced by the newer plastics like ABS and PVC. It has an average lifespan of approximately 60 to 70 years and corrosion holes cause leakage of sewage at the end of its lifespan, typically along the bottom surface, and allow tree roots into the system.

Foundation Problems 

Pier settlement and wall cracks are more prevalent in older homes simply because the soil underneath them has had more time to move. Additional temporary piers may have been added to remedy sagging floors. And trees have grown large in the yard over the years, with roots extending under the home that may have created additional foundation defects.

No Smoke Alarms 

They were not required in an earlier era, and some homeowners have neglected to install this very important safety device. 


   While a ‘20s era home may still have a couple of these issues, only a few will have most of them. Look closely for what upgrades have been done over the years and, if the house suits your taste, we say "go for it!"  

    Older homes also have some advantages to consider. See our blog post Why is buying an old house sometimes the best choice? for details.

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   One final note: your insurance agent will likely request a four point inspection report (also sometimes called a 4-point letter) in order to issue insurance. It’s a standard requirement for homes over 30-years old. The four points are 1) roof, 2) plumbing, 3) electrical, and 4) heating/air conditioning. Because older homes statistically tend to have more insurance claims related to the deteriorated condition of their components, insurance companies want to be sure that the home has been maintained over the years. Your home inspector can provide this additional report for you and, more importantly, can advise at the time of your home inspection if any conditions observed would be a “red flag” in the insurance 4-point inspection. See our blog posts How do I get my home ready for a four point inspection? and How do I get insurance if my home can't pass a 4-point inspection? for more.

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     To read about issues related to homes of particular type or one built in a specific decade, visit one of these blog posts:

What are the common problems of 1930s houses?

What are the common problems to look for when buying a 1940s house?

What are the common problems to look for when buying a 1950s house?

What are the common problems to look for when buying a 1960s house?

• What are the common problems to look for when buying a 1970s house?

What are the common problems to look for when buying a 1980s house?

What are the common problems to look for when buying a 1990s house? 

• What are the common problems to look for when buying a house built in the 2000s? 

• What are common problems found at a one-year warranty inspection of a new house?

What problems should I look for when buying a country house or rural property? 

What problems should I look for when buying a house that has been moved?

What do I need to know about buying a foreclosure? 

What should I look for when buying a former rental house?  

What problems should I look for when buying a house that has been vacant or abandoned?

What are the most common problems with older mobile homes?

What should I look for when buying a house that is being "flipped" by an investor seller? 

What do I need to know about a condo inspection?

What are the "Aging In Place" features to look for when buying a retirement home?

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