Quick answer (updated October 2026): Send existing and proposed floor plans, elevations and any sections or specification you have, ideally as PDFs drawn to a metric scale of 1:50 or 1:100. The more detailed the drawings, the more accurate the estimate: outline drawings support a budget estimate, while building regulation drawings give the most accurate figure.
On this page
The Essentials
For most projects, we need:
- existing and proposed floor plans;
- elevation drawings;
- sections, if you have them;
- any project specification or notes on materials and finishes.
PDF is the preferred format, but we also accept DWG and image files. Drawings should be to a metric scale, ideally 1:50 or 1:100, so we can measure from them accurately. Email them to mail@first4estimating.com.
How the Drawing Stage Affects Accuracy
The detail in your drawings sets how precise the estimate can be.
| Drawings you have | Estimate | Typical accuracy | Starting price |
|---|---|---|---|
| Outline or sketch drawings | Budget estimate | Within 15–20% | From £75 + VAT |
| Planning drawings | Planning drawing estimate | Within 10–15% | From £95 + VAT |
| Building regulation drawings | Building regulation estimate | Within 5–10% | From £150 + VAT |
Building regulation drawings add structural details, construction methods, insulation, drainage layouts and material schedules, which is why estimates from them are the most accurate.
What Else Helps
- Structural engineer’s drawings and calculations, so steelwork and foundations can be priced properly.
- A specification or a list of the finishes you have in mind (for example, mid-range or high-spec kitchen and bathrooms).
- Site information such as access restrictions, ground conditions or known drainage runs.
- Your postcode, so we can apply regional labour and material rates.
- Photographs of the existing building, particularly for refurbishment and remedial work.
What If I Only Have Sketches?
You can still get a useful figure. If you only have sketches or preliminary drawings, we can provide an indicative estimate or a feasibility study — just get in touch and we’ll advise on the best approach. We note any assumptions we’ve had to make, so you can see what the figure depends on, and we can update the estimate when fuller drawings are ready.
Tip: Many clients get a budget estimate at the sketch stage, then a building regulation estimate before choosing a builder. Commissioning an estimate early can also support planning and funding applications.
Drawings by Type of Project
- Extensions: existing and proposed floor plans and elevations, plus a section through the new structure if available. Note any steelwork or structural openings into the existing house.
- Loft conversions: existing and proposed floor plans, a section showing the new roof and floor build-up, and details of the staircase position.
- New builds: a site plan, floor plans for every level, elevations, sections and any foundation design or ground investigation.
- Refurbishments and conversions: existing and proposed plans, a written scope or schedule of the work, and photographs of the existing building.
- Commercial projects: the full drawing set and specification, plus any mechanical and electrical information. For tenders, send the architect’s complete tender pack.
Common Gaps That Slow Things Down
The most common problems we see are drawings without a scale or dimensions, plans that don’t match the elevations, missing structural information, and no indication of the specification level. None of these stop us estimating, but each one means an assumption. We’ll flag anything missing when we quote, so you can decide whether to send more information or proceed on stated assumptions.
If you’re working with an architect or designer, ask them to send the latest revision of every drawing together, as a single set of PDFs. It’s the quickest way to an accurate estimate.
What Happens Next
Once we receive your drawings, we review them and send a fixed-price quotation for the estimating work, raising any questions upfront. Standard estimates are delivered within 5 working days as a PDF report and editable Excel file. See how it works for the full process, or send your drawings now.