Jessica I. Marschall, CPA, ISA AM, President MAS LLC, Probity Appraisal Group and The Green Mission Inc.
Introduction
The valuation of materials and fixtures within real estate depends heavily on their attachment to the property versus their status as detached personal property. This principle is crucial in real estate appraisals, taxation, insurance, and donation valuations, particularly in the context of deconstruction and salvage. When components remain attached as part of an improvement, they typically carry higher value due to their contribution to the real estate’s utility, marketability, and financing potential. However, once removed, their value often declines due to depreciation, secondary market limitations, and diminished functionality in a different setting.
Understanding how much of a home’s total cost each component represents sharpens this analysis considerably. National construction cost data (most notably the National Association of Home Builders’ (NAHB) long-running Cost of Constructing a Home survey series) allows appraisers, accountants, and property owners to quantify the embedded cost of each building system while it is part of the real estate, and to contrast that figure with what the same component can command once detached. This updated article incorporates that data, including a component-by-component percentage breakdown of construction cost, the IRS authority supporting proportional basis allocation, and a worked application to a specific property.
1. The Real Estate Attachment Principle
Real estate is defined not only by the land itself but also by the improvements affixed to it, including buildings, structures, and fixtures. Real property encompasses these improvements and is often valued as a cohesive whole, taking into account factors such as location, utility, and contribution to income generation.
Value When Attached to Real Estate:
- Integrated Contribution: Components like kitchen cabinets, flooring, HVAC systems, and built-in appliances are integrated into the property’s function and aesthetic appeal. Their value is assessed as part of the whole, contributing to the overall market value of the real estate. The scale of this contribution is substantial: interior finishes alone, such as cabinets, countertops, flooring, drywall, appliances, and fixtures, represent roughly 24% of total construction cost, the single largest category in the NAHB survey.
- Marketability & Financing: Fixtures included in real estate transactions add to the appraised value, qualifying for mortgage financing and being included in property insurance coverage.
- Functional Value: Attached elements maintain a level of functional efficiency, ensuring they work seamlessly with the rest of the property’s infrastructure (e.g., a built-in refrigerator designed for a specific kitchen layout).
2. The Detachment Principle: Loss of Value Upon Removal
Once removed from the property, these same components lose their real estate designation and become personal property, leading to a reduction in their market value.
Value When Detached as Personal Property:
- Depreciation & Condition Changes: Once detached, fixtures and materials experience immediate depreciation due to handling, transportation, and storage risks. Many components cannot be reinstalled without damage or require retrofitting in a new environment.
- Loss of Financing & Insurance Benefits: Detached items are no longer included in real estate appraisals or eligible for traditional property financing. They must be sold in secondary markets, often at a fraction of their original cost.
- Narrower Market Demand: The market for detached materials is far more limited. While homeowners and builders may be interested in reclaimed materials, most buyers seek new, warrantied products. This shrinks the demand pool, reducing resale values.
3. What It Costs to Build a Home: Component Shares of Construction Cost
The most authoritative data on where construction dollars go comes from the NAHB’s Cost of Constructing a Home survey, conducted periodically since 1998. The most recent iteration, based on a 2024 survey of approximately 4,000 U.S. home builders, found that the average single-family home contained 2,647 square feet and cost $428,215 in construction costs alone, approximately $162 per square foot, the highest level recorded in the series’ history. Construction cost represented 64.4% of the average final sale price of $665,298.
The table below breaks out the general components of a home as a percentage of total construction cost, using the NAHB 2024 stage-of-construction framework. These are the figures cited, in adapted form, by Family Handyman, Reynard Design, and the Total Construction Kansas infographic listed in the sources.
Table 1. General Components of a Home as a Percentage of Total Construction Cost (NAHB 2024)
Several observations from these data merit emphasis:
- Interior finishes dominate. At 24.1% of construction cost, interior finishes are the largest single category; cabinets and countertops, at roughly $19,000 per home, are the largest individual line item within them. Notably, these are precisely the components most frequently recovered in deconstruction projects.
- The three major systems are nearly equal. Electrical, plumbing, and HVAC each average approximately $27,000 per home, together comprising about one-fifth of construction cost.
- Shares shift with material markets. In the NAHB’s 2022 survey, framing accounted for 20.5% of construction cost ($80,280 of a $392,241 total), reflecting the period’s extraordinary lumber price volatility; by 2024 framing had receded to 16.6% while interior finishes and major systems grew. Percentage allocations should therefore be matched to the construction era of the home being analyzed.
- Rules of thumb corroborate the survey data. Industry guidance (RBA Home Plans) places hard costs at 60-75% of an overall project budget: site work and foundation 10-15%, framing and structure 15-20%, exterior finishes 15-20%, major mechanical/electrical/plumbing systems 10-15%, and interior finishes 20-25%, with soft costs (design fees, permits, inspections) adding 10-15% and a recommended contingency of 5-10%.
Construction cost is only part of what a buyer ultimately pays. The composition of the average new-home sale price provides useful context:
Table 2. Composition of the Average New Single-Family Home Sale Price (NAHB 2024)
4. Case Study: Comparing the Value of Key Components
5. Market Differences Between Real Estate Fixtures & Salvaged Personal Property
A. Real Estate Market Advantages
- Higher Valuation: The value of fixtures is embedded in the real estate price, making them easier to finance and sell as part of the whole.
- Uniform Market Standards: Appraisers use established methodologies (e.g., comparable sales, cost approach) to assess value.
- Buyer Expectations: Homebuyers expect certain fixtures to be included in the property price, often paying a premium for move-in-ready features.
B. Salvage & Secondary Market Challenges
- Lower Demand & Price Sensitivity: Salvaged materials compete with new materials that offer warranties and standardized dimensions.
- Storage & Logistics Costs: The resale value must account for costs associated with transportation, warehousing, and condition degradation.
- Lack of Standardized Valuation: Unlike real estate, personal property lacks a uniform appraisal methodology, making valuation subjective and highly variable.
6. Applying Component Cost Percentages in Cost Basis and Appraisal Analysis
The component percentages in Table 1 have direct practical application for accountants and appraisers. When a taxpayer’s records do not itemize the original cost of individual building systems, nationally published component shares provide a defensible, documented framework for allocating a home’s cost basis among its major systems; for example, in analyzing partial dispositions, casualty losses, insurance schedules, or the residual basis of improvements removed during renovation or deconstruction.
Several sources of IRS authority support this type of proportional allocation. IRS Publication 551, Basis of Assets, directs that when multiple assets are acquired for a lump sum, basis is allocated among them in proportion to their respective fair market values. Treasury Regulation section 1.168(i)-8, which governs dispositions of MACRS property, permits a taxpayer making a partial disposition election to determine the unadjusted depreciable basis of the disposed portion using any reasonable, consistently applied method where specific cost records do not exist, expressly contemplating pro rata and cost-estimation approaches. And the IRS Cost Segregation Audit Techniques Guide (Publication 5653) describes the methodologies the Service itself considers acceptable for allocating building costs among component systems, including approaches built on published cost-estimation data. Together, these authorities make clear that a documented, proportional allocation of improvement cost across building systems, grounded in published national data such as the NAHB survey, is a recognized and defensible analytical framework.
The same data also quantify the article’s central thesis. A component’s embedded cost while attached, for example, the roughly $19,000 average investment in cabinets and countertops, sets a ceiling that its detached fair market value almost never approaches. Secondary-market pricing for salvaged cabinetry routinely runs at a small fraction of embedded cost, and the gap widens for labor-intensive systems (framing, drywall, rough-ins) whose cost is predominantly installation labor that cannot be recovered at all. The percentage breakdown thus serves two functions simultaneously: it documents how much value each component contributes to the improvement, and it disciplines expectations about what that component is worth once severed from it.
useful. It is not tax advice.
7. The Role of Deconstruction & Donation in Valuation
One area where salvaged materials retain meaningful value is in charitable donation appraisals. Under IRS guidelines, taxpayers may deduct the fair market value of salvaged building materials donated to qualified nonprofits. However, even in this context, materials are typically valued significantly lower than their original acquisition cost, reflecting the reality of the secondary market value rather than their replacement cost in a real estate setting.
IRS Considerations for Donated Materials:
- The fair market value is based on comparable sales in the used materials market, not the cost of new materials (see IRS Publication 561, Determining the Value of Donated Property).
- Condition, desirability, and resale potential determine valuation, which is often significantly lower than original cost.
- Appraiser qualifications and adherence to IRS guidelines (e.g., Form 8283 for non-cash donations over $5,000) are critical in ensuring defensible valuations.
8. Conclusion: Understanding the Economic Implications
The distinction between real estate fixture value and salvaged personal property value has significant implications for homeowners, investors, appraisers, and sustainability advocates. When part of real estate, materials and fixtures retain higher economic value, marketability, and financing advantages and, as the NAHB data demonstrate, each major building system represents a quantifiable share of the hundreds of thousands of dollars invested in constructing the improvement. However, when removed, they become personal property with a lower resale market, logistical challenges, and different valuation principles.
Understanding this principle is essential for those engaged in deconstruction, appraisal, tax planning, and circular economy efforts. While salvaged materials may not retain their original real estate value, their contribution to waste diversion, sustainability, and tax incentives provides compelling reasons for their responsible recovery and reuse.
Sources
- National Association of Home Builders (NAHB), “Cost of Constructing a Home in 2022,” Special Study, February 2023. https://www.nahb.org/-/media/NAHB/news-and-economics/docs/housing-economics-plus/special-studies/2023/special-study-cost-of-constructing-a-home-2022-february-2023.pdf
- National Association of Home Builders (NAHB), Eric Lynch, “Cost of Constructing a Home in 2024,” Special Study, January 2025. https://www.nahb.org/news-and-economics/housing-economics-plus/special-studies/special-studies-pages/cost-of-constructing-a-home-in-2024
- Family Handyman, “Here’s How Much It Costs to Build a Home in the U.S. Today” (analysis of the NAHB 2024 builder survey). https://www.familyhandyman.com/article/home-building-costs-survey/
- Reynard Design, “The Anatomy of a Home Build: A Detailed Cost Breakdown.” https://www.reynard.design/post/the-anatomy-of-a-home-build-a-detailed-cost-breakdown
- Total Construction Services of Kansas, “Infographic: The Cost of Building a New Home in the U.S.,” May 15, 2025.
Infographic: The Cost of Building a New Home in the U.S.
- RBA Home Plans, “Your Guide to Construction Cost Breakdown.” https://www.rbahomeplans.com/post/your-guide-to-construction-cost-breakdown
- Internal Revenue Service, Publication 561, “Determining the Value of Donated Property.” https://www.irs.gov/publications/p561
- Internal Revenue Service, Publication 551, “Basis of Assets.” https://www.irs.gov/publications/p551
- Treasury Regulation § 1.168(i)-8, “Dispositions of MACRS Property” (Electronic Code of Federal Regulations). https://www.ecfr.gov/current/title-26/section-1.168(i)-8
- Internal Revenue Service, “Cost Segregation Audit Techniques Guide,” Publication 5653 (June 2022). https://www.irs.gov/pub/irs-pdf/p5653.pdf