A drawing set is the record that everyone on a project relies on. Architects use it to check the design, contractors use it to price and build, and inspectors use it to verify what was installed. When drawings are unclear, out of date or inconsistent, the consequences show up on site as delays, rework and disputes.
This guide explains what CAD drawing and computer-aided drafting services include, the difference between drafting and engineering design, the drawing types and standards you are likely to need, and how to evaluate a drafting company before you commission one.
What CAD Drafting Services Include
CAD drawing services produce technical drawings from information that already exists. That information may be a survey, a marked-up PDF, a hand sketch, an earlier drawing set, a design report or a set of engineering decisions made by the project team. The drafter converts this into a clear, dimensioned and standards-compliant drawing set.
Typical services include drawing creation from sketches, conversion of PDFs to CAD, preparation of layouts and details, updating existing drawings, producing schedules and drawing registers, and preparing as-built records.
Drafting, Design Engineering and Engineering Approval
Three different activities are often grouped together, and it is worth separating them:
| Activity | Who carries it out | What it produces |
|---|---|---|
| Engineering design | Qualified design engineer | Design basis, calculations, system decisions, specifications |
| CAD drafting | Drafter or CAD designer, under instruction | Drawings and schedules recording the design |
| Engineering approval | Engineer of record and the relevant authority | Sign-off that the design meets applicable requirements |
A drafting provider can help you present a design clearly, but the design responsibility and approval stay with the appointed engineer. Make sure your scope says which party makes each decision.
Types of Drawings and Documentation
- Plans: floor plans, reflected ceiling plans and roof plans showing positions and routes.
- Sections and elevations: vertical views showing heights, levels and relationships between services.
- Details: enlarged views of connections, fixings, mounting heights and typical arrangements.
- Schematics and riser diagrams: system-level views showing how equipment and cabling connect.
- Schedules: door, equipment, cable and room schedules that accompany the drawings.
- Drawing registers and transmittals: records of sheets issued and to whom.
Revision Control and Drawing Registers
Every issued sheet should carry a revision identifier, a date, a status (for example, for information, for approval or for construction) and a description of the change. A drawing register lists all sheets in the set with their current revision. Revision control prevents superseded drawings from being used on site.
Good practice is to issue a transmittal with each set, recording which sheets changed. This allows recipients to replace only the affected sheets and to check that they hold the correct version.
Layer Management and Drawing Organisation
Layers organise information by type, such as walls, doors, services, annotation and dimensions. Consistent layer naming makes drawings easier to read, edit, filter and plot. Most projects follow a recognised convention, or define one in the drawing standard. Avoid placing content on layer zero, avoid unnecessary exploded blocks, and keep external references clean and documented.
Standards such as ISO 13567 describe layer organisation for technical product documentation, and many national and client standards adapt these principles for building drawings. Confirm which standard applies to your project before drafting starts.
Coordination With Architectural and MEP Drawings
Services drawings depend on the architectural and structural base. If the base changes, the services drawings must be checked. A practical approach is to:
- Agree the base file and its revision before drafting starts.
- Set common levels, grids and coordinate references.
- Overlay services on the base and check clearances at key points.
- Record the base revision used in each services sheet.
- Review clashes at coordination meetings and log the decisions.
Quality Checks and Drawing Reviews
A drawing review should check more than appearance. Useful checks include:
- Dimensions and levels against the source information
- Scale, north point, title block and revision data
- Symbols and legends matching the notes and schedules
- Cross-references between sheets and to details
- Schedules matching quantities shown on the plans
- The drawing register matching the sheets in the set
Common Drafting Mistakes and How to Avoid Them
- Outdated base drawings: confirm the base revision at the start and at each update.
- Inconsistent scales: set scale conventions in the template and check plotting settings.
- Missing or conflicting dimensions: query the source rather than estimating values.
- Schedule mismatches: reconcile schedules with the plan after every revision.
- Unclear notes: write notes in plain, specific language, and avoid copying notes from unrelated projects.
How to Evaluate CAD Drafting Companies
When comparing companies, ask for:
- Examples of drawing sets in your discipline, with personal details removed
- Their drawing standard, template and checking process
- Their revision and transmittal process
- Software versions and file formats supported
- A clear statement of which design decisions they make, and which they do not
For a wider selection process, see How to Choose a CAD Design Company.
How ASDV Consultant Supports Drawing Packages
ASDV Consultant prepares CAD drafting and documentation for ELV, ICT and building services projects, including layouts and schedules prepared to a defined drawing standard. Our engineering design services sit alongside the drafting support, so the design basis and the drawings stay consistent. You can read more about our structured cabling design and fire detection and alarm design services, or contact us with your drawing requirements.