A price per square metre is a ratio, not a price. Two suppliers can quote almost the same rate for a 20 m by 40 m structure and still be 15 to 25 percent apart once the offers are built. The gap is rarely a negotiating trick. It comes from bay module, eave height, wall count and the long list of items that one supplier includes and another leaves to the buyer.

This article sets out a comparison method for buyers who already hold two or three marquee quotations and need a defensible decision, not another request for information.

A Rate Only Compares When the Bay Module Matches

Floor area is span multiplied by length. Frame quantity is not. A 20 m by 40 m structure covers 800 m² either way, but the number of bays changes with the module a supplier designs to.

At a 5 m bay, that length gives 8 bays. At a 3 m bay it gives 13.3 bays, which in practice becomes 14. The second structure carries more transverse frames, more legs, more roof sections, more membrane panels, more connections and more labour per square metre of floor. The rate should be higher. When it is not, something else in the offer has usually been trimmed.

Eave height moves the number in the same direction. Extra height adds leg length, more membrane area on walls and more wind exposure, and it changes how the structure is braced. A quote that states a 3 m eave is not comparable with one that states 4 m, even at the same span.

Before any money is discussed, confirm that both offers share the same span, length, bay module, eave height, ridge type and wall count. The marquee specification fields list is a practical checklist for that step, because each field changes either material quantity or engineering effort.

Build One Comparison Schedule Before You Read the Totals

The schedule is a single table with one row per scope item and one column per supplier. It takes an hour and removes most of the ambiguity from the decision.

Scope line	What the row must state	Why it changes the comparison
Structure	Span, length, bay module, eave height, roof profile	Sets frame, membrane and labour quantities
Frame	Series, profile size, alloy and temper	Different series are not interchangeable and cannot be extended together
Roof and walls	Membrane weight for roof and for walls, colour, translucency	Weight and coating drive cost and service life
Openings	Door type, size, quantity, position	Each opening is a framed item, not a cut in the fabric
Water management	Gutters, downpipes, outlet positions	Frequently excluded and expensive to add later
Anchoring	Method, base plate, ballast or foundation responsibility	Site-specific and often the largest hidden line
Installation	Labour, plant, supervision, who supplies tools	Decides whether the site price is real
Documents	Drawings, load basis, material and flame test reports	Needed for permits, insurance and internal sign-off
Spares	Recommended first-year spares, lead time	Separates purchase cost from operating cost

Any line marked as excluded, by others, or not stated is not free. It is unpriced risk that belongs to the buyer until somebody puts a number on it.

Where the Missing Scope Hides

The differences cluster in five places.

Walls and doors. Some offers price a roof only. Others include solid walls on three sides and a double door. The framing for a walled structure differs from an open structure, so this is not a simple add-on rate.

Gutters and downpipes. A structure without water management sends roof water to the perimeter, which is precisely where guests, equipment or stock tend to sit. Adding gutters after delivery means new parts and a second freight movement.

Anchoring. This is the line most often left open, because the supplier cannot size it without the site. A standard expansion bolt set suits some surfaces and not others. On a hangar project, the anchor specification moved to anchors rated at 30 kN on a concrete slab, an engineered solution rather than the standard event arrangement. That step change is a cost, and it belongs in the comparison rather than in a later variation order. The engineering detail behind that hangar structure shows how much of the scope sits outside the frame itself.

Installation and plant. A supply-only price looks lower until forklift hire, crew travel, accommodation and supervision are added. Structures with long spans or high eaves also need plant that a small local crew may not own.

Spares and compatibility. If the buyer operates a fleet, the value of a new order depends on whether its components match the existing stock. A cheaper frame from a different series can cost more over five years than a compatible one. Rental operators comparing offers should read how fleet selection differs from a one-off purchase before fixing the shortlist.

Convert the Gaps into Money

Take the cheapest headline offer. For every row it leaves blank, use the other suppliers’ line price where one exists, or a written add-on quote where it does not. Add those numbers to the headline. Repeat for each offer.

The discipline is refusing to compare totals until every column covers the same rows.

The worked example below uses illustrative figures, not any supplier’s pricing:

Line	Offer A	Offer B
Structure, 800 m², 5 m bays, 3 m eave	100,000	112,000
Solid walls, three sides	not included	included
Gutters and downpipes	not included	included
Door set, double leaf	2,400	included
Anchoring, grass, screw piles	3,600	included
Freight to port	2,800	2,600
Comparison total	108,800	114,600

Offer A is still lower here, but the margin collapsed from 12,000 to 5,800. Change one assumption, for example a concrete surface instead of grass, and the order can reverse. That is the point of normalising: it shows where the real difference sits.

Landed Cost Is the Number That Gets Approved

Purchase price and landed cost are different figures. Landed cost adds freight, insurance, duty, port charges, inland transport and the cost of clearing customs, and it depends on the delivery term each supplier quoted.

Under EXW the buyer arranges everything from the factory gate. Under FOB the supplier delivers to the named port and loads. CIF adds freight and insurance to the destination port. DAP and DDP move responsibility further, with DDP including import clearance and duty. A DDP offer will always look more expensive than an EXW offer for the same structure, because it contains more of the journey.

Two practical rules follow. First, ask every supplier to quote on the same term before comparing. Second, treat the duty basis as a separate question: classification and rates depend on the destination and the product, and a freight forwarder or customs broker should confirm them rather than a supplier’s estimate.

Score the Offers Instead of Ranking the Prices

Price ranking hides the trade-offs that matter six months after delivery. A weighted score makes them explicit. The weights below are a starting point, not a rule:

Criterion	Weight	Evidence to score it
Scope completeness	25	Number of unpriced rows remaining in the schedule
Technical fit	20	Span, bay module, eave height, frame series, membrane specification
Landed cost	25	Comparable total on one delivery term
Documentation	15	Drawings, load basis, test reports, packing list
After-sales	15	Spares availability, warranty wording, response route

Score each offer against the evidence, not the sales narrative. An offer that cannot produce a dimensioned drawing or a named load basis should lose points on documentation, regardless of price.

Read the Warranty Wording Before You Sign

Warranty is where comparable prices diverge most quietly. Check three things: what is covered, for how long, and from which date.

Frame, membrane and workmanship are usually treated separately, with different periods and different exclusions. The start date may be delivery, installation or first use, which matters when a structure is bought in advance of a project. Storm damage, improper anchoring and unauthorised modification are commonly excluded, and those exclusions connect directly back to the anchoring row in your schedule.

Ask for the warranty text with the quotation, not after the order.

What to Send Back Before Signature

Send the completed comparison schedule to the shortlisted supplier and ask for written confirmation of every row, including the ones already marked as included. This converts assumptions into a record and gives both sides the same baseline.

The marquee buying guide covers the earlier stage, where the brief, structure type and site conditions are still being defined. If the offers are already in hand, the remaining work is normalisation, landed cost and the risk lines above.

To price a specific configuration against your own comparison schedule, send the schedule with your project brief and include the application, destination, required span, bay module, eave height, wall and door requirements, surface conditions and delivery term.