Research Methodology
Every guide on The Dwelling Index follows a structured research process. This page explains how we gather information, evaluate sources, label claims, and maintain accuracy across our content.
The Dwelling Index is an independent ADU research publication for homeowners. Our role is educational. We are not a lender, mortgage broker, attorney, architect, contractor, or builder, and our methodology is designed to help readers understand what is verified, what is estimated, and what still needs to be confirmed with the relevant city, agency, lender, or qualified professional.
Source Hierarchy
We prioritize sources in the following order:
- 1Primary government and regulatory sources — Legislation, enrolled bill text, municipal codes, planning department materials, agency handbooks, government-published data, and official program rules.
- 2Direct company disclosures — Official pricing pages, spec sheets, service-area pages, policy documents, financing-product materials, and other published information from the companies we evaluate.
- 3Published research — Peer-reviewed studies, government-commissioned reports, research from established institutions, and data from recognized housing or policy organizations.
- 4Verified secondary sources — Industry reporting and expert commentary used only to supplement primary-source research and only when cross-checked against more authoritative materials.
What We Treat With Extra Caution
We do not rely on press releases, promotional blog posts, anonymous forum claims, marketing copy, or unsourced comparison pages as primary evidence for legal, pricing, financing, or permitting claims.
If a claim cannot be supported by a sufficiently reliable source, we either qualify it clearly, label it as an estimate or editorial analysis, or leave it out.
What Our Labels Mean
Verified
The claim has been checked against at least one primary source and, where appropriate, cross-checked against an additional reliable source. The source is cited on the page.
Estimated
The figure or conclusion is based on available data but involves calculation, interpolation, comparison, or editorial judgment. The assumptions or basis for the estimate are explained where possible.
Last updated
The date when material changes were made to the page, such as new information, revised figures, updated rules, or added sections.
Last verified
The date when the editorial team most recently reviewed the page against current sources and confirmed that the published information remained accurate, even if no substantive edits were needed.
Research by Topic Area
Law & Policy Research
Primary Sources
- •State legislature databases and enrolled bill text
- •Municipal planning department zoning codes and ADU ordinances
- •Government agency guidance documents
- •Published regulatory analysis and official implementation materials
Process
We read the underlying legislation or code directly rather than relying on summaries of summaries. When a state passes new ADU legislation, we review the enrolled bill text, compare it against existing code where needed, and verify effective dates before publishing. We do not treat press coverage or vendor articles as primary support for legal claims.
Cost Research
Primary Sources
- •Published contractor pricing and company disclosures
- •Construction cost databases and industry pricing data
- •Government-published construction or housing data
- •Municipal fee schedules, permit fee tables, and impact-fee information
- •Verified cost case studies and project examples where available
Process
We verify cost figures against multiple data points before publication when possible. When we publish a cost range, we aim to explain what the figure represents — such as base price versus installed cost — and what is included or excluded. We avoid presenting a single cost figure without context when the underlying variables materially affect the outcome.
Prefab & Company Research
Primary Sources
- •Official company websites, pricing pages, and spec sheets
- •Public-facing policy, warranty, and service-area materials
- •Permit, licensing, or complaint information where publicly available
- •Direct company communications when used to verify factual details
Process
We evaluate prefab and ADU companies based on pricing transparency, published specifications, service-area clarity, publicly available business information, and homeowner-relevant decision factors. Comparisons are based on editorial criteria, not affiliate relationships. When company details change, we update pages as new information is verified.
Financing-Path Education
Primary Sources
- •Fannie Mae Selling Guide and Freddie Mac Seller/Servicer Guide materials
- •FHA and HUD handbooks or policy statements
- •CFPB consumer guidance
- •Agency and housing-finance program documentation
- •State or local housing finance authority materials where relevant
Process
We ground financing education in the underlying agency or program guidance that governs the option being discussed. We distinguish between broad eligibility frameworks, lender overlays, and program availability. We do not present a financing option as universally available, universally appropriate, or guaranteed to apply to a specific borrower.
How We Handle Time-Sensitive Topics
Some parts of ADU research change quickly. These include:
- State and local ADU laws
- Municipal zoning and permitting rules
- Prefab company pricing or service areas
- Financing program availability
- Agency guidance affecting mortgage or renovation products
For these topics, readers should verify details directly with the relevant city, county, lender, agency, or company before acting. Our role is to explain the landscape clearly, identify the main variables, and point readers toward the underlying sources.
Original Analysis and Added Value
The Dwelling Index is not built to simply repeat what already appears on search results pages.
Where possible, we add value through:
- Original comparison tables
- Worked examples
- Cost and tradeoff breakdowns
- Side-by-side analysis of financing or building paths
- Methodology notes
- Screenshots or source documentation
- Source-linked explanations written in plain language for homeowners
When a page includes editorial analysis, we aim to separate factual claims from interpretation and make the basis for our reasoning clear.
Review & Update Cadence
Every published guide is reviewed on a recurring basis. Topics in faster-changing areas — such as legislation, pricing, financing programs, and company details — are reviewed more frequently.
When a significant change occurs, such as a new law, updated agency guidance, or material pricing change, we prioritize reviewing the affected content and updating the page as needed. When appropriate, we note material updates directly on the page.
The “last verified” date shown on a page reflects the most recent date the editorial team checked the content against current sources and confirmed it remained accurate.
Corrections
If we discover a material error, we correct it promptly. When appropriate, we add a correction note or update note to the affected page so readers can understand what changed.
If you believe a page is inaccurate, outdated, or unclear, please contact us through our Corrections page and include the page URL and, if possible, the source you believe should be reviewed.