Commercial Mortgages vs Buy to Let Mortgages vs Bridging Finance

Landlords often ask whether they should use a buy to let mortgage, a commercial mortgage, or bridging finance. The right answer depends on the asset, the timing, and the plan for repayment. This guide explains the core differences so you can choose the most effective route for your circumstances.

1) What Each Product Is

• Buy to let mortgage: Term lending for a single residential investment property. Underwriting centres on the property’s rent and loan to value, with set criteria and standard documentation.
• Commercial mortgage: Term lending assessed on the landlord’s wider business. Used for portfolios, HMOs, multi unit freehold blocks, mixed use, semi commercial, or cases outside standard criteria.
• Bridging finance: Short term funding that is fast to arrange. Used to purchase quickly, release equity, resolve refurbishment works, or bridge to a refinance or sale.

2) When Each Is Most Suitable

• Buy to let: Vanilla single lets, straightforward leases, strong rental cover, and where the cheapest pricing over a longer term is the priority.
• Commercial mortgage: Portfolio refinance, complex property types, corporate structures, short leases, or when borrower income and assets are central to the case.
• Bridging: Speed critical purchases, auction timelines, uninhabitable properties, light or heavy refurbishment, or when you need to complete before a term lender will accept the asset.

3) How Lenders Underwrite

• Buy to let: Primarily interest cover ratio and maximum loan to value. Personal income is secondary unless top slicing applies.
• Commercial mortgage: Portfolio income and expenses, borrower track record, business accounts, liquidity buffers, and covenants. Greater flexibility if the overall story is strong.
• Bridging: Asset value today and the credibility of the exit. The exit is usually a refinance or a sale. Evidence for the exit is critical.

4) Pricing, Terms, and Security

• Buy to let: Typically the lowest rates, two to five year fixes are common. Fees and early repayment charges apply.
• Commercial mortgage: Rates higher than buy to let but can be keen for strong borrowers. Options for interest only or amortising. Covenants may apply.
• Bridging: Short terms, often six to twelve months. Interest can be serviced or retained. Fast completion offsets higher cost, provided the exit is certain.

5) Risks and Mitigations

• Buy to let: Stress testing can cap the loan amount. Mitigate with realistic rents, accurate costs, and considering a product that allows top slicing if appropriate.
• Commercial mortgage: Potential covenants and personal guarantees. Mitigate by planning liquidity, negotiating sensible covenants, and documenting your risk controls.
• Bridging: Exit risk and cost escalation. Mitigate by evidencing the exit with an agreement in principle or agent comparables, and building contingency into timelines and budgets.

6) Typical Use Cases

• Buy to let: Stable single lets where long term cost matters most.
• Commercial mortgage: Refinancing ten properties into one facility to improve cash flow and governance.
• Bridging: Buying a property that is not lettable yet, completing works, then refinancing onto a term product.

7) Documentation Checklist

• Buy to let: Tenancy agreement, proof of rent, valuation, personal ID, source of funds.
• Commercial mortgage: Full portfolio schedule, business accounts and tax returns, assets and liabilities, rent roll, leases, management information, business plan.
• Bridging: Purchase contract or title, schedule of works, builder quotes, evidence of end value, refinance agreement in principle or sales agent letter, exit timeline.

8) How to Decide

Start with your objective and your timing. If you want lowest long term cost on a simple unit, buy to let is usually right. If you need flexibility for a portfolio or a complex asset, consider a commercial mortgage. If speed or works are the blocker, bridging can unlock the deal, provided the exit is reliable and evidenced.

The Role of an NACFB Broker

NACFB member brokers help you match the product to the plan, present the application professionally, and manage lender expectations. This reduces the risk of decline, delays, and unnecessary cost.

Conclusion and Takeaway

Each product solves a different problem. Define the goal, evidence the numbers, and plan the exit before you apply. With expert packaging, lenders can take a balanced view and support the outcome you need.

Next Steps

If you would like to discuss your own circumstances with an NACFB member broker, please complete the short form below and a consultant will be in touch.

Published: 17 September 2025