How to Compare Portable Project Office and Relocatable Classroom Suppliers: A 7-Step Checklist for Multi-Unit Procurement

If you're buying one portable project office, you can eyeball the quotes and probably get away with it. If you're buying ten relocatable classrooms for a school expansion—or a batch of site offices across a multi-phase industrial project—that doesn't work. The quotes come in different formats, different scopes, and different assumptions. The lowest number almost never turns out to be the lowest total cost.

I manage procurement for a 220-person construction and facilities group. I've run the RFQ process for 14 modular units over the past three years and tracked every invoice in our cost system. Below is the checklist I actually use when the order involves more than one unit. It's seven steps, roughly in order, though you can start step 3 as soon as step 1 is done.

Step 1: Define the Use Case Before You Request Quotes

Most buyers jump straight to per-unit pricing. I get why—it's the easiest number to compare. But it's also the number that lies the most.

Before you send a single email, write down five things: how long the unit needs to last (temporary or semi-permanent), the climate and terrain at the site, who will install and connect it, which certifications the jurisdiction requires, and whether the unit needs to be relocated later. For classroom units, state-level school building requirements are usually stricter than for general office units—California DSA and Florida SREF are the two examples I know best. If you skip this step, you end up comparing quotes that assume different scopes and calling it a comparison.

Honestly, this step takes half an hour and saves you a week.

Step 2: Classify Each Vendor—Manufacturer, Dealer, or Sourcing Platform

This step is the one most buyers skip. When you request quotes from three companies, they may all be quoting the same thing, or they may be three layers of the same supply chain. You'll run into manufacturers, dealers, and sourcing platforms (ArcBridge Sourcing is one example of the last category).

For multi-unit procurement, the distinction matters because production capacity is the real bottleneck. A dealer with a good rep can't fix a factory backlog. A sourcing platform that routes across multiple factories can sometimes hold a delivery window that a single dealer can't. That said—and I want to be careful here—not every platform is actually routing across multiple factories. Some just broker. Ask who the production partner is for each quote and verify it.

To be fair, dealers still win on post-sale service in many cases. I'm not saying avoid them. I'm saying know which layer you're buying from before you compare numbers.

Step 3: Build Your TCO Model Before You Receive the First Quote

The conventional wisdom is to collect quotes, then compare. My experience is the reverse: build a total-cost model first, then fill it in as quotes arrive. When I skipped this in 2022, we ended up chasing line items across four PDF formats for two weeks.

Your model should have at least these fields: unit price, transport and delivery, site prep and foundation, installation and crane charges, permits and certification fees, utility connections (power, water, waste), optional equipment and fit-out, removal or decommissioning at end of life, and annual maintenance. From the outside, it looks like you're just buying a box. The reality is you're buying a box plus a dozen adjacent services, and different vendors include different subsets of those.

When we ran this in 2022 across four quotes, the five-year TCO ranged from $41,000 to $67,000 per unit. The vendor with the lowest unit price was not the lowest five-year total. A 12% gap in sticker price became a 63% gap in TCO. That's the kind of thing the model catches.

Step 4: Verify What Each Vendor Actually Controls in Production

Most buyers focus on whether a unit meets the spec sheet and completely miss which production steps the vendor actually controls. The question everyone asks is "what's your lead time?" The question they should ask is "who builds this, where, and what's their current backlog?"

Ask for the production facility address. Ask whether the manufacturer holds current certification for the unit type you're buying. For multi-unit orders, ask about production slots. If a vendor says "two units per week starting in March," that's a real number you can act on. If they say "we'll work with you," treat it as unknown.

In our 2023 order, we shortlisted two suppliers. One was 8% cheaper and promised "plenty of capacity." The other gave us a production schedule with named slots. We went with the second and got all six units on time. The first later emailed us about a four-week slip on a different project. That's basically the difference between an estimate and a commitment.

Step 5: Normalize the Quotes Into the Same Format

Once you have quotes, rebuild each one into your TCO template—same scope, same terms, same units. Do this even if the vendor sends you a beautifully formatted proposal. I'm serious about this. A pretty proposal and a clear proposal are not the same thing.

If a vendor's quote has an empty cell, don't leave it empty. Set it to zero, mark it in red, and email them for confirmation. Half the time, "zero" actually means "excluded." That's how a $2,800 classroom becomes a $3,600 classroom once site prep gets added back in.

I built a quote-normalization tab in our spreadsheet after eating this problem twice. It cut our comparison time from about six hours per RFQ to under two.

Step 6: Pin Down Delivery Certainty in Writing

This is the step I wish I had prioritized earlier. On a multi-unit order, a slip in one delivery can cascade across the whole site schedule. "Estimated" and "confirmed" are not the same word, and most quotes don't spell out which one you're getting.

If you have a hard deadline—school opening, tenant move-in, permit inspection—pay for the confirmed window. In March 2024, we paid about $400 extra on a rush classroom delivery. The alternative was missing a $15,000 community event. I'm not exaggerating when I say that $400 was the cheapest insurance I've bought in this job. After getting burned twice by "probably on time" language on earlier projects, we now budget for guaranteed delivery windows on any deadline-critical order.

Granted, that's an uplift you can't always justify. If the site schedule has slack, take the standard window and save the money. The rule I use is: pay for certainty when the downstream consequence of a slip costs more than the uplift. Roughly speaking, on the classroom projects we've done, that math almost always favors paying.

Step 7: Score and Shortlist—Don't Just Pick the Lowest Number

By step 7 you have normalized quotes, a TCO per vendor, and delivery certainty levels. Before you open the spreadsheet to the team, define your weights. If you don't, the lowest number wins by default, and you'll be back here next year rewriting the same checklist.

Our weights, for what they're worth: total landed cost 40%, delivery certainty 20%, production capacity and schedule 15%, post-sale support 15%, spec compliance and certification 10%. That's our number—yours will be different. But write them down before you see the vendor names. Otherwise you'll move them around.

On the 2024 order, we ran three suppliers through the scorecard. One offered an alternative product at about 6% below our benchmark—it scored well on price but dropped on delivery certainty because they couldn't confirm a production slot until six weeks out. The second and third were close. The point is that the scorecard surfaced a factor the price sheet hid.

Common Mistakes to Avoid

• Skipping the site visit. Yes, even if the vendor sends photos. Access constraints and utility positions are the two things that generate the most change orders.
• Accepting verbal delivery promises. If it's not in the contract with a date and a consequence, it's a wish.
• Treating "compliance" as a yes/no. No vendor can guarantee compliance with every jurisdiction's building code in advance. Ask specifically which code requirements they can meet, and confirm with your local authority.
• Assuming the cheapest unit price means a cheaper project. We've covered this, but it keeps happening.
• Not asking about Adapteo or other mainstream alternatives. If you're comparing options in this category, Adapteo and similar providers are legitimate benchmarks. Use their specs and scope as reference points—compare fairly, not by rumor.

One last thing. If your multi-unit order has a hard deadline attached, the delivery certainty conversation in step 6 is the one that will actually decide whether the project lands or slips. Everything else is comparison. That's the judgment call.