The DWG lands in your inbox at ten past four on a Thursday. Eleven megabytes, called something like SURVEY_ISSUE_rev3_FINAL(2).dwg, from a surveying company you've never spoken to. You open it and everything is on layer 0, in a colour scheme that appears to have been chosen by a fruit machine, and the director says "can you get existing, demolition and proposed out for planning by Wednesday."
Right. Here's the sequence, and it's the same sequence every time. Interrogate the survey before you trust it. Go to site and check the six things the surveyor never records. Clean the line work and rebuild the layers. Save that as a base file you never touch again. Chain three drawings off it by save-as — existing, enablement, proposed — so that every one of them is a direct descendant of measured fact rather than a redraw. Build the elevations out of the same base. Then number the set so an officer can find their way round it. Do it in that order and the Wednesday deadline is fine. Do it out of order and you'll be redrawing at midnight on Tuesday.
A measured survey is somebody else's opinion about a building, recorded on a day you weren't there. Some of it is laser-accurate. Some of it is a tape measure held by a bloke who couldn't get behind the fridge.
Before anything else, run three checks.
Units. Draw a temporary line across a door opening and measure it. If it tells you 826, the file is in millimetres and you're fine. If it tells you 0.826, it's in metres and every hatch pattern, text height and line type you bring in from your template will be a thousand times the wrong size. Fix it now with a scale factor about the origin, not after you've drawn three floors.
Origin and rotation. Check where the file sits relative to 0,0 and whether it's on true north or site north. If the survey is a million units from the origin because it's been set out on OS coordinates, decide right now whether you keep that or move it, because every xref in the project inherits that decision.
Closure. Walls that look continuous at 1:100 often aren't. Zoom to a corner at full scale and you'll find lines overshooting by 40mm, duplicate lines stacked on each other, and polylines that were never polylines. This is the stuff that silently ruins hatching later.
Then look for what isn't there at all. Surveyors give you what they were asked for. What's routinely missing: ceiling heights room by room (not just one section), finished floor levels between adjoining rooms, the direction and size of floor joists, the position of the meter cupboard and the incoming services, gutter and ridge heights on the elevations, and anything in a locked cupboard. None of that is the surveyor's failing. It just isn't in the brief you inherited.
Six Things to Check on Site Before You Draw a Single Line
Go to the building. An hour there saves a week later, and this is the part a Part 1 gets told to skip because it isn't billable. Take the survey printed at A3, a tape, a laser and a pen.
Storey heights and level changes. Step up into the back addition? Measure it. A 150mm level change nobody drew is the difference between a workable scheme and a ramp.
Which walls are doing something. Tap them. Solid masonry, timber stud, blockwork, a chimney breast boxed in with plasterboard. You're not making a structural judgement, you're recording what you found so the engineer can.
Soil stacks and drainage. In our experience this is the single biggest killer of an otherwise lovely refurbishment plan — the boxed-in cast iron stack in the corner of the store cupboard that lands exactly where your proposed en-suite wants to be. Photograph it, measure it off two walls.
Windows: cill height, head height, opening type. Elevations live or die on this.
What the building is made of, externally. Brick bond, render, cill and lintel details, roof covering. You'll need it for the elevation annotation and the planning officer will notice if you get it wrong.
Ground levels around the building. Especially if there's any fall across the site. A topographical survey covers it; a building survey often doesn't.
Mark up the print. Photograph every room from two corners. That mark-up becomes the evidence trail for every deviation you make from the surveyor's file.
Clean It, Then Lock It
Now the tedious bit, which is also the bit that determines whether the rest of the job is pleasant.
At Studio RBA we always insist on a proper measured survey in CAD from a surveying company rather than sending staff out with a tape — and then we clean it, every time, because surveyors draw literally and architects draw representationally. The clearest example is windows. A survey typically shows the wall line running straight past the opening with the frame drawn in thin lines somewhere inside it. What we do is delete the heavy external wall line across the opening and replace it with a thin line representing the cill, then extend the frame to meet the reveal properly. Same information, but now the window reads as a window at 1:100 instead of a smudge.
While you're in there: purge, audit, overkill, delete the surveyor's title block and their text styles, explode nothing you don't have to, and rebuild the layers into your office standard. Walls, windows, doors, floor finishes, levels, annotation, fixtures, structure-above dashed. Line weight by layer. If your practice hasn't got a standard, borrow one and be consistent — a survey cleaned into a coherent layer structure can be switched on and off to make a dozen different drawings later, and one that isn't will be redrawn for each.
When it looks right, save it as the existing-condition base and stop editing it. That file is your fact. Everything else in the project is a copy of it.
Three Files, One Lineage
Here's the convention most UK practices use, ours included, and it's worth understanding why rather than just copying it.
Existing is what's there. No aspiration, no wishful thinking, no "the client says the wall's coming out anyway."
Enablement — also called demolition, or strip-out — is a save-as of existing, with everything to be removed identified on its own layers in a thick red dashed line type. This is a real drawing with a real audience: the contractor's first job on site is stripping the building back, and this is the drawing they work to.
Proposed is built on top of the enablement drawing, xrefed in underneath. Not a copy of the existing with bits rubbed out. Referenced, so that when you spot another wall that needs to go — and you will, three weeks in — you change it once in the enablement file and the proposed drawing updates with it.
That's the lineage: measured survey → cleaned base → existing → enablement → proposed, each one a descendant of the last. Nothing in the proposed set is drawn from memory. Every line traces back to something someone measured.
Red Dashed, and the Key That Makes It Mean Something
A red line with no key is a decoration. The key is the drawing.
At minimum your enablement key must distinguish four states, and they must be visually different at A3 when printed in black and white by someone in a planning office:
Existing to be retained — thin, black or greyed back.
Existing to be removed — thick red dashed.
New work — usually blue on the enablement drawing if you show it at all, and solid black with hatching on the proposed.
Existing openings to be formed or infilled — these get missed constantly, and they are precisely what a structural engineer needs to price.
There is no national standard forcing red-for-demolition on you. It's convention, near-universal and perfectly understood — but the validation requirements sit with the local planning authority, so check the checklist of the one you're submitting to before you assume.
Two notes we put on every enablement drawing as a matter of studio habit. First, if you aren't certain what's load-bearing — and on a conversion you usually aren't — write it down: structure indicated is assumed; engineer to review and confirm prior to any removal. You're not hedging, you're allocating the question to the person qualified to answer it. Second, for anything built before 2000, a note that a refurbishment and demolition asbestos survey is to be carried out before strip-out begins. HSE guidance treats pre-2000 buildings as potential asbestos risks; the survey itself is the duty holder's responsibility, not yours, but putting the note on the drawing means nobody can say they weren't told.
Show services too — the stack, the gas meter, the position of the consumer unit. A contractor reading a demolition plan with no services on it will find them the hard way.
Elevations Are Built, Not Redrawn
The survey already contains your elevations in raw form: measured heights, opening positions, roof lines. The job is to project the plan information into them consistently, not to draw a new picture of the building.
Set up existing elevations first, from the base. Then — exactly as with the plans — copy the whole lot, model and sheet, to make the proposed set. On a conversion where the external treatment barely changes, the difference between existing and proposed elevation might be a handful of items, and that's fine. What matters is that the two drawings are demonstrably the same building.
Which brings up a trick worth stealing. On a pub-to-hotel conversion we did, the existing elevation carries the old pub signage and the proposed carries the new hotel sign — so anyone flicking between the two sheets can tell at a glance which is which without squinting at the title block. Small thing. Saves a planning officer three seconds a hundred times.
Then annotate the proposed elevation with a numbered key against the things you're actively telling the planners: all previous signage removed. Satellite dish and external lighting removed. Existing crest retained and made good. Removals matter as much as additions on a planning elevation. What you're retaining matters most of all on anything with heritage value.
Number It So Somebody Else Can Read It
Whatever system your office uses, keep the three-way split legible in the numbers themselves. Ours runs existing in one number block, enablement in the next, proposed in the next — so 1000-series existing plans, 1100-series existing elevations, 2000-series enablement, 3000-series proposed plans, 3100-series proposed elevations. An officer looking for the proposed rear elevation shouldn't have to open five PDFs.
Every sheet gets a scale bar, north point, the drawing status, and a revision. Issue as separate PDFs named the way the planning portal wants them, not as one merged document called Drawings.pdf.
Why the Discipline Pays
Six weeks after submission the case officer asks for the rear extension to drop 400mm and the side window to move. If your proposed drawings are an independent redraw, you now edit plans, elevations, section and demolition plan separately and pray they still agree. If they're a referenced descendant of a locked survey base, you change the enablement file and the proposal above it, and the rest follows.
That's the whole argument for the lineage. Not neatness. Not office standards for their own sake. It's that a refurbishment project changes constantly, and the only drawings that survive change are the ones that were never lying about where they came from.
A new-build plan forgives you. You draw a wall and the wall is exactly where you drew it. An existing building doesn't forgive anything — it was built by people who are dead, altered by people who didn't tell anyone, and measured by someone who couldn't reach behind the fridge. Your job isn't to draw it beautifully. It's to build a set of drawings that can absorb the truth when it turns up late.
