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Start here · The flagship guide

The STR Deal Underwriting Manual

How to underwrite a short-term rental end to end — set honest assumptions, estimate revenue without fooling yourself, model the real cost stack, and reach a go / no-go you can defend.

New to Builders Finance? Start here. This guide introduces the whole Deal Analysis system, and links to every supporting guide you'll need as you put it in place.

Reading time16 min
Edition2026.1
AuthorMatt Nunn
Living reference — kept current as rules, tools, and operating practices change.
What it covers
  • The five-step underwriting sequence
  • How to discount an AirDNA projection
  • The costs owners always forget
  • When the honest answer is no
Read the Underwriting Manual →

Start with the flagship above — everything else in Deal Analysis supports it.

Supporting guides

The guides, in order

In dependency order — Assume before you calculate — every model inherits its assumptions.

01
Assumptions

The Assumptions Behind Every Model

Every model is only as good as its inputs. Set them conservatively and pressure-test them.

02
Revenue

Estimating STR Revenue Without Fooling Yourself

ADR, occupancy, RevPAN — and how not to overestimate.

03
Costs

What STRs Actually Cost to Run

The full operating-cost stack, and why your Airbnb isn't cash flowing.

04
Returns

How STR Returns Are Measured

Cash-on-cash, cap rate, break-even — and which to trust.

05
Verdict

Does This Deal Actually Pencil?

The capstone decision, with the calculator attached.

Browse all Deal Analysis guides chronologically →
Decision guides

When there's a real choice

Judgment calls, not how-tos — each weighs the options for your situation.

Decision Guide

Does This Deal Actually Pencil?

The go/no-go — revenue, costs, financing, and reserves in one verdict, with the calculator.

Work through it →
Decision Guide

Should I Buy in This Market?

Demand, seasonality, saturation, and regulatory risk — before the property model.

Work through it →
Templates & tools

The tools that do the most

The guide teaches; the tool implements.

Tool

The Honest STR Underwriting Calculator

Conservative / Expected / Optimistic ranges, not a single flattering number.

Pairs · Does This Deal Pencil?
Tool

Break-Even Occupancy Calculator

The occupancy floor a property must clear to cover its costs.

Pairs · Break-Even
The Informed Operator

Stay ahead of the changes.

A weekly email on the financial side of short-term rentals — what changed, why it matters, and what owners should understand. Plus the STR Tax Mistake Checklist.

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