Lime and Gypsum Product Manufacturing (U.S.) — NAICS 3274

A rollup primer for public- and private-market investors. NAICS (the North American Industry Classification System) code 3274 is a four-digit "industry group" that bundles two separate manufacturing industries — the plants that fire limestone into lime, and the plants that turn gypsum rock into drywall and plaster. Each child is itself a single-child pass-through to a six-digit leaf (327410 and 327420), so the leaf primers hold the company-by-company detail. This page synthesizes the two children and adds the group's own federal statistics; it does not re-derive the leaf-level detail.

---

1. Overview

NAICS 3274 groups two industries that share one recipe and almost nothing else. Both take a common mineral, calcine it — heat it in a kiln to drive off water or carbon dioxide (CO₂) — and sell the result as a bulk industrial or building input. That is why the classification files them together. But their customers, cycles, and competitive maps barely overlap:

• Lime (NAICS 32741) heats high-purity limestone into quicklime and hydrated lime. Buyers are steelmakers, power plants, water utilities, road builders, and chemical plants. Demand is driven by heavy industry and environmental rules [1][30].
• Gypsum products (NAICS 32742) heat and form gypsum rock into wallboard ("drywall," "Sheetrock," "plasterboard"), plaster, and joint compound. Buyers are homebuilders, remodelers, and commercial contractors. Demand is driven by the construction cycle [2][31].

For an investor, the useful way to hold 3274 in your head is two regional-commodity manufacturing businesses under one label — each a capital-heavy, freight-limited processor with local pricing power, but pointed at different ends of the economy. The most valuable thing this rollup can do is show how the two differ, so the rest of this page leads with that contrast — and then names the one force that now runs through both of them.

---

2. What's inside — the two children and how they differ

The group has exactly two children, and they are genuinely different businesses. Both are individually concentrated, both are mostly private or foreign-owned, and both sit behind a freight moat — but their size, direction of travel, customers, trade exposure, and feedstock story diverge sharply.

(CR4/CR8 = combined revenue share of the four and eight largest firms; HHI = Herfindahl-Hirschman Index, a 0–10,000 concentration score. Child figures from the leaf primers [30][31].)

The one-line read. Gypsum is the bigger business — about three-quarters of the group's revenue, employees, and payroll — and it rises and falls with housing. Lime is the smaller quarter, but it is where the momentum and the deal-making are. One nuance the revised children sharpen: lime's momentum is a price story, not a volume story. U.S. lime output has fallen since 2022 even as average plant value nearly doubled, so the industry's revenue growth rests on a price level that has to hold [1]. Gypsum, meanwhile, is working through a volume dip with prices softening at the margin [11]. Same kiln, opposite risk profiles: gypsum is a bet on the U.S. construction cycle; lime is a bet on heavy industry plus tightening environmental regulation. A holder of the whole group is diversified across two cycles that do not peak together — with the one shared exposure described in §6.

A word on plant economics. Gypsum plants are bigger by output — roughly $53M of shipments per establishment versus about $30M for lime — and lime firms tend to run more plants each (93 establishments across 29 firms, versus 172 across 95). Both are automated and capital-heavy: revenue per worker runs ~$680k in lime and ~$800k in gypsum. Read the establishment counts with care in both children, because they overstate the number of real production sites: the U.S. Geological Survey (USGS) counts 70 primary lime kiln plants plus 11 hydrating plants against Census's 93 lime establishments [1][5], and Eagle Materials counts six U.S. wallboard manufacturers running 59 plants and 69 production lines against Census's 172 gypsum establishments [12]. The comparison that follows is striking: gypsum earns roughly three times lime's revenue from a broadly similar number of production plants.

---

3. Size of the group (rollup figures)

Our ingested federal statistics for NAICS 3274 — the sum of its two children — are below. The two-child totals reconcile exactly to the group figures (265 establishments, 15,543 employees, 124 firms, $11.95B receipts), which is the useful check on a rollup.

Why the group looks less concentrated than either child — an important trap. The group's CR4 of 64.7%, CR8 of 86.3%, and HHI of 1,246.8 sit in "moderately concentrated" territory and look tamer than each child's numbers, which are now nearly identical to one another: CR4 82.6% and HHI 1,931 in lime, CR4 84.1% and HHI 1,934.6 in gypsum, with CR8 of 94.6% and 96.1% respectively [4][30][31]. That is a statistical artifact, not a competitive fact. Because lime and gypsum serve entirely separate customers, pooling two concentrated-but-unrelated markets into one four-digit aggregate dilutes the measured concentration — no single firm is large across both, so the combined leaderboard looks more crowded than either real market is. The 3274 HHI understates the market power buyers actually face. For any antitrust or pricing-power judgment, use the child-level figures (§8), not the group's.

There is no physical rollup — only a dollar one. The two children are measured in incompatible units: lime trades in tons at roughly $265 a ton, gypsum wallboard in thousands of square feet at an average net price of $226.08/MSF at Eagle [1][11]. Dollars are the only common denominator at this level, which is why every physical figure on this page stays attached to its child. The federal government does not treat the two as one market either — the Small Business Administration sets different small-business thresholds for them, 1,050 employees in lime and 1,500 in gypsum [6].

Undercount / coverage caveat. Coverage here is good, not thin: this is a group of large, mostly corporate manufacturers, so federal business statistics capture it well, and undercount from tiny sole proprietors or nonemployers — the blind spot in fragmented industries — is minor. Two narrower caveats do apply, in opposite directions:

• Lime is understated on the physical side. A meaningful share of lime is made captively — consumed on-site by the plant that makes it (kraft pulp-and-paper mills regenerate lime in recovery kilns; some sugar refiners and steel mills burn their own) and buried in another industry's statistics. USGS reports that 8 of its 24 lime companies produce strictly for internal use, and puts 2025 U.S. lime output near 15 million tons worth about $4.0 billion — larger than the Census merchant receipts partly for this reason and partly from the price spike since 2022 [1].
• Gypsum's dollar figure is a factory-gate number. Private research firms quote a larger "U.S. gypsum board market" (commonly $12–16B) because they bundle in distribution margins, related products, and sometimes installation, all of which sit outside NAICS 32742. The ~$9B here is the manufacturing industry itself [4][29].

Neither caveat is a small-operator or government-owned blind spot; both are about where the boundary is drawn, not missing firms. A related point applies to firm counts on the lime side, where Census (29 firms, 93 establishments, 2022–23) and USGS (24 companies, 70 kiln plants, 2025) disagree because they use different definitions, years, and scopes — two views of the same small population, not an error to reconcile [1][4][5].

---

4. Investable universe — where value concentrates

Across both children, the striking common feature is that most of the value is privately or foreign-held, and public exposure is scarce and always diversified. But the two differ in exactly one respect that matters to a stock-picker: lime has a listed pure-play and gypsum does not.

Lime (the smaller, hotter quarter). One genuine U.S.-listed pure-play — United States Lime & Minerals (Nasdaq: USLM), roughly $3 billion of market capitalization on $372.7 million of 2025 revenue, debt-free, high-margin, dividend-paying, but closely controlled and single-region [9]. Everything else is private or foreign: Belgium's Lhoist and Carmeuse, Canada's Graymont, and private-equity-backed Mississippi Lime hold most U.S. capacity [22][30]. The diversified listed proxy is Martin Marietta (NYSE: MLM), an aggregates major that agreed in June 2026 to buy Lhoist North America and become the largest U.S. lime-and-limestone producer [1][7][8][30]. Imerys and the other aggregates majors carry only partial or incidental exposure [30].

Gypsum (the larger, mature three-quarters). No pure-play at all. The U.S. leader United States Gypsum (USG / "Sheetrock") is owned by Germany's Knauf [23]; National Gypsum ("Gold Bond") and Georgia-Pacific Gypsum (Koch Industries) are private; CertainTeed Gypsum belongs to France's Saint-Gobain (Euronext Paris: SGO; U.S. OTC: CODYY) [24]; PABCO is a private regional. The only U.S.-listed name with material direct wallboard economics is American Gypsum, a segment of Eagle Materials (NYSE: EXP) — which sold about 2.76 billion square feet of wallboard in fiscal 2026, but whose wallboard and recycled-paperboard "Light Materials" arm is under half of Eagle's ~$2.3 billion of revenue; the rest is cement and aggregates [11][12][31].

The pattern for allocators. In both children the "listed way in" is really a diversified aggregates/building-materials major — Martin Marietta for lime, Eagle Materials for gypsum — plus foreign parents traded overseas. The direct owners of the pure economics are a short list of private and foreign industrial groups: on the lime side USGS's last named ranking put Lhoist North America, Graymont, Carmeuse Americas, Mississippi Lime, Martin Marietta Magnesia Specialties, and USLM as the first six producers, with ten companies accounting for 91% of U.S. output [22]. Tickers, scale figures, and ownership histories are in the two child primers.

---

5. How the money works

Both children run the same playbook — a regional commodity with a freight moat — so the money mechanics rhyme, with two divergences: the cost stack, and what utilization actually does.

Shared logic. Each product is heavy and cheap per unit, so freight destroys margin beyond a few hundred miles. The magnitudes are comparable: delivered freight can top 25% of the price in lime [21], and Eagle books $51.00/MSF of freight against $226.08/MSF of average net wallboard price, with under 5% of volume moving by rail [11]. Plants therefore serve a local radius, each region has only a few suppliers, and that geography — not brand — creates pricing power when demand is firm. Profit turns on energy (the calcining kiln is gas/coal/coke-intensive) and on controlling the feedstock — a permitted mineral reserve beside the plant with decades of life. None of the specialized frameworks for other sectors apply: this is unregulated industrial manufacturing, so there is no regulated-utility rate base, no real-estate FFO, and no mining all-in-sustaining-cost math to model [30][31].

Where they diverge — the cost stack.

• Lime burns high-purity limestone at roughly 2.77 million Btu per ton, with energy at 25%+ of production cost, and releases ~0.75–0.79 ton of CO₂ per ton of lime from the chemistry itself (calcination) — about two-thirds of a plant's emissions, unavoidable regardless of fuel. That is a structural carbon exposure but also a candidate for subsidized carbon capture [21][30].
• Gypsum layers paper facing (about one-third of wallboard production cost) and joint-compound chemistry on top of the mineral, with natural gas running roughly 8–10% of production cost, and faces a feedstock transition: as coal plants retire, the cheap "synthetic" gypsum they supplied is shrinking, pushing producers toward mined and imported natural rock [11][12][31].

Where they diverge — what utilization does. The old framing on this page treated both as classic high-fixed-cost businesses where volume absorbs overhead. The revised gypsum child forces a correction: Eagle discloses that fixed costs are less than 20% of overall wallboard cost [13], so slack utilization moves realized price — regional discipline — far more than it moves unit cost. In lime the conventional absorption story still holds. Utilization matters in both, for different reasons.

What advantaged assets earn. USLM reported 2025 revenue of $372.7 million, gross profit of $182.4 million (~48.9%), and operating profit of $157.9 million (~42.4%), with revenue up 17.3% on 11.7% higher volume and 5.6% higher prices, no debt, and reserve lives of about 17 to more than 80 years [9]; its Texas kilns draw cheap Permian-area gas at the Waha hub, worth an estimated ~$23 million to 2025 results [10]. Lhoist North America showed $1.75 billion of 2025 revenue and $786 million of adjusted EBITDA — a 45% margin — in transaction materials, though that carries company-defined adjustments and is not directly comparable with GAAP operating margin [8]. On the gypsum side Eagle's wallboard segment earned $286.8 million of operating profit on $764.5 million of revenue in fiscal 2026, roughly a 38% segment operating margin, down from 41% as volumes and prices softened [11]. Treat all of these as the potential of well-placed assets, not industry averages.

---

6. Demand drivers

This is where the two children most clearly hedge each other — and where they share one exposure.

• Lime tracks heavy industry and environmental rules. The last detailed federal breakdown (2021) ranks it: metallurgical uses 6.25 million tonnes, of which 5.25 million went to iron and steel; environmental uses 4.39 million (2.92 million for flue-gas treatment, 1.22 million for water treatment); chemical and industrial 3.27 million; and construction 2.08 million, of which 1.64 million was soil stabilization [14]. Steel and construction are cyclical; environmental and water demand is steadier and grows when regulation tightens, giving producers a buffer [1][30].
• Gypsum tracks construction across three end-markets that don't peak together: new residential (the swing factor), repair-and-remodel (the ballast), and nonresidential (offices, schools, hospitals, warehouses, data centers). Housing-linked demand dominates — Eagle estimates residential plus repair-and-remodel was more than 80% of calendar-2025 U.S. wallboard sales [11] — and the near-term cycle is soft, with May 2026 U.S. housing starts at a 1.177 million seasonally adjusted annual rate, 8.7% below May 2025 [28].

The one force that runs through both — coal retirement. The revised children make explicit something the group level should say plainly: the retirement of U.S. coal-fired power hits lime on the demand side and gypsum on the supply side. For lime, the shift away from coal generation has already eroded utility flue-gas-desulfurization volumes — the second-largest environmental use — and significant new U.S. coal capacity is unlikely [9]. For gypsum, that same fleet supplies the synthetic gypsum that was about 34% of U.S. supply in 2024 and is shrinking [2]; retirements slowed to 2.6 gigawatts in 2025 [20], but the direction of travel is one way. This is the group's genuine common thread, and it is not a hedge — it works against both children at once, if in different registers.

Net effect at the group level. Outside the coal channel, lime's regulatory tailwind and gypsum's housing cyclicality are driven by different forces, so a downturn in one end-market does not automatically hit the other — the rollup remains more demand-diversified than either child alone.

---

7. Regulation

Regulation is double-edged for both children, but in different registers.

• Lime. As an emitter, lime kilns fall under the Clean Air Act — the U.S. Environmental Protection Agency's (EPA) National Emission Standards for Hazardous Air Pollutants (NESHAP) for Lime Manufacturing (40 CFR part 63, subpart AAAAA), tightened in July 2024 to add limits on four previously unregulated pollutants (hydrogen chloride, mercury, total organic hazardous air pollutants, and dioxin/furans) [15], plus greenhouse-gas reporting under 40 CFR part 98, subpart S [16]. The footprint is documented: 68 lime reporters emitted 25.6 million tonnes of CO₂-equivalent in 2023 [17]. EPA estimated $484 million of control capital and roughly $167 million of annual cost (2022 dollars) and modeled a 5.5% price increase and 1.4% output decline — modeled effects, not observed outcomes, and EPA acknowledged it lacked lime-specific elasticity estimates [14]. EPA announced in March 2025 that it would reconsider several air rules, so the compliance trajectory retains policy uncertainty [18]. Because ~0.75–0.79 ton of CO₂ per ton is released by the chemistry itself, lime is also exposed to future carbon pricing [21]. As a beneficiary, tighter air, drinking-water, and wastewater rules increase lime demand — regulation is both a cost and a customer.
• Gypsum. Demand is shaped by building and fire codes, which push toward higher-spec, higher-margin panels (fire-rated "Type X," moisture/mold resistance); calcining-kiln and dryer air permitting applies, along with mine reclamation and process-water obligations. One correction the revised child supplies: EPA's Coal Combustion Residuals (CCR) rules govern the power-plant gypsum stream, but EPA excludes encapsulated beneficial reuse such as wallboard from federal CCR disposal regulation [19] — so the supply risk reaches producers through utility compliance costs and plant closures, not through a rule aimed at the panel makers. Antitrust scrutiny follows from high concentration: In re: Domestic Drywall Antitrust Litigation (MDL 2437, E.D. Pa.) swept in USG, National Gypsum, CertainTeed, Eagle/American Gypsum, PABCO and others over alleged 2011–12 price-fixing, with USG settling for roughly $48 million across purchaser classes without admitting liability [25].

---

8. Consolidation

Each child is, on its own, one of the more concentrated manufacturing industries the Census tracks — top-four shares of 82.6% in lime and 84.1% in gypsum, HHIs of 1,931 and 1,934.6 — and both got there the same way: large deals by deep-pocketed, mostly foreign or diversified owners [4]. In lime the whole national industry is 29 firms, and 50 firms account for 100% of receipts; in gypsum the top eight take 96.1% [4].

• Gypsum was consolidated by Knauf's ~$7B acquisition of USG (2019) [23] and Saint-Gobain/CertainTeed's ~$1.4B purchase of Continental Building Products (2020) [24], leaving a mature oligopoly competing on cost position rather than price wars [31].
• Lime's defining event is fresher and larger: Martin Marietta's June 27, 2026 agreement to buy Lhoist North America for $13.5 billion ($7 billion cash plus $6.5 billion stock), set to make it the largest U.S. lime-and-limestone producer and bringing more than 2 billion tons of reserves — roughly a 200-year life. The disclosed price equates to about 15 times 2025 adjusted EBITDA including expected run-rate synergies, a national-scale strategic multiple that should not be read across to smaller regional plants. The deal is subject to regulatory review and expected to close in the second half of 2026 [7][8].

As §3 warned, the group's CR4 (64.7%) and CR8 (86.3%) read as milder than reality because they pool two non-competing markets; the child-level figures — and regional markets that are often effective duopolies once freight is accounted for — are the true competitive picture [4][30][31]. Barriers to entry (permitted reserves, kiln capital, air permits) are steep in both; new national entrants are essentially unheard of. Expect further consolidation and more antitrust attention on the lime side in particular.

---

9. Risks

Shared across the group: energy-price swings (fuel is a large share of cost in both); freight inflation that can shrink each plant's serviceable radius and, on delivered-price contracts, stay with the producer; antitrust exposure given regional concentration; thin or absent public float, so most equity value is unreachable through listed markets; and — the newly explicit common exposure — coal-plant retirement, which erodes lime's flue-gas demand and gypsum's synthetic feedstock simultaneously [2][9][20].

Lime-specific: steel and construction cyclicality in its biggest end-markets, with the 2008–09 and 2019–20 volume declines as the template [14]; carbon and compliance costs from unavoidable process CO₂, including the 2024 NESHAP tightening's estimated $484 million of industry control capital [14][15]; a price-led revenue base — volumes have fallen while prices roughly doubled since 2022, so a reversion in price is the sharper risk to earnings than a volume shortfall [1]; application-specific substitution (crushed limestone, cement-kiln dust, fly ash, magnesium hydroxide), riskiest where a customer needs only alkalinity or bulk stabilization [14]; permitting, variable stone chemistry, and costly kiln outages [9]; single-asset/regional exposure for smaller producers; and, for the one pure-play, a closely held, illiquid float [9].

Gypsum-specific: housing and mortgage-rate cyclicality (the biggest swing factor, as the 2024–25 volume decline showed) [2][3][28]; a shrinking synthetic-gypsum supply forcing a shift to mined and imported rock [2]; import dependence at ~15% net import reliance, concentrated in Spain, Mexico, and Canada [2]; overcapacity risk — with utilization near three-quarters, a demand shock pressures price rather than unit cost [2][3][13]; and customer and channel concentration, a risk earlier versions of this page missed: three customers were roughly 64% of Eagle's fiscal-2026 wallboard segment sales [11], and distribution has consolidated into the big-box retailers, with GMS now inside Home Depot's SRS [26] and Foundation Building Materials bought by Lowe's for $8.8 billion in October 2025 [27].

Because the two sets of risks are otherwise driven by different cycles, the main group-level risks are the common ones: a broad industrial-plus-construction recession that hits steel, housing, and commercial building at once, and the coal-fleet retirement that touches both children from opposite sides.

---

10. How to invest & outlook

The routes, side by side. There is no clean way to buy "NAICS 3274" — you assemble exposure from the children:

• Lime: USLM (Nasdaq) as the sole listed pure-play, and Martin Marietta (NYSE: MLM) as the diversified way to own the sector's emerging leader once the Lhoist deal closes [7][8][9][30].
• Gypsum: Eagle Materials (NYSE: EXP) as the closest listed wallboard name (though majority cement/aggregates), and Saint-Gobain (SGO; U.S. OTC: CODYY) for its CertainTeed unit. No pure-play exists [11][24][31].
• Both: most capacity is private or foreign, so direct access runs through building-products/aggregates majors, private equity, and the feedstock layer (limestone and gypsum quarrying), where reserve quality, permits, fuel flexibility, and delivered-market radius matter more than nameplate capacity [30][31].

One route has closed. The gypsum distribution channel is no longer the clean back-door play it was: with GMS now inside Home Depot/SRS and Foundation Building Materials inside Lowe's, drywall distribution is a small piece of two large retailers rather than a set of standalone listed proxies [26][27].

The forward judgment. NAICS 3274 is two freight-moated, capital-heavy, mostly-private manufacturing industries filed under one code. Gypsum is the larger business — still earning roughly 38% segment operating margins at the one listed proxy — whose fortunes ride the U.S. housing cycle and a structural raw-material shift away from coal-derived rock, with the open question being whether a consolidated field holds price through the current soft patch. Lime is the smaller business with the stronger momentum — environmental regulation is a growing customer, prices have roughly doubled since 2022 even as volumes fell, and a $13.5 billion deal at about 15 times EBITDA just repriced the whole industry upward. Owned together, they diversify a single owner across two cycles that rarely peak in sync — with coal retirement the one force that pushes on both at the same time. For most investors the honest conclusion is the same on both sides: this is a group where ownership, not trading, is how the money is made — and the public market offers only a narrow, diversified window onto it. For the full company detail, cost math, and citations, read the two child primers, 32741 Lime and 32742 Gypsum Products.

---

Sources

Drawn from the two child primers (NAICS 32741 and 32742) plus this level's ingested federal statistics.

1. U.S. Geological Survey, Mineral Commodity Summaries 2026 — Lime (production, prices, company and plant counts, trade, captive production), 2026. https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lime.pdf
2. U.S. Geological Survey, Mineral Commodity Summaries 2026 — Gypsum (consumption, crude production, synthetic share, import reliance and sources), 2026. https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gypsum.pdf
3. U.S. Geological Survey, Mineral Commodity Summaries 2025 — Gypsum (2024 baseline volumes), 2025. https://pubs.usgs.gov/periodicals/mcs2025/mcs2025-gypsum.pdf
4. U.S. Census Bureau, 2022 Economic Census — Concentration Ratios & Selected Statistics (NAICS 3274 and children: receipts, firms, CR4/CR8/CR20/CR50, HHI). https://www.census.gov/programs-surveys/economic-census.html
5. U.S. Census Bureau, County Business Patterns 2023 (NAICS 3274 and children: establishments, employment, payroll). https://www.census.gov/programs-surveys/cbp.html
6. U.S. Small Business Administration, Table of Small Business Size Standards (NAICS 327410 = 1,050 employees; 327420 = 1,500 employees), 2023. https://www.sba.gov/document/support-table-size-standards
7. Martin Marietta Materials, Martin Marietta to Combine with Lhoist North America in $13.5 Billion Transaction (announced June 2026; $7B cash + $6.5B stock), IR News Release, 2026. https://ir.martinmarietta.com/news-releases/news-release-details/martin-marietta-combine-lhoist-north-america-135-billion
8. Martin Marietta Materials, Form 8-K and Transaction Presentation (Lhoist NA 2025 ~$1.75B revenue / ~$786M adjusted EBITDA / 45% margin; 2B+ tons of reserves; ~15x EV/EBITDA with synergies), SEC EDGAR, 2026. https://www.sec.gov/Archives/edgar/data/916076/000095015726000758/ex99-2.htm
9. United States Lime & Minerals, Inc., 2025 Form 10-K (revenue $372.7M; gross profit $182.4M; operating profit $157.9M; reserve lives; risk factors; flue-gas demand commentary), SEC EDGAR, 2026. https://www.sec.gov/Archives/edgar/data/82020/000110465926020480/uslm-20251231x10k.htm
10. Macrotrends, United States Lime & Minerals Gross Margin and related USLM analysis (Waha gas advantage), 2025. https://www.macrotrends.net/stocks/charts/USLM/united-states-lime-minerals/gross-margin
11. Eagle Materials Inc., Form 10-K, Fiscal Year 2026 (wallboard segment revenue and operating profit; net price and freight per MSF; volumes; customer concentration; end-market mix), SEC EDGAR, 2026. https://www.sec.gov/Archives/edgar/data/918646/000119312526230979/exp-20260331.htm
12. Eagle Materials Inc., Fourth Quarter and Fiscal Year 2025 Results (Light Materials/Gypsum Wallboard segment; U.S. wallboard plant and line counts; paper and energy cost shares), 2025. https://ir.eaglematerials.com/news-releases/news-release-details/eagle-materials-announces-fourth-quarter-and-fiscal-year-2025
13. Eagle Materials Inc., Form 10-Q, September 2025 (fixed costs less than 20% of wallboard cost), SEC EDGAR, 2025. https://www.sec.gov/Archives/edgar/data/918646/000119312525258663/exp-20250930.htm
14. U.S. EPA, Regulatory Impact Analysis: NESHAP for Lime Manufacturing Plants Technology Review (2021 end-use breakdown; compliance costs and modeled price/output effects; substitutes; historical cyclicality), June 2024. https://www.epa.gov/system/files/documents/2024-06/ria_lime_manufacturing_neshap_final_2024.pdf
15. U.S. EPA / Federal Register, NESHAP: Lime Manufacturing Plants Technology Review (final rule adds HCl, mercury, organic HAP, and dioxin/furan limits), July 16, 2024. https://www.federalregister.gov/documents/2024/07/16/2024-14692/national-emission-standards-for-hazardous-air-pollutants-lime-manufacturing-plants-technology-review
16. U.S. EPA / eCFR, 40 CFR Part 98, Subpart S — Lime Manufacturing (greenhouse-gas reporting), current. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-98/subpart-S
17. U.S. EPA, GHGRP Minerals Profile (68 lime reporters, 25.6M tCO₂e in 2023), 2024. https://www.epa.gov/ghgreporting/ghgrp-minerals
18. U.S. EPA, Lime Manufacturing Plants NESHAP (rule status; March 2025 reconsideration announcement), current. https://www.epa.gov/stationary-sources-air-pollution/lime-manufacturing-plants-national-emission-standards-hazardous
19. U.S. Environmental Protection Agency, Coal Combustion Residuals Reuse (encapsulated beneficial reuse excluded from federal CCR disposal regulation), accessed 2026. https://www.epa.gov/coal-combustion-residuals/coal-combustion-residuals-reuse
20. U.S. Energy Information Administration, 2025 Coal-Capacity Retirements, 2025. https://www.eia.gov/todayinenergy/detail.php?id=67427
21. European Lime Association (Ecofys), A Competitive and Efficient Lime Industry (energy ~25%+ of cost; ~2.77 MMBtu/ton; ~0.79 tCO₂/t process emissions ≈ 65% of total; freight >25% of price), 2019. https://www.eula.eu/wp-content/uploads/2019/02/A-Competitive-and-Efficient-Lime-Industry-Technical-report-by-Ecofys_0.pdf
22. U.S. Geological Survey, 2019 Minerals Yearbook — Lime (named producer ranking; top-10 companies = 99% of commercial sales, 91% of output), 2021. https://pubs.usgs.gov/myb/vol1/2019/myb1-2019-lime.pdf
23. USG Corporation / Knauf, Knauf Completes Acquisition of USG Corporation (~$7B), 2019. https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/news/19-04-24-knauf-completes-aquisistion-of-usg.pdf
24. Saint-Gobain / CertainTeed, Saint-Gobain Completes Acquisition of Continental Building Products (~$1.4B), 2020. https://www.saint-gobain-northamerica.com/company/newsroom/news-releases/saint-gobain-moves-forward-acquisition-continental-building-products
25. Top Class Actions, Drywall Price-Fixing Class Action Settlement (In re: Domestic Drywall Antitrust Litigation, MDL 2437, E.D. Pa.), 2016. https://topclassactions.com/lawsuit-settlements/lawsuit-news/drywall-price-fixing-class-action-settlement/
26. The Home Depot, Home Depot and Its Subsidiary SRS Distribution Complete Acquisition of GMS, 2025. https://corporate.homedepot.com/news/company/home-depot-and-its-subsidiary-srs-distribution-complete-acquisition-gms
27. Lowe's Companies Inc., Lowe's Completes Acquisition of Foundation Building Materials ($8.8B; SEC Form 8-K), October 2025. https://www.sec.gov/Archives/edgar/data/60667/000006066725000199/exhibit991-10092025.htm
28. U.S. Census Bureau, New Residential Construction, May 2026 (housing starts). https://www.census.gov/construction/nrc/current/
29. Private gypsum-board market estimates ($12–16B, distribution- and installation-inclusive): Grand View Research, U.S. Gypsum Board Market Size & Outlook, 2030, 2024, https://www.grandviewresearch.com/industry-analysis/us-gypsum-board-market-report; and Emergen Research, US Drywall & Gypsum Board Market Size, Growth Outlook 2034, 2024, https://www.emergenresearch.com/industry-report/us-drywall-gypsum-board-market
30. Histometrics — NAICS 32741 (Lime Manufacturing) child primer, including its private-producer profiles for Lhoist, Carmeuse, Graymont, and Mississippi Lime.
31. Histometrics — NAICS 32742 (Gypsum Product Manufacturing) child primer.