If you've started getting prices for a loft conversion, extension, or refurbishment, you've probably received a range of numbers from different contractors — and wondered why they're so far apart. Part of the answer lies in something most homeowners don't realise: not all pricing documents are the same. A quote, an estimate, and a ballpark figure are three fundamentally different things. Confusing them is one of the most common and costly mistakes in residential construction.
Ballpark Figure: An Early Compass, Not a Destination
A ballpark figure is exactly what it sounds like — a broad, early-stage indication of cost based on limited information. It's used at the beginning of a project to help you understand whether your idea is broadly feasible within a budget range, before you've committed to architectural drawings, surveys, or detailed scoping.
A ballpark is useful. It helps you make early go/no-go decisions. But it is not a reliable basis for budgeting a real project. It's produced without detailed drawings, without site inspection, without specification, and without real-time supplier input. The assumptions built into a ballpark can change significantly once proper information is available.
A responsible contractor will always make the basis and limitations of a ballpark figure explicit. If someone gives you a ballpark and presents it as a reliable price, that's a warning sign, not a reassurance.
Estimate: A Structured, Informed Projection
An estimate is produced once meaningful information is available — typically after a site visit, after architectural drawings have been reviewed, and after the scope of works has been discussed in reasonable detail.
An estimate is not a fixed price. It is an informed projection based on the information available at the time. It will include assumptions — about finishes, about provisional quantities, about what the client will supply — and those assumptions should be made explicit in the document.
A good estimate is a structured commercial document. It should tell you what's included, what's excluded, what the assumptions are, and what would need to happen to convert it into a firmer price. It gives you something real to work with and plan around, while being honest about what could still change.
Quote: A Fixed Commitment Against a Defined Scope
A formal quotation is a fixed price against a clearly defined scope of works. To produce one properly, the contractor needs complete information: finalised drawings, a confirmed specification, known quantities, and ideally real-time supplier pricing. A quote says: "if the scope is exactly this, the price is exactly this."
The problem is that many contractors issue "quotes" that are actually rough estimates dressed up in quote language — fixed-looking numbers produced without the information needed to fix them. When scope questions arise on site — which they always do — those numbers quickly unravel.
Why Cheap Quotes Often Cost More
The most seductive thing about a low number is that it looks like a saving. But a low number produced without proper scope discipline isn't a saving — it's a debt. The missing costs don't disappear. They come back as variations: additional charges raised once work has started and it's difficult to change contractor.
Common things that get missed in under-scoped pricing:
- Structural engineer fees and steel supply
- Building Control application and inspection fees
- Drainage diversions or build-over considerations
- Temporary support and propping during structural alterations
- Provisional sums that aren't adequately flagged
- Second-fix items that are assumed but not stated
- Contingency for unknown conditions (particularly in older London properties)
When you're comparing prices, the question isn't just "which is lowest?" It's "which document tells me the most about what's actually included?"
RCB's Pre-Construction Process: Better Information, Better Pricing
At RCB Design & Build, we don't produce ballpark figures and call them quotes. Our pricing process is tied to our pre-construction process: we gather the right information before we commit to numbers, and we're explicit about what we know, what we're assuming, and what would change the figure.
Where drawings and technical information are complete, we produce detailed, stage-by-stage pricing with clear exclusions and assumptions documented. Where projects are at an earlier stage, we'll provide a structured ballpark with a clear explanation of its basis and limitations.
We also ask the questions that many contractors skip — about drainage constraints, party wall obligations, structural complexity, and client-supplied items — because the answers affect the price, and our clients deserve to know that before they commit.
Better pre-construction discipline doesn't just produce better pricing. It produces fewer surprises, fewer variations, and a smoother project.
Want pricing you can actually trust? Contact RCB Design & Build for a structured pre-construction conversation about your project.
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