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Ohio building history, hazards and the rules

Heating a Central Ohio house, era by era: coal, gas, furnaces and chimneys

A Central Ohio house built before about 1960 was designed around a fuel it no longer burns. This page sets that change out from the records that measured it: the Census Bureau's heating fuel tables for Ohio, Franklin County and Columbus, each with its own year and universe; the city's own account of when gas reached its streets and then its pipes; the smoke ordinance of 1913; and what Ohio's residential code asks of a furnace, a flue and a chimney. It says nothing about whether any of it is safe.

Last updated September 2026 · The Census Bureau's house heating fuel series and six decennial housing volumes, the American Community Survey's 2020 to 2024 estimates, the filed rules of the Residential Code of Ohio, the City of Columbus's own bulletin and the Franklin County Auditor's parcel record of August 15, 2026 were read September 2026 · No prices on this page; the Estimate Builder carries those · Part of the knowledge base

What this page measures, and what it does not

The Census Bureau asked what a house burned and published the answer state by state from 1940 to 2000, and asked separately, in 1940, what the house was heated with. Franklin County and Columbus come out of each decade's own volume, where the categories change every ten years, so every figure below carries its year, its universe and its place.

The Residential Code of Ohio is quoted from the state's own filed rules, in Ohio's numbering, which prints residential sections without the model code's letter prefix. This page says which rules are in force and what the record gives as their starting dates; it never says which code any one house was built under, and the page on which building code a house was built under takes that up on its own terms. Nothing here is a verdict: no sentence says a chimney, a flue or a furnace in anybody's house is safe or unsafe, and none says what to do about one.

The water heater is on the hot water page, the bathroom exhaust fan on the bathroom electrical page, the wiring on the wiring page, carbon monoxide alarms on the incidents page, and a basement below the sewer on the floods page.

The fuel, decade by decade

In 1940 the Census counted 1,867,501 occupied units in Ohio that reported a heating fuel, and coal or coke was the fuel in 88.5 percent of them. The national row in the same file is 54.7 percent. Electricity is missing from the 1940 row because, as the Bureau puts it, electricity as a heating fuel was so rare that its use was not counted.

Census yearOhio occupied unitsUtility gasCoal or cokeElectricityFuel oil or keroseneWood
19401,867,5017.4%88.5%Not counted1.0%3.0%
19502,272,56534.2%53.8%0.2%8.7%1.3%
19602,852,53367.3%14.8%0.4%15.2%0.4%
19703,289,43276.5%3.1%3.4%14.1%0.1%
19803,833,82871.0%0.8%13.0%10.8%1.4%
19904,087,54668.2%0.4%16.8%7.5%2.5%
20004,445,77368.8%0.1%18.3%4.7%1.1%

Two footnotes in the Bureau's files break the comparison across decades: utility gas and bottled gas were combined in 1940, and in 1950 electricity was tallied only for noncentral systems. The 1940 and 1950 files head the count column occupied units reporting heating fuel; from 1960 it is simply occupied units.

That series has no county row. In 1950 the Census counted 105,240 occupied units in the city of Columbus reporting heating equipment, 75,315 of them centrally heated, with coal the fuel in 43,295 of those against utility gas in 30,200.

From 1960 the volumes count all occupied units. In Franklin County utility gas heated 167,474 of 200,763 occupied units in 1960, 233,174 of 259,321 in 1970, 266,277 of 322,817 in 1980 and 297,926 of 378,723 in 1990, while coal or coke over those four counts fell from 15,248 to 2,128, then 446, then 115, and electricity climbed from 207 to 5,687, then 40,034, then 65,963. Columbus runs the same way: 125,104 of 142,378 occupied units on utility gas in 1960 with 11,083 on coal or coke, 161,313 of 173,173 in 1970 with 1,126, 184,281 of 217,151 in 1980 with 251, and 204,174 of 257,013 in 1990 with 52.

The 2000 report gives no coal figure for either place, because it collapses coal or coke, wood, solar energy and other fuel into one column: 1,346 county units in that column, out of 438,778 occupied housing units, with 343,836 on utility gas and 83,002 on electricity. The city's row reads 301,788 occupied housing units, 233,640 on utility gas and 62,583 on electricity.

The American Community Survey's five-year estimates for 2020 through 2024 then put 553,099 occupied housing units in Franklin County, an estimated 370,219 on utility gas, 169,515 on electricity and 61 on coal or coke, that last with a margin of error of 56. The city's estimate is 390,528 occupied housing units, 249,609 on utility gas, 133,066 on electricity and 16 on coal or coke. The survey defines utility gas as gas piped through underground pipes from a central system to serve the neighborhood.

What the 1940 count found inside the houses

Of 1,876,041 occupied units in Ohio that reported heating equipment in 1940, 1,127,300, or 60.1 percent, had central heating. Warm air was already the Ohio system: of those, a piped warm-air system served 881,687, steam or hot water 203,080 and a pipeless warm-air furnace 42,533. The other 748,741 units had no central heating at all, and 718,193 of them were heated by a heating stove. That is a larger denominator than the fuel table's 1,867,501: the two tables asked different questions.

For Columbus the same printed page counted 83,597 occupied dwelling units, and the Census's own percent column puts 68.6 percent of those reporting their heating equipment as centrally heated. The count behind that percentage does not print: one digit in the Columbus row of that scan reads as an 8 or as a 3, both readings foot exactly, and neither the number of city units with central heating nor the number reporting equipment can be settled. What is legible is the other half: 25,708 Columbus units had no central heating, 24,478 of them on a heating stove, and of those 25,708 units 19,163 burned coal or coke and 6,318 gas.

Where the coal came from, and how the gas arrived

The Ohio Department of Natural Resources' Division of Geological Survey, quoted by Ohio State University Extension, says the first reported production of coal in Ohio was in 1800. The department says coal is found in the eastern third of Ohio and that there are approximately 58 named coal seams in the state. Columbus sits in central Ohio, outside that eastern third, so the coal a Columbus house burned had to be shipped in. The Ohio Historical Marker at Nelsonville, in Athens County and outside Central Ohio, says the arrival of the Columbus and Hocking Valley Railroad in 1869 assured the town's prominence as a major shipping point of coal. The field that coal came out of, its company towns and the state's production series are on the page on the Hocking Valley coal towns that heated Columbus.

Gas came to the street long before it came to the furnace. The City of Columbus's own history says Columbus got its first streetlights in 1844, gas powered. The Columbus Metropolitan Library's digitized 1850-51 Columbus city directory records the Columbus Gas Light and Coke Company as chartered in February 1846 and organized on April 1, 1850; the directory gives the day as February 12 and Alfred E. Lee's 1892 history of the city gives the act of the General Assembly as February 21, so the month and the year print here and the day does not. Cleveland had a different company of nearly the same name in the same year, which Case Western Reserve University's Encyclopedia of Cleveland History dates to February 6, 1846 and calls an artificial-gas supplier. Nothing here merges the two or makes either the ancestor of a present-day utility.

Charter and gas are four years apart: the Columbus Gas Light and Coke Company was chartered in February 1846, and Lee's history says gas was first let into the pipes for private consumers on December 7, 1850. Natural gas took four more decades. The same history says natural gas in considerable quantity was discovered in the Clinton limestone at Thurston, Fairfield County, twenty-five miles southeast of Columbus, in May 1888, and dates the first natural gas burned in Columbus to December 31, 1889, when the Central Ohio Natural Gas and Fuel Company, incorporated that July, turned it on. An earlier prospecting company, the Columbus Natural Gas and Fuel Company, had transferred its rights and franchises to that one, and Lee names the two separately.

Congress passed the Emergency Natural Gas Act of 1977, Public Law 95-2, on February 2, 1977, and its list of high-priority uses begins with use of natural gas in a residence. The American Historical Association's magazine records that the Columbia Gas Company told Columbus City Schools in late January 1977 that the district's fuel allocation would be drastically reduced to conserve gas for residential use, and that its 96,000 students began School without Schools on February 7.

What a coal-heated city did about its smoke

The City of Columbus's own official publication, The City Bulletin, records that the city's smoke ordinance, No. 27,113, was passed on March 3, 1913, and describes it as providing for the inspection, regulation and abatement of smoke in the city of Columbus, Ohio, and the plants causing the emission of the same. The 1913 text itself was not found; what is in hand is the city's 1916 amending ordinance. What the ordinance measured was time: as amended in 1916, its section 13 limited the emission of dense smoke to no more than six minutes in any one hour from stacks of class I.

Somebody enforced it. Columbus had a smoke inspector who reported every year under section 20 of the city smoke ordinance, and by 1918 the office was printed in the city's annual reports as the Division of Smoke Abatement; the federal Bureau of Mines still listed a smoke inspector for Columbus, under the department of public safety, in 1939. It is a Division in every Columbus record read here and never a Bureau.

The rules a furnace, a flue and a chimney meet in Ohio today

The rule that keeps a gas appliance out of a bathroom sits in Ohio's fuel gas chapter, not its mechanical chapters. Section 2406.2 of the Residential Code of Ohio says appliances shall not be located in sleeping rooms, bathrooms, toilet rooms, storage closets or surgical rooms, or in a space that opens only into such rooms. It carries six exceptions. One is the closet a Central Ohio house often actually has: an appliance may sit in a space opening only into a bedroom or bathroom where the space is used for no other purpose, has a solid weather-stripped door with an approved self-closing device, and takes combustion air directly from the outdoors.

Section 2407.4 of the same chapter says that where exhaust fans, clothes dryers and kitchen ventilation systems interfere with the operation of appliances, makeup air shall be provided; the fan's own rules are on the bathroom electrical page. Ohio's heating and cooling chapter names a bathroom once, at section 1409.2: vented wall furnaces installed between bathrooms and adjoining rooms shall not circulate air from bathrooms to other parts of the building.

On the chimney Ohio is explicit. Section 1003.11 says masonry chimneys shall be lined, and section 1003.11.1 names four acceptable lining systems for residential-type appliances, beginning with clay flue lining complying with ASTM C315; the federal Department of Housing and Urban Development's rehabilitation guide, writing nationally, says older chimneys may be unlined and gives pre-1910 as the period. Where an appliance is connected to an existing chimney or vent, section 1801.3 asks that the chimney be resized as necessary, that its flue passageway be free of obstructions and combustible deposits, and that a masonry chimney have a cleanout.

Those chapters carry different starting dates in the state's own record, and the record is the rule number's rather than the requirement's. The general mechanical and fuel gas chapters each give May 27, 2006 as their earliest prior effective date; the chimneys and fireplaces, heating and cooling, combustion air, and chimneys and vents chapters each give January 1, 2013. All of them read effective July 1, 2019.

When the energy chapter arrived

Ohio's residential energy provisions are younger than the rest. The energy chapter is one rule, Ohio Administrative Code 4101:8-11-01, effective July 1, 2019, and its own record gives January 1, 2008 as its earliest prior effective date, about nineteen months after the mechanical and fuel gas chapters' own earliest date. The Ohio Board of Building Standards' own history of the Ohio Basic Building Code runs from July 1, 1979, when the Board adopted the 1978 BOCA building and mechanical codes, to July 1, 2007, and names building, mechanical and plumbing codes and no energy code at all.

What that chapter does first is sort the state by climate zone. Table 1101.7 puts Franklin County in zone 5A, and Ohio is not one zone: the same table puts Adams, Brown, Hamilton and Pike counties in 4A. Section 1101.7 says that zone is used for determining the applicable requirements in sections 1101 through 1111, and the values it indexes are on the page on how Central Ohio houses were built.

What the county's own parcel record holds

Filtered to property class R, land use codes 510 through 515, the primary dwelling card and a non-zero year built, the Franklin County Auditor's parcel record as downloaded on August 15, 2026 holds 297,465 single-family houses. Across every decade combined, 92.31 percent of those houses carry the auditor's HEAT value 2 - HEAT/AIR CON and 7.63 percent carry 1 - HEAT. The older houses hold the exception: 19.25 percent of those built before 1900 carry 1 - HEAT, against 87.53 percent of those built in the 1950s and 99.90 percent of those built in the 2000s carrying 2 - HEAT/AIR CON.

Read that field narrowly. It distinguishes heat from heat and air and nothing else, so it says nothing about fuel, furnace type or equipment, and it is the assessor's current record rather than the house as built: a 1920s house recorded as HEAT/AIR CON is describing what it has now, not what it was built with. The auditor defines none of these codes. Its Label Names workbook expands other abbreviations into plain English but expands HEAT to the same single word as the abbreviation, and the nearest thing to a published code table is the auditor's Parcel CSV description of fields, which lists three codes for a field it calls AIRCOND, 0 for none, 1 for heat and 2 for heat and air, the same three the HEAT field carries, although the auditor nowhere states the two fields are the same thing.

The fireplace fields are the assessor's recorded count of wood-burning openings and stacks, with a blank read as zero, confirmed on the auditor's own parcel pages. Across every decade combined, 43.49 percent of the county's single-family houses have at least one opening recorded. The peak by decade built is the 1970s at 66.51 percent; houses built before 1900 sit at 26.83 percent, lower than every decade from the 1920s through the 1990s despite being the oldest in the record. Houses built from 2020 through 2025, a partial decade, sit at 1.46 percent.

The short version. By the Census Bureau's own series, coal or coke was the fuel in 88.5 percent of the Ohio occupied units that reported one in 1940 and 0.1 percent in 2000. In Columbus, coal was the fuel in 43,295 of the 75,315 centrally heated units in 1950 and in 52 of 257,013 occupied units in 1990. Gas lit the city's streets from 1844; the first natural gas burned there on December 31, 1889.

Sources

Every figure, date and quotation on this page comes from one of these documents, read on the date given. Where two of them disagree, the page says so.

Common questions

When did Columbus houses switch from coal to gas?

The Census Bureau's own counts put it in the 1950s. In 1950 coal was the fuel in 43,295 of the 75,315 centrally heated occupied units in the city of Columbus, against utility gas in 30,200. By 1960, when the volume counts all occupied units instead, utility gas heated 125,104 of the city's 142,378 and coal or coke 11,083. Coal fell to 1,126 city units in 1970, 251 in 1980 and 52 in 1990, and the American Community Survey's estimate for 2020 through 2024 is 16.

When did natural gas first reach Columbus?

Alfred E. Lee's 1892 history of the City of Columbus dates the first natural gas burned in the city to December 31, 1889, when the Central Ohio Natural Gas and Fuel Company, incorporated that July, turned it on. The gas came from the Clinton limestone at Thurston, Fairfield County, twenty-five miles southeast of Columbus, where the same history says natural gas in considerable quantity was discovered in May 1888. Manufactured gas came far earlier: that history says gas was first let into the pipes for private consumers in Columbus on December 7, 1850.

Did Columbus have a smoke ordinance when the city burned coal?

Yes. The City of Columbus's own official publication, The City Bulletin, records that the city's smoke ordinance, No. 27,113, was passed on March 3, 1913, providing for the inspection, regulation and abatement of smoke in the city of Columbus, Ohio, and the plants causing the emission of the same. As amended in 1916, its section 13 limited the emission of dense smoke to no more than six minutes in any one hour from stacks of class I. A smoke inspector reported yearly under section 20, and by 1918 the office was printed as the Division of Smoke Abatement.

What climate zone is Franklin County in under Ohio's energy code?

Zone 5A. Table 1101.7 of the energy chapter of the Residential Code of Ohio, rule 4101:8-11-01, lists Franklin County in climate zone 5A, and section 1101.7 says the zone taken from that table or from Figure 1101.7 is used for determining the applicable requirements in sections 1101 through 1111. Ohio is not a single zone: the same table puts Adams, Brown, Hamilton and Pike counties in zone 4A. That chapter's own record gives January 1, 2008 as its earliest prior effective date.

Does the Residential Code of Ohio allow a gas appliance in a bathroom?

Section 2406.2 of the Residential Code of Ohio, in the fuel gas chapter, says appliances shall not be located in sleeping rooms, bathrooms, toilet rooms, storage closets or surgical rooms, or in a space that opens only into such rooms. The section carries six exceptions. One allows an appliance in a space opening only into a bedroom or bathroom where the space is used for no other purpose, has a solid weather-stripped door with an approved self-closing device, and takes its combustion air directly from the outdoors. Another covers a direct-vent appliance installed in accordance with its listing.

Does the Residential Code of Ohio require a chimney to be lined?

Section 1003.11 says masonry chimneys shall be lined, and section 1003.11.1 names four acceptable lining systems for residential-type appliances: clay flue lining complying with ASTM C315, listed and labeled chimney lining systems complying with UL 1777, factory-built chimneys or chimney units listed for installation within masonry chimneys, and other approved materials that will resist flue gases up to 1,800 degrees Fahrenheit. The federal Department of Housing and Urban Development's rehabilitation guide says older chimneys may be unlined and gives pre-1910 as the period, which is a national statement and not an Ohio one.

How many Franklin County houses still burn coal?

An estimated 61, with a margin of error of 56. That is the American Community Survey's five-year estimate for 2020 through 2024, out of 553,099 occupied housing units in Franklin County, of which an estimated 370,219 are heated by utility gas and 169,515 by electricity. The margin is nearly as large as the estimate, so the figure is small and uncertain rather than exact. For comparison, the 1990 Census counted 115 coal-heated occupied housing units in the county, and the city of Columbus's own estimate for 2020 through 2024 is 16.

How many Franklin County houses have a fireplace on the auditor's record?

Across every decade combined, 43.49 percent of the 297,465 single-family houses in the Franklin County Auditor's parcel record as downloaded on August 15, 2026 have at least one wood-burning fireplace opening recorded. The peak by decade built is the 1970s at 66.51 percent. Houses built before 1900 sit at 26.83 percent, lower than every decade from the 1920s through the 1990s, and houses built from 2020 through 2025 sit at 1.46 percent. The field is the assessor's recorded count of openings, not a count of working fireplaces.

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