The True Cost of Development Finance: Fees, Interest and Contingency

Development finance costs are the total price of borrowing to build, made up of the interest rate plus a stack of fees, professional costs and contingency that rarely appear in a headline quote. For Hillingdon developers appraising a property development scheme, the development finance rate is only the starting point: the true cost of property development finance is the sum of every charge from arrangement to exit, and the single most expensive line is usually the one nobody budgets for, running out of money before practical completion. We arrange development finance across the borough, and this guide sets out what a facility actually costs, how development finance rates work, and how to compare quotes properly.

What property development finance actually costs

Development finance is specialist, short-term commercial funding for property development, and it is priced very differently from residential mortgages or standard commercial mortgages. A senior development loan usually covers 55 to 65 percent of gross development value (GDV), and lenders release the money in staged drawdowns against an independent quantity surveyor's valuations as the property development work progresses. The development finance rate a lender quotes is only one of six or seven separate costs. The full list of development finance costs on a typical property scheme is: the arrangement fee, the interest, the exit fee, the valuation and monitoring surveyor fees, legal fees on both sides, the broker fee, and, on undrawn facilities, a non-utilisation fee. Add the contingency you should carry and the equity you must contribute, and the headline development finance rate becomes a small part of the true cost.

Because development finance is unregulated commercial lending in most cases, the Financial Conduct Authority does not cap these fees, so they vary widely between lenders. That is precisely why the true cost of a property development loan is only visible once every line is added into a single blended figure. Two development finance facilities quoted at the same rate can cost tens of thousands of pounds apart once the fees and the drawdown profile are taken into account. Whether you are funding a residential development or a commercial scheme, the discipline is the same: reduce every quote to one number before you commit.

How development finance rates work in 2026

Development finance rates are quoted as an annual interest rate on the loan, and in the current market senior development finance rates start from around 6.5 percent per annum for strong schemes with experienced developers. Stretch senior facilities, which lend to a higher loan to cost, sit from about 8 percent, and mezzanine finance rates start from around 12 percent per annum. These development finance rates are not the whole story: the rate you actually pay depends on your track record, the loan to GDV, the property type, and how the lender prices risk on your specific development.

Property development finance interest rates also move with the wider cost of money, so the current rate environment matters. When base rates are higher, development finance interest rates rise with them, and the interest becomes a larger share of total development costs. This is why comparing today's development finance deals on rate alone is misleading. A lender offering a low headline rate but high fees, or an exit fee charged on GDV, can be the more expensive development finance deal once every cost is counted. The best development finance deals are bought on total cost, not on the advertised interest rate, and they usually go to developers who can secure keen terms by presenting a strong scheme.

How much can you borrow, and what factors affect your costs

How much you can borrow drives most of your development finance costs, because the loan sizes off two numbers: gross development value and total cost. Senior lenders will typically advance up to 60 to 65 percent of GDV, or around 70 percent of cost, on a first charge over the property. The factors that decide where in that range you land, and therefore what you pay, are your development experience, the quality of the scheme, the exit route, and how much cash you can put in. The more equity you contribute, the lower the loan to value, and the keener the development finance rates a lender will offer.

Several additional factors feed into the cost of borrowing. Lenders assess planning status, build cost certainty, and whether your exit is a sale or a refinance onto buy-to-let or commercial mortgages. A scheme with planning in place, a fixed-price build contract and a clear exit will secure better development finance deals than one where those factors are still open. When you apply, the more of this you can evidence, the lower the risk premium in your rate, and the lower your total development finance costs. This is the practical work involved in getting a keenly priced facility, and it is where a broker earns the fee.

How interest really accrues on a development loan

The most misunderstood of all development finance costs is the interest. On residential mortgages you pay interest on the full balance from day one. On a development loan, interest is charged only on the funds you have actually drawn, and it is usually retained, or rolled up, rather than serviced monthly. That means no monthly payments during construction, but it also means the interest compounds within the facility and is repaid in full at exit.

Because lenders release the loan in tranches as the build progresses, your average drawn balance over the term is far lower than the total facility. A developer who is granted a 2 million pound development loan does not pay interest on 2 million pounds for the whole term. On a 15 month property development scheme, the sort of timeline common on Hillingdon sites, the average outstanding balance might be nearer 55 to 60 percent of the facility, so the effective interest cost is materially below a naive rate multiplied by loan multiplied by term calculation. When you compare development finance rates and quotes, model the interest on the drawdown schedule, not on the headline loan amount, or you will overstate the cost and reject the cheaper facility.

The property development finance fees beyond the rate

Every development finance facility carries fees that sit outside the interest rate, and they add up quickly:

On a property scheme borrowing around 2 million pounds, these development finance fees commonly total 4 to 6 percent of the loan before a single pound of interest is counted. Any honest comparison of development finance costs has to bring all of them into one number.

Contingency: why running out of money is the most expensive outcome

The most expensive thing that can happen on a development is not a high development finance rate. It is running out of money before practical completion. When a scheme overruns on cost or programme and the facility is fully drawn, the developer faces the worst set of prices in the entire property finance market. Default interest rates on development finance are commonly 2 to 3 percent per month, several times the standard rate. On top of that come standstill costs, extension fees, further legal and valuation charges, and, in the worst case, a forced sale of a half-finished building that no ordinary buyer wants.

This is why contingency is not optional padding but a core part of the cost of building. A prudent development appraisal carries a contingency of at least 5 percent of build cost on a new build residential development and 10 percent or more on a refurbishment or conversion, where hidden problems are common. Under-sizing the contingency to make an appraisal look better is the classic way developers turn a profitable property scheme into a distressed one. When we assess a Hillingdon development, we would rather see a realistic contingency and a slightly lower day one loan than an optimistic budget that leaves no room for the delays that a 15 month programme almost always produces.

Comparing the cost of debt with giving up profit share

Once senior debt is in place, most property schemes still have a funding gap between what the senior lender advances and the total cost of the development. That gap is filled either with more debt, usually mezzanine finance secured by a second charge, or with equity from a partner. Each has a very different cost.

Mezzanine finance is priced from around 12 percent per annum and sits behind the senior development loan, governed by an intercreditor agreement that sets out who is repaid first. It is expensive money, but it is finite: you pay the coupon and the fees, and when the property sells, the mezzanine lender takes no share of the upside. Equity is the opposite. A joint venture equity partner may fund the whole gap, and sometimes the deposit too, without charging monthly interest or requiring a personal guarantee, but in return they take a share of the profit, often 40 to 50 percent. On a development that performs well, that profit share can cost far more than any interest bill. On a scheme that underperforms, equity is cheaper, because the partner shares the loss rather than sitting as a fixed debt on top of a shrinking margin. Deciding between them means comparing debt and equity costs across the capital stack rather than looking at headline development finance rates alone.

A worked total cost example

Take a modest Hillingdon property development. Local values average around 420 pounds per square foot (HM Land Registry Price Paid Data 2025), so a small residential block delivering 6,000 square feet of saleable space has a GDV of roughly 2.5 million pounds. Assume total development costs, including land, build and fees, of about 2 million pounds. A senior lender advances 60 percent of GDV, roughly 1.5 million pounds, from a development finance rate of 6.5 percent per annum, over a 15 month term.

The interest, modelled on an average drawn balance of about 55 percent of the facility rather than the full amount, comes to somewhere near 70,000 to 80,000 pounds. Add an arrangement fee of around 22,000 pounds, an exit fee of a similar order, monitoring and valuation fees, and legal costs on both sides, and the total cost of the senior development finance lands close to 150,000 pounds across the project. The remaining 500,000 pound gap must be covered by mezzanine finance, which adds its own coupon and fees, or by an equity partner taking a profit share. Only when you set that full debt cost against the profit you would surrender to an equity partner can you see which route is genuinely cheaper for your property development.

How to compare development finance deals properly

Because lenders quote in different ways, the only fair comparison is total cost to exit expressed as a single figure. When we place a Hillingdon property development scheme, we reduce every development finance deal to the same basis:

A development finance deal with a slightly higher rate but lower fees and a loan-based exit fee often beats a headline-cheap quote once the full cost is built up. Property development finance is a market where the best deals go to developers who apply with a complete, well-presented appraisal, because that is what lets a lender price risk keenly. You can model your own scheme with our development finance calculator, and if you want us to reduce live quotes to a like for like total cost, contact our team with your appraisal.

Frequently asked questions

Can you get 100 percent development finance?

Not from senior debt alone, which is capped at 55 to 65 percent of GDV. You can reach effectively 100 percent of costs by adding mezzanine finance or a joint venture equity partner on top of the senior development loan, though each adds its own cost, whether a coupon or a share of profit.

What are the development finance rates in 2026?

Senior development finance rates currently start from around 6.5 percent per annum for strong schemes, with stretch senior from about 8 percent and mezzanine finance from around 12 percent. The development finance rate you are offered depends on your experience, the loan to GDV, and the strength of the property development.

How much deposit do I need for development finance?

As a rule, expect to contribute the difference between the senior loan and total cost, commonly 35 to 45 percent of costs, unless you top up with mezzanine finance or equity. First time developers often use a JV equity partner to cover the deposit shortfall so they can apply for a development loan they could not fund alone.

What actually makes one development finance deal more expensive than another?

Rarely the interest rate alone. The biggest differences are whether the exit fee is charged on loan or on GDV, the size of the arrangement fee, and how the facility is drawn, since interest accrues only on the amount lenders release. Always compare total development finance costs to exit, not the headline rate.

Data sources: HM Land Registry Price Paid Data 2025; local planning authority data 2025. Development finance rates and figures are indicative, vary by scheme and lender, and are subject to change. Development finance is typically unregulated commercial lending.

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