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Our research sources

Sources and References

Find the primary documents used across our guides. Each article also links the sources relevant to that topic.

government guidance

Protect Your Family from Exposures to Asbestos

U.S. Environmental Protection Agency · United States; homeowner planning and professional roles, with applicable state and local requirements verified separately

Last accessed 2026-09-06

government guidance

How to Clean Up After Rodents

Centers for Disease Control and Prevention · United States; disturbance precautions and contamination scope, not a site-specific cleanup procedure

Last accessed 2026-09-06

government guidance

Well-Insulated and Sealed Attic

ENERGY STAR / U.S. Environmental Protection Agency · United States; conditional retention and contractor planning, subject to material-specific hazards and the selected assembly

Last accessed 2026-09-06

government guidance

InfoTechnology: Bridge Moisture Content Measurement

U.S. Department of Transportation / Federal Highway Administration · United States; timber moisture measurement principles and limitations, excluding bridge-specific thresholds, probe dimensions, and inspection prescriptions

Last accessed 2026-09-06

government guidance

Above Deck Rigid Foam Insulation for Existing Roofs

U.S. Department of Energy / Pacific Northwest National Laboratory · United States; described retrofit assembly, not a universal exterior-insulation ratio or local code approval

Last accessed 2026-09-06

government guidance

Below Deck Spray Foam Insulation for Existing Roofs

U.S. Department of Energy / Pacific Northwest National Laboratory · United States; complete roof-retrofit planning with local adoption and exact-product conditions reviewed separately

Last accessed 2026-09-06

government guidance

Attic Knee Walls

U.S. Department of Energy / Pacific Northwest National Laboratory · United States; whole-boundary concepts, not generic foam thickness specifications

Last accessed 2026-09-06

government guidance

Air Sealing Attic Access Panels/Doors/Stairs

U.S. Department of Energy / Pacific Northwest National Laboratory · United States; access closure continuity and operability, subject to exact assembly details

Last accessed 2026-09-06

government guidance

Insulating Attic Kneewalls, March 2011

U.S. Department of Energy / Pacific Northwest National Laboratory · United States; historical conceptual brief, relevant primary excerpts checked; no savings or numeric code targets adopted

Last accessed 2026-09-06

official standard portal

Evaluation Reports Program

ICC Evaluation Service · Report scope and conditions of use; local approval remains separate

Last accessed 2026-09-06

official standard portal

16 CFR 460.20: R-value per inch claims

Electronic Code of Federal Regulations / Federal Trade Commission · United States; provision text checked September 6, 2026, not individualized legal advice

Last accessed 2026-09-06

official standard portal

16 CFR 460.12: Labels

Electronic Code of Federal Regulations / Federal Trade Commission · United States; provision text checked September 6, 2026, not individualized legal advice

Last accessed 2026-09-06

government guidance

Board Foot

Virginia Department of Forestry · Customary volume-unit definition; wood-measure context, not a foam-yield guarantee

Last accessed 2026-09-06

government guidance

Radon in Homes, Schools and Buildings

U.S. Environmental Protection Agency · United States; testing and repeat testing after relevant building changes

Last accessed 2026-09-06

government guidance

Moisture Metrics

DOE Building America Solution Center · Moisture definitions and vapor-pressure transport; no generic design target inferred

Last accessed 2026-09-06

government guidance

Lead-Safe Renovations for DIYers

U.S. Environmental Protection Agency · United States; residential renovation lead precautions

Last accessed 2026-09-06

official standard portal

Sound Transmission Class

Acoustical Society of America · Acoustical standards terminology; laboratory and field distinction

Last accessed 2026-09-06

manufacturer document

Acoustical Assemblies, SA200

USG · United States; manufacturer assembly guidance, not independent material ranking

Last accessed 2026-09-06

government guidance

Isocyanates (archived)

National Institute for Occupational Safety and Health (CDC) · United States workplaces; archived occupational-health overview

Last accessed 2026-09-06

government guidance

Isocyanates: Overview

Occupational Safety and Health Administration · United States workplaces

Last accessed 2026-09-05

official standard portal

ICC Digital Codes

International Code Council · Model codes; local adoption varies

Last accessed 2026-09-05

official standard portal

29 CFR 1910.134: Respiratory Protection

Occupational Safety and Health Administration · United States workplaces; applicable industry and state-plan rules matter

Last accessed 2026-09-05

government guidance

Unvented, Insulated Crawlspaces

DOE Building America Solution Center · United States; local code, flood and pest conditions apply

Last accessed 2026-09-05

government guidance

Air Sealing Attached Garage

DOE Building America Solution Center · United States; attached garages

Last accessed 2026-09-05

What a source does not establish

A federal guide does not determine your adopted local code. A manufacturer document applies only to the identified formulation and conditions. A model-code portal does not show every local amendment. A citation supports the linked claim, not every possible application.