Ever had three builders quote wildly different prices for 'the same' job? Usually it's because they weren't quoting the same job at all — each filled the gaps with their own assumptions. Clear drawings fix that. Here's what builders actually need to price your project properly.
In short
Builders can only price what they can see. Vague information produces wildly different quotes; a clear drawing pack lets several builders quote the same scope, so you can compare like with like — and the eventual build matches what you agreed.
Not sure which route applies to your property? Send Sean your name and one way to contact you for an honest first view — with no obligation. A postcode, a few photos and a short description help if you have them, but aren't required to start.
Reviewed by Sean Corser, SC Design Wirral. Sean Corser helps Wirral homeowners with architectural design and drawing packs for extensions, loft conversions, planning and building regulations.
Last reviewed June 2026
When the information is vague, every builder makes their own assumptions about specification, structure and finishes — and prices accordingly. One assumes a basic spec, another a premium one, and you're left comparing numbers that aren't comparable.
A clear set of drawings removes the guesswork, so the prices reflect the same work.
For an accurate quote, builders benefit from proposed plans and elevations, building-regulations drawings with construction details and specifications, and structural information where beams or openings are involved.
Together these define the scope: what's being built, how, and to what standard.
Drawings aren't just for quoting — they're the reference during the build. If a question comes up, the answer is on the drawings rather than decided on the spot, which keeps cost and quality under control.
It also makes the final result match what you agreed, not what someone assumed.
You don't need a full brief or drawings to get started — just your name and one way to contact you. The rest is optional, and you can send more whenever it suits you.
All you need to start is your name and one way to contact you. A short description, postcode or a few photos help if you have them — but they're not required.