A data center construction loan is not sized off the building. It is sized off how much of the building is already spoken for, and by whom. That single fact explains most of the distance between two quotes on the same site.
The backdrop
CBRE put North America primary-market vacancy at 1.6% and reported that 74.3% of capacity under construction was already preleased, against a historical norm closer to 40 to 50 percent, and expects preleasing to hold in the mid-70s through 2026 (CBRE · North America Data Center Trends · H2 2025). For a construction lender, both numbers say the same thing. Demand risk, the thing development lending usually exists to price, has largely left this asset class.
It has not disappeared. It has moved to power and to schedule.
What a signed lease does to the credit
A preleased megawatt changes what the lender is underwriting. With an executed lease to an investment-grade occupier, the loan looks closer to a corporate credit exposure wrapped in a construction risk period than to a speculative real estate loan. Norton Rose Fulbright's project finance practice described lenders financing contracted cash flows from hyperscale tenants rated AA or AA+, with private credit pricing at roughly 100 to 150 basis points over the same tenant's corporate bonds (Norton Rose Fulbright · Data Center Financing Structures · 2025-06-11). When the pricing reference is a tenant's bond curve rather than a real estate spread, the lender has stopped underwriting the building.
Uncontracted capacity gets the opposite treatment. Without a lease the lender is taking absorption risk in a market where requirements are quoted in megawatts and negotiated years ahead of delivery. That shows up in structure more than in any single number: lower proceeds against cost, sponsor recourse that burns off only at defined stabilization tests, an interest reserve funded past the delivery date rather than to it, and cash management from the first draw.
Most real projects are neither. A campus with two of six halls leased is priced on the leased share and structured around the rest, which is why proceeds on partially preleased projects vary so much between lenders.
The two questions preleasing does not answer
The first is power. A lease commits the developer to a delivery date, and the utility, not the general contractor, usually controls whether that date is achievable. Where new transmission or generation is required, CBRE reports interconnection timelines running 24 to 48 months and beyond (CBRE · 2026 US Real Estate Market Outlook). A signed lease with a delivery date the grid cannot support is a liability. That is why an executed utility will-serve letter or a signed interconnection agreement now sits ahead of zoning in a lender's diligence file, and why energization dates get tested against the utility's own study documents instead of the sponsor's schedule.
The second is cost and schedule certainty. Preleasing fixes the revenue side and does nothing for a budget exposed to switchgear, transformer, and generator lead times that have run long since 2023. Lenders answer that with a fixed-price, date-certain construction contract carrying liquidated damages, an independent engineer signing off on every draw, and a contingency line they size themselves.
Why the structure looks the way it does
Bank paper on development here is usually a mini-perm: construction funding plus three or four operating years, then a refinancing (Norton Rose Fulbright, above). The takeout is the capital markets. Roughly $25 billion of data center securitization priced in 2025, split close to evenly between ABS and CMBS where the historical split favored ABS at about 70/30 (RBC Capital Markets · December 2025), and outstanding securitized data center debt grew from about $4 billion in 2020 to $61 billion by mid-2026 on Barclays figures (Barclays via Structured Finance Association · Research Corner · 2026-07-23).
The construction facility is therefore a bridge to a market that only opens once leases are executed, in place, and seasoned. Preleasing sets proceeds at the front end and decides whether the exit exists at the back end. A sponsor optimizing purely for construction leverage can arrive at the balloon holding an asset the takeout market will not price.
What to have ready before going to lenders
The boundary worth naming
A data center financing can be underwritten two ways. Real estate credit sizes on cost, value, and coverage against contracted rent. Project finance credit sizes on cash flow available for debt service inside a project company, with sculpted amortization, funded reserve accounts, and direct agreements with the tenant and the contractor. Powered shell on a long lease usually prices as the first. A large campus funded at the project company level with a full contract stack is the second, and that is a different lender set, different documents, and a longer timetable. Working out which one a project belongs in before the process starts is worth more than an extra turn of leverage.