Why the two terms get confused
Most homeowners only ever do one or two building projects, so the language is unfamiliar. People say "I've got the plans done" and assume that covers everything a builder needs — but "plans" can mean very different things.
The confusion is understandable. Both sets are technical drawings, both are produced by a designer, and both can look similar at a glance. The difference is what each is designed to prove.
Planning drawings answer the question: "Is the council happy for this to be built here, looking like this?" Building-regulations drawings answer a different question: "How is this actually constructed so it's safe, warm and sound?" One is about permission and appearance; the other is about engineering and compliance.
Getting these mixed up is the single most common reason a builder's quote comes back vague, heavily caveated, or slow to arrive.
What planning drawings are for
Planning drawings exist to get a decision from your local authority — whether that's a full planning application or confirmation a project falls under permitted development.
They typically show the building in context: existing and proposed elevations, a site or location plan, floor layouts, and how the project relates to boundaries and neighbours. The emphasis is on scale, position, appearance and impact.
What planning drawings usually don't show is the technical build-up — foundation depths, insulation values, steel sizes, structural details. That's deliberate. The council assessing a planning application doesn't generally need to know the exact specification of a cavity wall; it needs to know the footprint, height and look.
What building-regulations drawings are for
Building-regulations drawings (often called "building-regs" or "technical" drawings) exist to demonstrate that the project meets the Building Regulations — the standards covering structure, fire safety, insulation, ventilation, drainage and more.
These are the working drawings a builder actually builds from. They tend to include construction details and notes: wall and floor build-ups, insulation specifications, structural elements such as beams and lintels, foundation information, damp-proofing, and how the new work ties into the existing structure.
Because they describe how the job is constructed, they're far more useful for pricing. A builder reading a good technical set can see the materials, the structural work and the standards being met, rather than guessing.
Why builder pricing needs technical detail
A quote is only as accurate as the information behind it. Ask three builders to price from a single elevation drawing and you'll often get three wildly different numbers — not because they disagree, but because each is filling the gaps with their own assumptions.
Technical detail removes guesswork. Foundation type changes cost. Steel sizes change cost. Insulation standards, drainage runs and how the build ties into the existing house all change cost. Without those details, a builder either pads the price to cover the unknowns or quotes low and revisits it later — neither helps you.
This is why a clear, complete set lets a builder produce a firm, comparable quote. Many trades now turn a measured set and site notes into a structured draft using quoting tools such as TailoredQuote; the builder still controls the scope, wording and prices, but the underlying detail is what makes the numbers meaningful. You can see how that drawings-to-quote workflow runs on our builder quote from drawings page.
Already had drawings prepared? We'll review the build scope and tell you what a builder still needs to price it properly.
Examples by project type
The mix of drawings you need varies with the project. Here's a rough guide for common Wirral and Liverpool jobs.
| Project | Planning drawings | Building-regs drawings |
|---|---|---|
| Single-storey rear extension | Often needed (or permitted-development check) | Needed to build and to price firmly |
| Two-storey or side extension | Usually needed | Needed — more structural detail involved |
| Loft conversion | May be permitted development; varies | Needed — structure, stairs, fire safety |
| Internal reconfiguration (no extension) | Often not needed | Needed where structural walls or beams are involved |
| Garage conversion | Often permitted development; varies | Needed — insulation, structure, ventilation |
This is a general illustration only — every property and street is different, and permitted-development rights can be restricted. Confirm what your specific project needs with a designer or your local authority before you commit. A design and drawing service such as SC Design Wirral may prepare both planning and building-regulations drawings for homeowners, alongside measured surveys and feasibility work, according to their public website at the time of writing.
| At a glance | Planning drawings | Building-regs drawings |
|---|---|---|
| Main purpose | Permission and appearance | Construction and compliance |
| Who it's for | Local planning authority | Builder + building control |
| Typical content | Elevations, site plan, layouts | Construction details, structure, specs |
| Good for a firm quote? | Ballpark only | Yes — the detail builders price from |
Which drawings might you have?
If you're not sure what's sitting in your inbox, this checklist helps you work it out before you send anything on.
Quick self-check
- Do the drawings show elevations and a site/location plan? You likely have planning drawings.
- Do they include construction notes, wall build-ups, insulation values or steel sizes? You likely have building-regs (technical) drawings.
- Is there a planning reference number or decision notice? That's the planning side, approved or in progress.
- Do you have both sets, clearly labelled? Ideal — a builder can quote far more accurately.
- Are you holding only a rough concept or visualiser image? That's inspiration, not a buildable or priceable drawing.
For more on what a complete extension set should contain, see our guide to extension drawings in Wirral. If you already hold drawings and want to know the next move, the SC Design Wirral resource hub covers common homeowner questions.
Before you send plans to a builder
A few quick questions save a lot of back-and-forth and help you get comparable quotes rather than guesses.
- Which sets do I actually have? Identify planning versus building-regs before sending, so the builder knows what they're working from.
- Are the building-regs (technical) drawings included? If not, expect a ballpark figure rather than a firm price, and ask the builder what they'd need to firm it up.
- Is the scope clear? Note what's included and excluded — finishes, kitchens, bathrooms and decoration are often outside the structural drawings.
- Are the drawings current? Make sure you're sending the latest revision, not an earlier draft that's since changed.
- Do I need a designer's input first? If you only have planning drawings, ask whether technical drawings are the sensible next step before quoting.
Send a builder a clear, complete package and you'll get a clearer, more honest quote back. Send half the picture and you'll usually get a heavily caveated one.
What this guide does not replace
This guide is general information to help you tell the two drawing types apart — it is not planning, legal or structural advice. Whether your specific project needs planning permission, falls under permitted development, or requires particular building-regulations detail depends on your property and must be confirmed with a suitable designer, planning professional or your local authority. WV Construction reviews build scope and provides quotes for CH and L postcode projects; it does not produce architectural drawings or grant approvals.How this fits WV Construction’s process
WV Construction works across Wirral and Liverpool (CH and L postcodes only) on extensions, renovations and general building works. When you get in touch, we review the drawings and build scope you already hold and tell you plainly what's needed to price the job firmly — rather than returning a vague number padded with assumptions.
If your project is a new room or larger reconfiguration, our residential extensions page explains how we work. Already have drawings? Use our already have drawings page to send them over for a scope review.
Common questions
Is planning permission the same as building regs?
No. Planning permission is about whether the council will allow the project, based on appearance, size and impact. Building regulations are separate standards covering how the project is safely built — structure, fire, insulation, drainage and more. A project can need one, the other, both, or in some cases neither.
Can a builder quote from planning drawings only?
A builder can give a ballpark from planning drawings, but it will usually carry caveats. Planning drawings show appearance and position, not construction detail, so the builder has to assume things like foundations, structure and insulation. For a firm, comparable quote, building-regulations (technical) drawings are normally needed. See our builder quote from drawings page.
Which comes first, planning or building regs?
Typically planning (or a permitted-development check) comes first, because there's little point detailing the construction of something that may not be approved. Building-regulations drawings usually follow once the overall design and any permission are settled — but the right order can vary, so check with your designer.
What is actually shown on building-regulations drawings?
They set out the technical build-up: foundations, wall and floor construction, insulation, structural members, drainage, ventilation and fire safety. This is the detail that lets a builder price and construct accurately, which appearance-only planning drawings don't provide. Confirm exactly what your project needs with a designer or your local authority.
Who produces building-regulations drawings?
An architectural design and drawing service or similar professional prepares them. SC Design Wirral, for example, is an independent design service that may prepare planning and building-regulations drawings for homeowners, according to their public website at the time of writing. WV Construction builds from drawings but does not produce them.
Written by WV Construction; details about TailoredQuote and SC Design Wirral reflect their public websites at the time of writing and may change.