# Project: ADU — Investment Summary & Cost / Value Analysis

# Hickory Run — ADU & Barn: Investment Summary

**7105 Guess Rd, Hillsborough NC 27278**  ·  Prepared for **Chris**  ·  October 3, 2026
*Cost, value, and what the numbers actually say — working numbers, not final quotes.*

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## Where the property stands today

| County record — PIN 0816-57-1049 | |
|---|---|
| Parcel size | 7.66 acres |
| Zoning / jurisdiction | RR, Durham County |
| Primary dwelling | 2,685 sf · 4bd/2.5ba |
| Built | 1973, brick ranch |
| Purchased | 03/19/2026 · $630,000 |

| Current county appraisal | |
|---|---|
| Land (7.66 ac) | $267,094 |
| Building | $352,358 |
| Outbuildings | $8,714 |
| **Total appraised** | **$628,166** |
| Annual county tax | $2,958 |

The county appraised the parcel at $628,166 in the same cycle it sold for $630,000 — within 0.3%. In this market area the county's numbers track real sale prices, which is why we're using them as the baseline rather than guessing.

## What we're building

- **ADU — 1,250 sf living** plus a **900 sf garage** (2,150 sf under roof) for Tim, with its own well, septic, and electric service.
- **Barn — 30×40 with lean-to**, roughly 1,680 sf under roof.
- **Solar — ~$35,000**, planned later, not part of the initial build.

**Sizing note:** Durham caps ADUs at 50% of the primary dwelling's heated area in the RR district on lots over 4 acres. At 2,685 sf primary, that cap is **1,342 sf** — so the 1,250 sf ADU is compliant, and well under the primary. Confirmed against the county record.

## What it costs

| Item | Scope | Low | High |
|---|---|---|---|
| **ADU + garage** | 1,250 sf living + 900 sf garage, own well/septic/electric | $215,000 | $260,000 |
| **Barn** | 30×40 + lean-to, ~1,680 sf under roof | $42,000 | $59,000 |
| **Solar** (later) | Owned system, no federal credit remaining | $35,000 | $35,000 |
| **Total investment** | | **$292,000** | **$354,000** |

ADU figure is Erin's current working cost. Per-square-foot check: $215–260k over 2,150 sf blended is **$100–121/sf**, or **$172–208/sf** if attributed to living space alone — both squarely inside the Durham range of $140–280/sf. The number is realistic, not optimistic.

## What it adds — property value

| Component | Added value | Basis |
|---|---|---|
| **ADU + garage** | +$210,000 – $270,000 | County's own cost rates: 1,250 sf living at ~$177/sf new, plus 900 sf garage |
| **Barn** | +$31,000 | 1,200 sf enclosed at $26/sf + 480 sf lean-to at open-shed rate |
| **Solar** (later) | modest, not counted | Owned solar adds some appraised value; kept out to stay conservative |
| **Total added** | **+$241,000 – $301,000** | |

**Projected property value after build: $869,000 – $929,000** (from $628,166 today).

## What it returns

> **The headline:** the ADU is roughly **break-even to slightly value-positive**. It is not a loss-maker, and it is not a profit centre. It is a house for Tim that pays for most of itself in property value.

| Scenario | Cost | Added value | Recovery |
|---|---|---|---|
| ADU + garage only | $215,000 – $260,000 | $210k – $270k | **81% – 126%** |
| ADU + solar | $250,000 – $295,000 | $210k – $270k | 71% – 108% |
| Full project (ADU + solar + barn) | $292,000 – $354,000 | $241k – $301k | **68% – 103%** |

Full-project midpoint is about **84% recovery** — roughly $0.84 of value for every $1.00 spent, with a finished dwelling for Tim at the end of it. Measured purely as an investment that is a modest loss; measured as family housing it is a good outcome. Both are true.

## Why these numbers are credible

- **Land rates:** the county values the first acre as a building site at **$95,000/acre** and the remaining 6.66 acres as residual at **$30,400/acre**. The residual carries a flood-fringe limitation.
- **New construction:** the house's replacement cost new is $476,159 over 2,685 sf — about **$177/sf**. That's the rate applied to the ADU.
- **Outbuildings:** utility buildings are valued at **$26.00/sf** base with a size adjustment, then depreciated by age — which is why the three existing outbuildings total only $8,714.
- **Validation:** the cost-approach total matched an actual arm's-length sale to within 0.3%. That's the strongest evidence here.

## Comparable sales — same market area, 2026

| Address | Size | Built | Sale date | Price |
|---|---|---|---|---|
| 737 Harold Dr | 1,552 sf | 1972 | 07/15/26 | $386,500 |
| 6014 Guess Rd | 1,610 sf | 1978 | 04/10/26 | $454,000 |
| 816 Running Cedar Trl | land only | — | 04/02/26 | $65,000 |
| 707 Donlee Dr | 1,796 sf | 1972 | 03/26/26 | $390,000 |
| 6119 Baird St | 1,404 sf | 1978 | 03/23/26 | $256,000 |
| **7105 Guess Rd (ours)** | **2,685 sf** | **1973** | **03/19/26** | **$630,000** |
| 6423 Whitt Rd | 1,314 sf | 1971 | 03/18/26 | $272,000 |
| 737 Harold Dr | 1,440 sf | 1972 | 03/13/26 | $185,000 |
| 7018 Windover Dr | 2,694 sf | 2007 | 03/11/26 | $548,000 |
| 123 Bywood Dr | 1,378 sf | 1966 | 02/10/26 | $355,500 |

These run $182–282/sf, but ours is the only one carrying 7½ acres — which is what separates it. Land rates, not per-square-foot, do the work.

## Open questions — what would move the numbers

**Five things to pin down before the number is locked:**

1. **Septic in scope?** The earlier contractor proposal bundled septic, sized for future needs. If it's outside the $215–260k, add real money and real time.
2. **The separate well.** The earlier scope tied into the existing well. A new well runs **$10,000–$25,000** and isn't in the number if it's separate.
3. **Solar is separate.** $35,000 fully out of pocket — the 30% federal residential credit expired December 31, 2025 (Section 25D), with no phase-down. Worth pricing owned vs leased, since third-party ownership is now the only route to any federal incentive.
4. **Garage finish level.** The $100–121/sf blended figure only holds if the 900 sf garage is shell or finish-light. Finished to living standard, that number moves up.
5. **County permit timelines.** Durham runs roughly 55–75 days. Worth building into the schedule.

**Two risks that aren't about cost:**

- **Assessment is not sale price.** The county will reassess upward after the build — expect roughly **+$1,140 to +$1,420/year** in county tax. But an assessment and a buyer's cheque are different things, especially for a property with few direct comps. Over-improving past what the local market will pay is the real risk.
- **Flood fringe.** The residual acreage carries a flood-fringe limitation, which constrains where structures can go. Relevant to barn siting.

## The option worth weighing: subdivide

RR zoning in the rural watershed tier requires a 3-acre minimum lot, and the parcel is 7.66 acres — so it can potentially split into two. If the ADU's site is platted as its **own 3-acre lot** with frontage and its own well/septic/electric, it stops being an accessory and becomes a **standalone rural Durham homesite**.

- County land value on a 3-acre split lot: ~$95,000 (building site) + 2 × $30,400 (residual) = **~$155,800** of land alone.
- Net gain versus keeping it as one parcel: **roughly $65,000** of additional land value.
- The bigger point: deeding the lot to Tim means he holds a **real, ownable asset** instead of an interest inside our property — cleaner for him and for the estate.

**Before designing anything:** twenty minutes with a real estate attorney on subdivision and deeding, and a call to Durham planning on the watershed buffer and setback requirements. Durham watershed districts can also require nitrogen-reducing septic — confirm before bidding.

## Bottom line

Spend roughly **$292,000–$354,000** across the ADU, barn, and later solar; the property goes from **$628,166 to about $869,000–$929,000**. That's a recovery of roughly **68–103%** — close enough to break-even that the deciding question isn't return, it's whether this is the right way to house Tim and get a working barn. On that question, the numbers say yes.

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### Sources & caveats

Prepared by Wren for Chris · October 3, 2026

Sources: Durham County Tax Administration parcel record (PIN 0816-57-1049, data current 10/02/2026); market-area improved sales R816C; CoCreations Construction & Design proposal (Aug 2026); NC pole barn cost data 2026.

All figures are working estimates for planning discussion, not quotes or appraisals. Value projections use the county's cost-approach model, which tracked a recent actual sale to within 0.3%. The full PDF version of this summary is attached to this page.