Updated August 16, 2026
You do not need one to sell, but your buyer's lender will almost certainly order one, so it is going to happen either way. A Phase I Environmental Site Assessment is a records-and-inspection review — historical land use, regulatory databases, aerial photographs, a site walk, and interviews — designed to identify recognized environmental conditions. It does not involve sampling. Most agency and bank lenders require one on a multifamily acquisition, and in Los Angeles the recurring findings are predictable: former dry cleaners, gas stations, and auto repair on or adjacent to the site, historic oil production, and underground storage tanks. Whether a seller should commission their own depends on whether the site has a history worth getting ahead of.
Historical land use. City directories, Sanborn fire insurance maps, aerial photography, and title records going back decades. In Los Angeles this is where the surprises come from — a parcel that has been apartments since 1961 may have been something else in 1948.
Regulatory database review. State and federal records of known contamination, leaking underground storage tanks, and cleanup sites, on the property and within a search radius around it.
A site reconnaissance. A walk of the property looking for staining, drums, transformers, floor drains, vent pipes, and other physical indicators.
Interviews and a report. With owners, occupants, and local officials where available, concluding either that no recognized environmental conditions were identified or that specific conditions warrant further investigation.
Adjacent dry cleaners. The single most common finding on urban LA multifamily. Perchloroethylene from decades of dry cleaning operations migrates, and a dry cleaner two doors down in 1975 shows up in 2026.
Former service stations and auto repair. Underground storage tanks, whether removed with documentation or not. An undocumented tank removal is worse than a documented one.
Historic oil production. Large parts of Los Angeles sit over former and active oil fields. Idle and abandoned wells appear on parcels across the basin, and methane zones affect development and sometimes financing.
Methane and methane buffer zones. A City of Los Angeles designation that carries specific requirements, most consequentially for redevelopment.
Prior industrial use. Common in submarkets that were industrial before they were residential.
Usually not, on a straightforward building. The buyer's lender will order theirs regardless, and it will be the report that governs their decision. Paying for a report that is then duplicated is money spent twice.
Yes, if the site has a history you already know about. A former gas station on the corner, an old tank, a neighbor with a documented release. Knowing what the report will say before a buyer does lets you frame it, price it, and gather the closure documentation. Surprises in week three of escrow are what cause retrades.
Yes, if you are selling to a developer at land value. Environmental condition is far more consequential for redevelopment than for continued apartment operation, and a clean report meaningfully strengthens the position.
Yes, if a prior report exists. Find it. A ten-year-old Phase I with a documented closure letter is valuable evidence and answers questions before they are asked.
A recognized environmental condition does not usually kill an apartment deal — it changes the sequence.
Phase II. Actual sampling of soil, soil vapor, or groundwater to determine whether contamination is present and at what concentration. Weeks, not days, and it extends escrow.
Regulatory closure documentation. Frequently the issue is historical and already closed by the oversight agency. Producing the closure letter resolves it.
Environmental insurance or an indemnity. Used where a condition exists but is quantifiable and manageable.
Price adjustment or a holdback. Where remediation is genuinely needed.
Lender refusal. The outcome that actually ends deals. Some lenders will not fund on an unresolved recognized environmental condition, which means the buyer needs a different lender or all cash.
Assume a Phase I will be done on your building and think about what it will find before you list. If you know the parcel's history is clean and unremarkable, let the buyer's lender order it and move on. If there is a dry cleaner, a service station, an oil well, or an old tank anywhere in the story, get ahead of it — find any prior reports, locate closure documentation, and consider ordering your own so the conversation happens on your timeline rather than in the middle of escrow.
How much does a Phase I cost and how long does it take?
It is a modest expense relative to a multifamily transaction and typically takes a couple of weeks. A Phase II, if one is triggered, costs substantially more and takes considerably longer — which is why the timeline risk matters more than the report cost.
Does a clean Phase I protect me from later claims?
It documents the condition of the property as assessed at that time and supports the buyer's own due diligence position. It is not a warranty from the seller, and it does not substitute for accurate disclosure of what you actually know about the property.
Is a Phase I required for a 1031 exchange?
No. It is a lender and buyer diligence item, not an exchange requirement. But if a Phase II or a remediation question delays your closing, that does affect exchange deadlines — which do not extend for environmental review.
Michael Sterman is Senior Managing Director Investments at Marcus & Millichap.
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