Five units is a real dividing line. At four units and below a property is residential and can be financed with residential products including DSCR. At five and above it is commercial multifamily, underwritten on net operating income, and a different set of lenders applies. The 5-to-20 unit band sits in an awkward middle — too large for residential lending, too small for most institutional multifamily capital.
In short: A multifamily purchase loan for a 5 to 20 unit property is commercial financing underwritten on the building’s net operating income rather than the borrower’s personal income. Crossing the five-unit threshold moves a property out of residential lending entirely. This size band is often called the small-balance gap because it falls below the minimum most institutional multifamily lenders will write, which is precisely why placing across multiple capital sources matters more here than at larger sizes.
At four units a property is residential. DSCR loans apply, gross rent drives the ratio, and the lender pool is wide. At five units it becomes commercial multifamily: underwriting shifts to net operating income after normalized expenses, third-party reports become more involved, and the lender pool narrows. Investors moving up from small residential rentals are frequently surprised by how different the process feels for a building only one unit larger.
Most institutional multifamily lenders have loan minimums that a 5 to 20 unit building rarely clears. Meanwhile residential lenders stop at four units. That leaves a genuine gap served by regional banks, credit unions, debt funds and specialty lenders — a fragmented field where terms vary widely and no single source is consistently best. It is the clearest argument in investment lending for shopping a deal rather than accepting one quote.
Commercial multifamily value derives from net operating income and the market cap rate. Lenders do not accept a seller’s expense figures at face value; they normalize for management, maintenance, reserves and vacancy at market rates even when the seller self-manages and reports lower costs. That normalization routinely reduces NOI below the offering memorandum number, which reduces value, which reduces the loan. Underwrite it yourself before the offer.
Many 5-to-20 unit deals are value-add: below-market rents, deferred maintenance, or partial vacancy. A property in that condition often will not support permanent financing at the price being paid, because current NOI does not carry the debt. The common structure is bridge to acquire and stabilize, then refinance into permanent multifamily financing once the rent roll supports it. The permanent takeout should be underwritten before the bridge closes.
Experience with multifamily specifically, not just with rentals generally. A borrower with eight single-family rentals is not automatically credible on a sixteen-unit building, because the operating discipline differs. Capital sources vary a great deal in how much they weight this and whether a third-party property manager can offset limited experience — another reason the same deal receives meaningfully different answers from different sources.
Four units and below is residential property, financeable with residential products including DSCR loans underwritten on gross rent. Five units and above is commercial multifamily, underwritten on net operating income after normalized expenses, with a different and narrower set of lenders.
Some capital sources offer DSCR-style products for small multifamily above four units, which is one of the more useful edge-case programs in the market. Availability varies considerably by source and by state, so it is worth asking rather than assuming the property has to go the commercial route.
The range where a loan is too large for residential lending and too small for most institutional multifamily lenders. Buildings in the 5 to 20 unit band frequently fall into it. The gap is served by regional banks, debt funds and specialty lenders whose terms vary widely.
Gross rental income less normalized operating expenses — management, maintenance, insurance, taxes, utilities and reserves — at market rates rather than at the seller’s actual costs. A self-managing seller reporting no management expense will still see a management line imposed in underwriting.
Yes, though usually not with permanent financing at the outset. The common path is bridge financing to acquire and stabilize, then a refinance into permanent once occupancy and rents support the debt service. That exit should be underwritten in principle before the bridge closes.
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