If you are asking what drawings for building control are needed, you are usually at the point where ideas need to become something buildable. That is where many projects either start moving properly or start running into delays. Building control is not interested in rough sketches or sales-style visuals. It needs technical drawings that clearly show how the work will comply with the Building Regulations.
For homeowners, that often comes as a surprise. A floor plan that looks neat and easy to read is not automatically enough for approval. A builder may understand your intentions from a simple drawing, but building control needs detail – dimensions, construction build-ups, structural information, insulation performance, drainage arrangements and far more besides. Every line matters because every line can affect compliance, cost and site progress.
What drawings for building control usually include
The exact package depends on the project, but most building control submissions need more than a basic existing and proposed floor plan. In most cases, the drawings need to explain the work in a way that leaves very little open to guesswork.
For a house extension, loft conversion, garage conversion or new build, the core drawing set often includes existing and proposed plans, elevations and sections. Those drawings should show the layout, sizes, heights, openings, foundations, roof form and relationship to the existing property. The key point is that they must do more than illustrate the design. They need to demonstrate compliance.
That usually means the package also needs construction details. These are the drawings and notes that show how walls, floors, roofs and openings will actually be built. Building control officers want to see the thermal elements, damp protection, ventilation strategy, fire safety measures and structural approach. If drainage is affected, drainage layouts and inspection chamber details may also be needed.
On many projects, structural calculations sit alongside the drawings rather than replacing them. A steel beam design from an engineer is important, but on its own it does not explain the whole build. The drawings still need to show where those elements go and how they connect with the rest of the construction.
What building control wants to see on the drawings
A good way to think about it is this: building control needs enough information to assess whether the work can be built legally and safely. If drawings are vague, the application may be delayed, queried or approved with conditions that push decisions down the line.
Plans
Floor plans should show room uses, dimensions, wall thicknesses, door and window positions, drainage runs where relevant, and any key compliance points such as escape windows, protected stair routes or accessible WC layouts. On an extension, they should also make clear what is new and what remains.
Elevations
Elevations are not just for appearance. They can help show finished ground levels, external materials, window positions, roof heights and relationships to boundaries. That matters when the build-up of the wall, cavity and roof structure affects compliance.
Sections
Sections are often where a building control package becomes properly useful. A section cuts through the building and shows how the parts come together vertically. It can identify ceiling heights, roof insulation, floor construction, foundation depth assumptions and the way an extension ties into the existing house.
Construction details
These are the drawings that answer the practical questions. What is the roof build-up? How is the floor insulated? What cavity closers are being used around openings? How is a flat roof ventilated or designed as warm roof construction? Where is the damp proof course in relation to external levels? These details reduce the risk of site confusion later.
Why planning drawings are not always enough
This is one of the most common points of confusion. Planning drawings and building regulations drawings may overlap, but they are not the same thing.
Planning drawings are mainly about the principle and appearance of development. They show what is being proposed, how it looks and how it sits on the site. That level of information may be enough for the planning department, but building control works to a different test. It needs to know how the project will perform in practice.
That is why a planning-approved scheme can still need a more developed technical drawing package before work starts. If you only submit the original planning drawings to building control, you may find they lack the detail needed for approval. That is especially common on extensions, conversions and renovation projects where existing structures introduce more variables.
The level of detail depends on the project
There is no single answer that covers every job. A small internal alteration will not need the same package as a new-build house. Equally, a straightforward rear extension may need fewer specialist details than a loft conversion with complex steelwork, fire protection upgrades and stair changes.
For example, a garage conversion often requires detailed information on floor insulation, wall treatment, ventilation, fire separation and window compliance. A loft conversion usually needs even more attention to stairs, head height, structural strengthening, means of escape and thermal upgrades. New builds require a much broader drawing and specification package because every element must be assessed from the ground up.
This is where experience matters. The right drawing package is not about producing paperwork for the sake of it. It is about providing the level of information that fits the project and avoids unnecessary back-and-forth.
Full Plans versus Building Notice
When people ask what drawings for building control are needed, the answer can also depend on the route being used.
Under a Full Plans application, detailed drawings are submitted before work starts so that the design can be checked in advance. This is generally the safer route for most substantial domestic work because it gives clearer direction before builders are on site. It can reduce uncertainty and helps pricing become more accurate.
A Building Notice route involves less upfront detail at submission stage, but that does not mean detailed information will never be needed. In practice, building control can still ask for drawings, structural details and specifications as the work progresses. For anything more than very simple work, relying on minimal information can create pressure on site and leave too much open to interpretation.
For homeowners and small developers trying to control cost and programme, that trade-off matters. Less paperwork at the start can sound attractive, but it may lead to more risk during construction.
What happens when the drawings are too basic
Poor drawing packages tend to create the same problems again and again. Builders price without full information, then discover extra work later. Building control raises queries once work has started. Insulation thicknesses, drainage routes or structural bearings are left unresolved until site conditions force a decision. None of that helps budgets or timescales.
Basic drawings can also shift too much responsibility onto the builder to work things out as they go. Some builders are highly capable, but they should still be building from clear technical information rather than filling gaps in the design. That is how misunderstandings happen, especially where different trades need to coordinate.
Detailed plans that get approved do more than satisfy the local authority. They make the build smoother because the contractor, engineer and inspector are all working from the same information.
Common drawing elements people overlook
A surprising number of applications stall because of small omissions rather than major design faults. Thermal details are a frequent issue, particularly around roof build-ups, floor upgrades and junctions with existing walls. Ventilation information is another, especially in kitchens, bathrooms and converted spaces.
Drainage can also be underestimated. If a new extension affects existing inspection chambers or foul and surface water runs, that must usually be shown properly. On structural work, padstones, beam bearings and load paths need to be thought through, not added as an afterthought.
Fire safety details often become critical in loft conversions and larger alterations. Escape windows, fire doors, protected routes and smoke alarm layouts may all need to be clearly addressed on the drawings.
Getting the drawings right before work starts
The best time to solve technical issues is before materials are ordered and before trades arrive on site. That sounds obvious, yet many projects still move forward on partial information because everyone is keen to get started.
A properly prepared building regulations package gives you a clearer basis for quotations, a more reliable route through approvals and fewer surprises once work begins. It also gives your builder something practical to build from rather than a set of intentions that still need decoding.
For clients across Lancashire and the wider GB market, this is often where professional design support proves its value. A family-run practice such as JC Building Design Ltd can bridge the gap between concept, approval and construction by producing drawings that are not just presentable, but technically useful.
If you are planning work and wondering what to prepare, the safest approach is simple: do not ask whether the drawings look good enough. Ask whether they show enough to build legally, clearly and with confidence. That is usually the difference between a project that flows and one that keeps stopping for answers.