Case Study: T-Mobile Wants to Triple Your Rooftop Cell Site — Should You Let Them?

A client of ours recently came to us with a problem that’s becoming increasingly common in California. T-Mobile wanted to expand their rooftop cell site from a single-sector sled-mounted installation to a full three-sector macrocell — five additional antennas, structural steel, roof penetrations, two crane permits, the works. Why isn’t the site already three sectors?  Difficult zoning.

The complication? Our client is planning to sell the building this year.

T-Mobile offered a couple of hundred dollars more per month in rent for the expansion. On the surface, that sounds like free money. But when we dug into the construction drawings and our client asked intelligent questions about the expansion’s implications, the picture got a lot more complicated. We thought this was a great case study of the issues building owners don’t always think through when a carrier asks to “modify” an existing site.

What T-Mobile Was Actually Proposing

Let’s be clear about the scale of what was on the table. This wasn’t a simple equipment swap. T-Mobile wanted to convert a compact, single-pole sled installation into a three-sector site with antennas pointed in multiple directions, mounted to the roof with structural steel. The construction drawings called for opening the rooftop, installing a beam, and pulling two crane permits.

When we reviewed the drawings, the footprint of the new installation dwarfed the existing one. This is the kind of detail that gets lost when a carrier’s project manager describes the work as a “modification” or “upgrade.” The word “upgrade” implies a minor improvement. What T-Mobile proposed was closer to a new build atop the existing lease.

The Arguments for Letting Them Proceed

We always try to give our clients a balanced view, so let’s start with the upside.

Reduced termination risk. A carrier that just invested heavily in expanding a site isn’t walking away from it. If T-Mobile needs three-sector capacity at this location, rejecting the request could prompt them to find an alternative nearby rooftop — one where the landlord says yes. Approving the expansion effectively locks in the revenue. The existing lease rate is already fair.

Increased property value — in theory. More lease revenue should mean a higher property valuation. At the right rent, the additional cash flow could be marketed as an asset when the building goes on sale. Alternatively, our client could sell the lease income stream separately — typically at around 18 times the annual rent — and pocket that independently of the building sale.

The Arguments Against — And This Is Where It Gets Real

Here’s what concerned us, and what ultimately shaped our advice.

Roof access becomes a serious operational problem. Three-sector antennas pointed in different compass directions create RF exclusion zones — hatched-out areas on the construction drawings where no one can safely work while the antennas are live. In our client’s case, the antennas were positioned near the center of the roof. That means any significant roof work — HVAC maintenance, re-roofing, waterproofing — would require coordinating a power-down with T-Mobile. While T-Mobile typically responds quickly, it still means the building owner has more to deal with on their roof.

For a building owner about to go to market, that’s a real issue. A prospective buyer is going to ask about roof access, and “you’ll need to coordinate with T-Mobile every time” is not the answer they want to hear. And the expansion means that the new owner would be prevented from using the roof for a balcony or roof deck.

Roof penetrations mean leak risk — and carriers don’t make that easy. The existing sled-mounted setup sat on the roof without penetrations. The new construction drawings showed permanent mounts requiring structural attachment to the roof. Every penetration is a potential leak point.

We tell every client the same thing: getting a carrier to take responsibility for a roof leak is one of the most frustrating experiences in this industry. They will blame the membrane, the age of the roof, the flashing, the weather — anything but their installation. They defer to their contractor to address the issue and that contractor may not even be in the area. If you don’t have an active roof warranty, you need an independent inspector to review the work. If you do have a warranty, the carrier’s contractor must coordinate with your roofing vendor before a single bolt goes in, or you risk voiding it.

Temporary relocation goes from easy to expensive. Right now, the sled can be physically moved if the building owner needs the roof area. A permanently mounted three-sector site directly mounted to the rooftop? That’s a temporary relocation project that could cost tens of thousands of dollars — and unless your lease specifically addresses it, the carrier will expect you to pay.

The visual impact is significant. A single-pole sled is discreet. A full three-sector macrocell is comparatively huge. We pointed out to our client a specific page in the construction drawings that showed the relative scale, and the difference was striking. While most buyers won’t care, some will — and in competitive California real estate markets, giving any subset of buyers a reason to pass is a risk worth weighing.

New lease terms almost always favor the carrier. A modification of this scale may include an amendment that allows the carrier to slide in more favorable language — larger exclusive-use areas on the roof, new restrictions on what the building owner can do near the equipment, ROFRs, and term extensions. Those restrictions transfer to the buyer, and they could impact the new owner’s plans for the property. For a building that’s about to be listed, adding encumbrances to the lease is a serious consideration.

What We Told Our Client

Given the near-term sale timeline, we laid out three options:

Reject the modification outright. Let the new owner decide whether to approve the expansion. This keeps the building clean and simple for the sale, with no new encumbrances. T-Mobile isn’t going anywhere in the short term — they need the existing site, and they’ll make the same request to the new owner.

Make an aggressive counteroffer. If the expansion is worth doing, it’s worth doing at the right price. A few hundred dollars a month for a project of this scale is low. We suggested a much larger amount as a starting point, with strong protections around roof access, penetration repair obligations, and relocation costs. If T-Mobile accepts, the building goes to market with a stronger income story.

Defer to timing. The real question was how soon the building would be listed and how long it would take to sell. If the sale was months away, approving a major roof construction project during the marketing period creates complications — noise, cranes, construction activity — that no seller wants.

The Takeaway for Building Owners

This case is a good reminder that not every carrier “upgrade” is good for the landowner. The word “modification” covers everything from a simple equipment swap to what amounts to a brand-new installation, and the implications for your property vary enormously.

Before you approve a major expansion, get the construction drawings and actually study them. Understand the physical scale of what’s being proposed. Look at where the antennas are positioned and what that means for roof access. Ask whether there will be penetrations. And don’t accept the first rent increase the carrier offers — it’s almost always a starting point, not a final number.

If you’re planning to sell, think carefully about whether a larger, more complex cell site will help or hurt your marketability. There’s no universal answer, but it’s a question that deserves more than five minutes of thought — no matter how eager the carrier’s project manager is to get your signature.

And if you need help reviewing the plans and thinking practically about the request and what it is truly worth, reach out to us for a free initial discussion.