Asphalt Shingle and Coating Materials Manufacturing (NAICS 324122)

A Histometrics industry primer for public- and private-market investors

1. Overview

Almost four out of five American homes wear a roof of asphalt shingles, and the factories that make those shingles — plus the roll roofing, roofing cements, coatings, and saturated felts that go with them — are what the U.S. government files under NAICS (North American Industry Classification System) code 324122. It is a small, capital-intensive, highly concentrated corner of manufacturing: roughly 183 plants and about 11,300 workers producing an estimated $15.0 billion of shipments a year [1][2].

Investors care about this industry for one reason above all: it is unusually defensive for a building-products business. Most of its demand is replacement of worn-out or storm-damaged roofs rather than new construction, so it holds up far better than lumber, cement, or appliances when housing starts fall. Combine that with a tight oligopoly and you get some of the fattest, steadiest margins in all of building products — the roofing segment of the largest public player earned a 32% EBITDA margin in 2025 [8].

There are two ways in. The public route is narrow: one U.S. large-cap (Owens Corning), a French-listed parent (Saint-Gobain, which owns CertainTeed), and a newly spun-off building-products company (Amrize). The private route is where most of the industry actually sits — the single largest manufacturer, GAF, is privately held, as are IKO, Atlas, TAMKO, and PABCO. This is not an industry of tiny operators; it is a handful of giants, most of them private.

2. What it is, and how it's structured

Scope. NAICS 324122 covers establishments that (a) saturate purchased mats and felts with asphalt or coal tar, and (b) make asphalt shingles, roll roofing, roofing cements, coatings, and saturated boards and felts from purchased asphaltic materials [4]. The signature product is the fiberglass asphalt shingle: a fiberglass mat is saturated and coated with oxidized ("blown") asphalt, then surfaced with ceramic-coated mineral granules that give color and block ultraviolet light [16]. An ARMA environmental product declaration describes the sequence precisely: the manufacturer mixes oxidized asphalt with mineral filler, coats or impregnates a fiberglass web, applies colored mineral granules to the exposed surface and a parting agent to the reverse, adds sealant, and — on architectural shingles — laminates multiple layers before cutting and packaging [25].

The industry sits inside NAICS 3241, Petroleum and Coal Products Manufacturing — a reminder that its economics are tied to crude oil, because the asphalt binder is a byproduct of petroleum refining [16].

What it excludes (important, because "roofing" is spread across many codes):

• NAICS 324121 — Asphalt Paving Mixture and Block Manufacturing (road paving asphalt, the same feedstock, a different product).
• NAICS 324110 — Petroleum Refineries, which produce the asphalt flux (bitumen) that these plants buy as raw material. Census assigns integrated refineries that both refine crude and make roofing products to 324110, not 324122 [26].
• NAICS 238160 — Roofing Contractors, the crews who install roofs (a service, not manufacturing, and a far larger employment base).
• NAICS 423330 — Roofing, Siding & Insulation Merchant Wholesalers, the distributors (Beacon/QXO, SRS, ABC Supply) that sit between factory and contractor.
• Non-asphalt roofing: clay and concrete tile (NAICS 327), metal roofing (sheet-metal work, NAICS 332322), and synthetic/composite roofing (plastics, NAICS 326).

Ownership mix. Unusually top-heavy. A few large manufacturers — one U.S.-listed (Owens Corning), one foreign-listed parent (Saint-Gobain/CertainTeed), one newly public (Amrize/Malarkey) — sit alongside several large privately held firms: GAF (owned by Standard Industries), IKO, Atlas, TAMKO, and PABCO [9][12][14][15]. There is essentially no long tail of mom-and-pop shingle makers, because a modern line costs hundreds of millions of dollars and only pays off at scale.

Vertical integration. Integration differs materially by producer. GAF's parent also controls roofing-granule, glass-mat and logistics operations; IKO oxidizes asphalt, mines or processes mineral inputs, makes glass mat and produces some packaging internally; TAMKO likewise traces its integration back to an asphalt-oxidation plant and paper mill [27][28][29]. Integration protects availability and quality but raises capital intensity and exposure to plant utilization.

3. How big it is

Our federal figures (the authoritative U.S. numbers) for NAICS 324122:

A caveat on scope, not undercount. Because this is heavy manufacturing dominated by a few large firms — not a fragmented, cash, or government-run activity — federal business statistics capture it well; there is little hidden informal activity to undercount. The important nuance runs the other way: the Census $15.0 billion value of shipments covers everything these plants make (shingles plus roll roofing, cements, coatings, and felts), so it is larger than private "asphalt shingle market" estimates that count shingles alone (commonly put around $7–8 billion for the U.S. shingle segment) [5]. In physical terms, ARMA shipment data shows approximately 140 million U.S. shingle squares shipped in 2025, down from 161 million in 2024 and 169 million in 2023 (a "square" is 100 square feet of roof) [30]. Asphalt shingles hold about 59% of the total U.S. roofing market [6][7]. Also note the true "roofing economy" — the contractors and distributors — dwarfs this manufacturing code in jobs and revenue but lives under different NAICS codes (see Section 2).

4. The investable universe

Pure public plays are few; the biggest names are private. A clean map:

Adjacent public exposure for those who want the theme without a pure play: Amrize (AMRZ) and Saint-Gobain (SGO) are diversified building-materials companies where shingles are one slice; Carlisle Companies (NYSE: CSL) is mostly commercial single-ply roofing, not asphalt shingles; and the distribution layer is now investable through QXO (NYSE: QXO) — which acquired Beacon Roofing Supply for $10.6 billion in April 2025 and describes itself as North America's largest publicly traded distributor of roofing, waterproofing and complementary building products — and Home Depot (NYSE: HD), which owns distributor SRS [22][36]. Two manufacturers (GAF, Owens Corning) supply roughly 60% of the North American asphalt-shingle market between them [24].

5. How the money works

Owners of shingle plants make money on a handful of levers specific to commodity building-products manufacturing:

• Capacity utilization and freight economics. Shingles are heavy and low in value per pound, so they can only ship profitably a few hundred miles from the plant. Producers run regional networks and live or die on keeping lines full; fixed costs are high, so incremental volume drops quickly to the bottom line, and storm-driven demand spikes create powerful operating leverage. Plants usually operate continuous lines and warehouse finished production because customer delivery cycles are short [8].
• Input-cost pass-through. The bill of materials is roughly 60% fiberglass mat, 25% asphalt binder, and 15% minerals (limestone filler and ceramic granules) by volume [16]. Asphalt is an oil-refining byproduct, so margins hinge on the spread between shingle price and asphalt cost. In an oligopoly, the leaders have historically been able to push through price increases to protect that spread. Owens Corning's 2025 results illustrate the model: with volume down ~7%, $129 million of higher selling prices partly offset $52 million of input-cost inflation, $20 million of higher manufacturing costs and $7 million of higher delivery costs [8]. Rough 2023 input benchmarks: asphalt binder ~$450–550/ton, fiberglass mat ~$1,200–1,500/ton, granules ~$200–300/ton [17].
• Asphalt supply complexity. Roofing asphalt is a refinery residual that must meet specific softening and weathering properties, and refinery configuration and product choices affect its availability. Asphalt supply has at times been constrained, which is why IKO and others oxidize and store asphalt at their own plants [8][28].
• Vertical integration. The strongest players own their granule mines and asphalt-coating operations (CertainTeed runs three stand-alone granule plants, for example), insulating them from supplier margins and shortages [12].
• Mix / premiumization. The profit ladder runs from basic 3-tab shingles up to laminated ("architectural") shingles and then to premium designer, impact-resistant (Class 4), cool-roof, and solar-integrated products that carry higher prices and margins [19][23]. Shifting volume up this ladder is the main organic growth lever in a slow-growing market.
• Demand stability. Because ~80%+ of volume is re-roofing rather than new build, revenue is far less cyclical than most building products — the industry's single most attractive financial feature [7].

6. What drives demand

• Re-roofing dominates. Roughly four-fifths of shingle volume is replacement and repair, not new construction [7]. Saint-Gobain's 2023–2025 average for U.S. residential-roofing demand attributes 50% to renovation, 28% to weather and major storms, and 22% to new construction — explaining why roofing can outperform other residential building products during a weak housing cycle but underperform after an unusually quiet storm year [34]. Shingle roofs last about 15–25 years, so a huge installed base generates a steady replacement stream regardless of the housing cycle.
• Aging roofs. As of 2025, an estimated 38% of U.S. homes showed moderate-to-poor roof condition — a large latent replacement pipeline [20].
• Severe weather. Hail and wind are a major, lumpy demand source: severe convective storms drove more than $15 billion of roof-related insurance claims across Texas, Oklahoma, and Iowa in 2024–2025, and the number of states with widespread severe hail damage rose year over year [20]. Big storm seasons pull demand forward; quiet ones create air pockets. Owens Corning explicitly notes that storm damage can cause Roofing sales to depart from ordinary seasonal remodeling and new-construction patterns [8].
• Insurance behavior. Carriers are tightening acceptable roof ages (often to 15–20 years) and, in hail zones, pushing homeowners toward UL 2218 Class 4 impact-resistant shingles in exchange for premium credits — both of which convert into replacement contracts and richer mix [20]. Insurers may also raise deductibles, limit roof coverage or depreciate older roofs, reducing claim-funded replacement spending.
• Existing-home turnover and remodeling. Home sales and repair-and-remodel spending trigger discretionary roof replacement; higher mortgage rates that freeze turnover are a modest headwind.
• New residential construction. The smaller share of demand, and the cyclical part — this is what makes the industry less volatile than peers, not more.

7. Regulation

• Air emissions (federal). Asphalt processing and roofing plants are regulated under the EPA's NESHAP (National Emission Standards for Hazardous Air Pollutants) for Asphalt Processing and Asphalt Roofing Manufacturing, issued under Section 112 of the Clean Air Act. The rule requires maximum-achievable-control-technology limits on hazardous pollutants including formaldehyde, hexane, hydrogen chloride, phenol, and polycyclic organic matter; it was finalized in 2003 and reaffirmed after a 2020 risk-and-technology review. New, modified or reconstructed facilities are also subject to New Source Performance Standards (NSPS). Applicable operations include blowing stills, asphalt storage, saturators/coaters and mineral handling [18][37][38].
• Wastewater. EPA effluent guidelines govern total suspended solids, oil and grease, and pH for covered dischargers [39].
• Worker safety. OSHA (Occupational Safety and Health Administration) exposure limits govern asphalt fumes at the plant, though OSHA notes its standards do not specifically address asphalt fumes as a distinct substance [40]. BLS reported a 2024 total recordable injury-and-illness incidence rate of 2.0 cases per 100 full-time-equivalent workers for NAICS 324122 [41].
• Energy / "cool roof" codes. California's Title 24 building-energy standard, together with Cool Roof Rating Council (CRRC) solar-reflectance ratings and ENERGY STAR labeling, sets minimum reflectivity for many roofs and steers demand toward reflective "cool" shingles; qualifying products can unlock federal tax credits and utility rebates [19]. Standard asphalt shingles are relatively low-reflectance; specially coated granules can create "cool" shingles for hot climates, but reflective products have historically carried a premium and have less benefit in cold climates [42].
• Product performance codes. Building codes (IBC/IRC) reference wind-resistance standards (ASTM D7158/D3161) and, increasingly at the insurer level, UL 2218 hail-impact classes — de facto product requirements in storm-exposed markets [20].

Regulation here raises the cost of the coating process and pushes the product mix toward premium reflective and impact-rated goods; it is a moderate cost and, for the technology leaders, a mix tailwind.

8. Competitive dynamics and consolidation

This is a textbook oligopoly. Four firms account for 66.9% of shipments and eight for 83.7%; the HHI of 1,366 places it in the "moderately concentrated" band, but the top-heavy reality is closer to a three-to-five-player game (GAF, Owens Corning, CertainTeed, IKO, Atlas), with GAF and Owens Corning alone at roughly 60% of the North American shingle market [2][24]. Saint-Gobain describes CertainTeed as one of only three meaningful national roofing players, implying that GAF, Owens Corning and CertainTeed form the national top tier [34]. Entry barriers are high: line capital costs, freight-limited regional economics, secured granule and asphalt supply, and deep contractor brand loyalty. The scale required is illustrated by Owens Corning's planned Prattville, Alabama line — designed for roughly 6 million squares annually, representing a major, specialized asset investment [32].

Consolidation is playing out on three fronts:

• Manufacturing: Holcim's $1.35 billion purchase of Malarkey (2022), later folded into the Amrize spin-off (2025), added a fifth serious residential player [10][11].
• Distribution: the channel is consolidating even faster — QXO bought Beacon Roofing Supply for $10.6 billion in April 2025, and Home Depot bought SRS Distribution for ~$18 billion in 2024, leaving a distribution "Big 3" (QXO, SRS/Home Depot, ABC Supply) that increasingly shapes how shingles reach the roof [22][36].
• Adjacent tech: GAF Energy's nailable solar shingle and Saint-Gobain's shingle-recycling technology are attempts to extend the category and differentiate [23][12].

9. Risks

• Asphalt / oil-price volatility. The biggest variable cost is an oil derivative; a fast run-up in crude or refining spreads can compress margins faster than prices can be raised.
• Housing and rate cycle. The new-construction slice and remodel demand soften when mortgage rates are high and existing-home sales freeze.
• Storm variability. Weather-driven demand is lumpy — a mild hail season leaves capacity underused; the industry's best years follow catastrophic ones.
• Substitution. Metal, synthetic, tile, and low-slope single-ply membrane roofing take share at the premium and durability end, aided at times by tariffs and code changes. Asphalt retains a large installed base because it is comparatively affordable, widely distributed and familiar to contractors, but more resilient alternatives can gain share where insurance costs, wildfire rules, hail exposure or lifetime-cost considerations outweigh first cost.
• Input tariffs and supply. Tariffs on imported building materials and any disruption to granule, fiberglass, or asphalt supply pressure costs.
• Environmental and litigation exposure. Tightening air rules, plus a long history of product-warranty and defective-shingle class actions against major brands, are recurring legal and reputational risks.
• End-of-life and recycling. EPA estimated that approximately 15 million metric tons of asphalt shingles were discarded in the United States in 2018, of which approximately 13 million were landfilled and 2 million recovered. Contamination, collection economics and the aged binder in tear-off shingles complicate reuse, but manufacturers are developing routes to use reclaimed asphalt in paving or new roofing products [43].
• Installer labor. A shortage of roofing crews can throttle how fast replacement demand converts into shipments, capping volume in peak periods. This is a constraint at the contractor level (NAICS 238160), not manufacturing, but can constrain manufacturer sell-through.

10. How to invest, and the outlook

Public routes. The cleanest large-cap exposure is Owens Corning (OC), where roofing is the profit engine (32% segment EBITDA margin in 2025) [8]. Saint-Gobain (Paris: SGO; OTC: CODYY) offers CertainTeed exposure inside a diversified global materials group, and Amrize (AMRZ) offers Malarkey inside a North-American building-products company. For the picks-and-shovels of the value chain, QXO (distribution) and Home Depot (which owns SRS) capture the channel, and Carlisle (CSL) captures commercial roofing rather than shingles. Investors judging these names should look at roofing-segment operating margin, price/cost spread versus asphalt, volume in squares, and mix shift toward laminated/impact/solar products. Note that Owens Corning's roofing segment includes shingles but also roofing components, oxidized asphalt, glass mat, specialty veils and composite lumber — it is not a pure-shingle margin [8].

Private routes. Most of the industry is off the public market. The largest manufacturer, GAF/Standard Industries, and peers IKO, Atlas, TAMKO, and PABCO are privately held; direct access generally means private equity or private-credit vehicles, or investing one layer out — in roofing-contractor roll-ups (an active PE theme) and distribution. Carlyle's minority stake in TAMKO is a template for how outside capital typically participates [13]. Note that contractor rollups are installation-service investments under NAICS 238160, not investments in the manufacturing economics of 324122.

The outlook (forward-looking). The structural case is a durable re-roofing tailwind: a large, aging housing stock, insurers forcing earlier replacement, and severe-weather losses that trend higher over time should keep replacement volume growing at a low-single-digit pace even through housing downturns [6][20]. Premiumization — impact-resistant, cool-roof, and solar-integrated shingles — is the margin story on top of that. The principal swing factors to watch are asphalt (oil) costs against the industry's pricing discipline, the cadence of storm seasons, and continued consolidation in both manufacturing and distribution. On balance, this is a slow-growing, weather-lumpy, but high-margin and defensively positioned industry — attractive for its cash generation and stability rather than its top-line growth.

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Sources

1. U.S. Census Bureau — County Business Patterns, 2023 (NAICS 324122: establishments, employment, payroll). https://www.census.gov/programs-surveys/cbp.html
2. U.S. Census Bureau — Economic Census 2022: Concentration Ratios & Industry Statistics (NAICS 324122: receipts, firms, CR4/CR8/CR20/CR50, HHI). https://www.census.gov/programs-surveys/economic-census.html
3. U.S. Small Business Administration — Table of Small Business Size Standards, 2023. https://www.sba.gov/document/support-table-size-standards
4. U.S. Census Bureau / IBISWorld — 2022 NAICS Definition, 324122 Asphalt Shingle and Coating Materials Manufacturing, 2022. https://www.ibisworld.com/classifications/naics/324122/asphalt-shingle-and-coating-materials-manufacturing/
5. Mordor Intelligence — Asphalt Shingles Market Size, Share & Growth Trends, 2025. https://www.mordorintelligence.com/industry-reports/asphalt-shingles-market
6. Global Market Insights / The Freedonia Group — Asphalt Shingles Market Size, 2025–2034 (U.S. demand in squares), 2025. https://www.gminsights.com/industry-analysis/asphalt-shingles-market
7. Mordor Intelligence — United States Roofing Market (asphalt-shingle share; re-roof share), 2025. https://www.mordorintelligence.com/industry-reports/united-states-roofing-market
8. Owens Corning — Full-Year 2025 Results / Form 10-K (Roofing segment net sales ~$4.44B; EBITDA ~$1.41B; 32% margin; volume and cost dynamics). https://www.sec.gov/Archives/edgar/data/1370946/000137094626000067/oc-20251231.htm
9. Standard Industries — Who We Are / About (GAF, largest North American roofing manufacturer), 2025. https://www.standardindustries.com/who-we-are/about/
10. Holcim — Holcim to Acquire Malarkey Roofing Products for $1.35 Billion, 2022. https://www.holcim.com/media/media-releases/holcim-acquire-malarkey-roofing-products
11. Holcim / Amrize — Holcim Completes Spin-off of North America Business (Amrize, NYSE: AMRZ), 2025. https://www.holcim.com/media/media-releases/holcim-completes-spin-off-of-north-america-business
12. CertainTeed (Saint-Gobain) — Saint-Gobain Acquires Asphalt Shingle Recycling Technology / About (granule plants), 2023. https://www.certainteed.com/about/newsroom/saint-gobain-acquires-asphalt-shingle-recycling-technology-advancing-its-commitment
13. PE Professional — Carlyle Takes Minority Piece of TAMKO, 2019. https://peprofessional.com/blog/2019/03/29/carlyle-global-takes-minority-piece-tamko-2/
14. IKO Industries — Company Overview (family-run; 30+ North American and European plants), 2024. https://www.iko.com/na/
15. Asphalt Roofing Manufacturers Association (ARMA) — Asphalt Shingle & Roofing Manufacturers, 2024. https://www.asphaltroofing.org/asphalt-roofing-manufacturers/
16. Wikipedia / IKO — Asphalt Shingle (composition: fiberglass mat, oxidized asphalt, mineral granules), 2024. https://en.wikipedia.org/wiki/Asphalt_shingle
17. OpenPR / industry plant-cost study — Asphalt Roofing Shingles Manufacturing Plant Cost & Revenue (2023 raw-material price ranges; trade estimate), 2024. https://www.openpr.com/news/4287137/asphalt-roofing-shingles-manufacturing-plant-cost-revenue
18. U.S. Environmental Protection Agency — NESHAP: Asphalt Processing and Asphalt Roofing Manufacturing (2003 rule; 2020 risk-and-technology review). https://www.epa.gov/stationary-sources-air-pollution/final-rule-reduce-toxic-air-emissions-asphalt-processing-and
19. Atlas Roofing / GAF — California Title 24 Cool Roofing & CRRC/ENERGY STAR compliance, 2025. https://www.atlasroofing.com/california-title-24
20. Verisk — Roofing Reality Check: Risk Is Rising Even in Quiet Storm Years (roof condition, hail claims, insurer behavior), 2026. https://www.verisk.com/company/newsroom/roofing-reality-check-risk-is-rising-even-in-quiet-storm-years/
21. Insurance Journal — Roof Costs Soar Even as Claims Decline: Verisk (replacement cost ~$17,631), 2026. https://www.insurancejournal.com/magazines/mag-features/2026/06/22/874418.htm
22. QXO, Inc. — QXO to Acquire Beacon Roofing Supply (and Home Depot–SRS context), 2025. https://investors.qxo.com/news/news-details/2025/QXO-to-Acquire-Beacon-Roofing-Supply-for-11-Billion/default.aspx
23. GAF Energy — Timberline Solar ES 2 Energy Shingle, 2025. https://www.gaf.com/en-us/roofing-materials/residential-roofing-materials/shingles/gaf-energy-timberline-solar-roofing-system
24. Global Market Insights — Asphalt Shingles Market (GAF and Owens Corning ~60% of North American shingle market), 2025. https://www.gminsights.com/industry-analysis/asphalt-shingles-market
25. Asphalt Roofing Manufacturers Association (ARMA) — Environmental Product Declaration: Asphalt Shingles (manufacturing process), 2023. https://www.asphaltroofing.org/wp-content/uploads/2023/08/111.1_ARMA-Asphalt-Shingles.pdf
26. U.S. Census Bureau — NAICS 324122 Definition. https://www.census.gov/naics/resources/archives/sect31-33.html
27. GAF — Announces New Specialty Products and Services Business Unit (vertical integration), 2025. https://www.gaf.com/en-us/about-us/news-press-releases/2025/gaf-announces-new-specialty-products-and-services-business-unit
28. IKO Industries — What Sets Us Apart (vertical integration: asphalt oxidation, mineral inputs, glass mat), 2024. https://www.iko.com/na/blog/what-sets-us-apart-of-the-rest/
29. TAMKO — Our History (asphalt-oxidation plant and paper mill integration). https://www.tamko.com/about/our-history
30. Gibraltar Industries — Q1 2026 Presentation (ARMA shipment data: 140M squares 2025, 161M 2024, 169M 2023). https://www.marketscreener.com/news/gibraltar-industries-1st-quarter-2026-presentation-slides-ce7f58d3de8bf726
31. GAF — Company Profile (30 U.S. locations, 4,800+ employees). https://www.gaf.com/en-us/about-us
32. Owens Corning — Selects Prattville, Alabama as Location for New Shingle Plant (6M squares capacity, 17 U.S. plants by 2027). https://newsroom.owenscorning.com/all-news-releases/news-details/2025/Owens-Corning-Selects-Prattville-Alabama-as-Location-for-New-Shingle-Plant-in-the-Southeastern-U-S-/
33. CertainTeed — Locations (15 U.S. roofing-plant locations). https://www.certainteed.com/about-us/locations
34. Saint-Gobain — FY2025 Presentation (U.S. residential-roofing demand mix: 50% renovation, 28% weather, 22% new construction; CertainTeed as one of three national players). https://www.saint-gobain.com/sites/saint-gobain.com/files/media/document/CA-T1-2026_FY-2025_va.pdf
35. Atlas Roofing — New Horizons Press Release (Hood Companies subsidiary; 36 North American facilities). https://www.atlasroofing.com/asphalt-life/new-horizons-press-release
36. QXO — 2025 Form 10-K ($10.6 billion Beacon acquisition; largest publicly traded distributor). https://www.sec.gov/Archives/edgar/data/1236275/000162828026012601/qxo-20251231.htm
37. U.S. Environmental Protection Agency — Asphalt Processing and Asphalt Roofing Manufacturing NESHAP. https://www.epa.gov/stationary-sources-air-pollution/asphalt-processing-and-asphalt-roofing-manufacturing-national
38. U.S. Environmental Protection Agency — Asphalt Processing and Asphalt Roofing Manufacture New Source Performance Standards. https://www.epa.gov/stationary-sources-air-pollution/asphalt-processing-and-asphalt-roofing-manufacture-new-source
39. U.S. Environmental Protection Agency — Paving and Roofing Materials Effluent Guidelines. https://www.epa.gov/eg/paving-and-roofing-materials-effluent-guidelines
40. OSHA — Asphalt Fumes Overview. https://www.osha.gov/asphalt-fumes
41. U.S. Bureau of Labor Statistics — 2024 Incidence Rates of Nonfatal Occupational Injuries and Illnesses (NAICS 324122: 2.0 per 100 FTE). https://www.bls.gov/web/osh/table-1-industry-rates-national.htm
42. U.S. Department of Energy — Cool Asphalt Shingles Research. https://www.energy.gov/cmei/buildings/articles/cool-asphalt-shingles
43. U.S. Environmental Protection Agency — Asphalt Shingles End-of-Life Inventory (15M metric tons discarded 2018; 13M landfilled, 2M recovered). https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1014HPX.txt