Summary

Most plasterers who struggle with margin aren't undercharging on the trowel work — they're failing to separate labour cost, material cost, and profit into distinct numbers before they quote. A single blended "£25/m²" rate hides all three, and when a job runs long because the walls needed more bonding coat than expected, there's no way to see which part of the price absorbed the overrun. This guide sets out the pricing components separately so a plasterer building a quote — not a customer trying to benchmark a price — can see where the money actually sits.

The core structure is: cost (what the job genuinely costs you to run — materials plus your own labour time valued at what you need to earn) plus margin (the buffer that covers quoting risk, non-chargeable time, and profit) equals price (what goes on the quote). Skipping the middle step and jumping straight from "day rate" to "price" is how experienced plasterers still end up working for less than they think, because day rate alone doesn't account for materials, waste, or the small jobs that don't fit neatly into a day.

For customer-facing benchmark prices by room and surface type, see skim coat pricing guide — that article answers "what should this cost me" from the customer's side. This article answers the same numbers from the other direction: "what does this cost me to deliver, and what margin am I actually running."

Key Facts

Quick Reference Table — Cost Build-Up Per m² by Job Type

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Job type Material cost/m² Labour time/m² (mins) Labour cost/m² (at £33/hr) Cost subtotal/m² Price at 30% margin
New plasterboard skim, 2-coat, good access £3.50 12–17 min £6.60–£9.35 £10.10–£12.85 £13–£17/m²
Existing sound plaster, PVA prep + skim £4.50 17–24 min £9.35–£13.20 £13.85–£17.70 £18–£23/m²
Uneven wall, bonding coat + skim £7.50 30–40 min £16.50–£22 £24–£29.50 £31–£38/m²
Lath-and-plaster, sound, skim over £5.00 30–36 min £16.50–£19.80 £21.50–£24.80 £28–£32/m²
Overboard + skim (lath loose) £9.00 42–50 min £23.10–£27.50 £32.10–£36.50 £42–£47/m²
Strip to studs, board, scrim, skim £11.00 55–66 min £30.25–£36.30 £41.25–£47.30 £54–£61/m²

These figures build up from labour time and material cost separately, then apply margin on top — compare against skim coat pricing guide to sanity-check where your build-up lands against typical market pricing.

Detailed Guidance

Step 1 — Separate labour cost from your day rate

Your day rate isn't your labour cost per hour by default — it's your price, which already contains a margin decision you made when you set it. To build an accurate quote, work backwards:

  1. Take your day rate (e.g. £250/day)
  2. Divide by realistic productive hours (typically 7–7.5, not 8 — allow for setup, breaks, and clean-down within the day)
  3. That gives a raw hourly figure (£250 ÷ 7.5 = £33.30/hour) — this is your time cost, not your margin-inclusive price

Use this hourly figure to price time on a job, then add margin afterwards as a separate step (see Step 3), rather than mentally blending "time plus profit" into one number while you're estimating.

Step 2 — Price materials at cost, then mark up separately

List every material a job needs and price it at what you actually pay (trade account price, not RRP):

Total this as a genuine cost figure, then apply your material margin (20–35%) on top as a separate line, even if you don't show it separately on the customer-facing quote. This is the number that tells you whether a job is actually profitable — blending materials into a flat per-m² rate hides material cost inflation (plaster prices move) until your margin has silently eroded.

Step 3 — Apply margin as a deliberate decision, not a leftover

Once you have cost (labour time × hourly rate, plus materials at cost), decide your margin percentage deliberately:

Margin is not profit you "hope" to make after costs come in under budget — it should be built into the number before the job starts, and protected by accurate condition assessment at quote stage (see Step 4).

Step 4 — Inspect before quoting, every time

The single biggest driver of margin erosion in plastering is quoting a per-m² rate without seeing the wall condition. A wall with two old chase repairs and a patched section behind a removed radiator might be 40% bonding-coat work and 60% straight skim — if quoted at the "straight skim" labour time, the overrun comes directly out of margin, then out of your own hourly rate, then — if the job runs long enough — out of the material cost buffer too.

Before pricing:

Step 5 — Handle small jobs and half-days correctly

A single 8m² ceiling priced at your per-m² rate for a full room job will almost always undercharge, because setup and clean-down (45–90 minutes) is the same whether the job is 8m² or 40m². For small jobs:

Worked example — full quote build-up

Job: Standard 4×4m bedroom, walls and ceiling, existing sound plaster in reasonable condition (PVA prep, no bonding coat needed). Total area 45m².

Step Calculation Result
Labour time 45m² × 20 min/m² (existing plaster, mid-range) 900 min = 15 hours
Labour cost 15 hrs × £33.30/hr £499.50
Material cost 45m² × £4.50/m² £202.50
Total cost £499.50 + £202.50 £702.00
Margin at 30% £702.00 × 0.30 £210.60
Quoted price £702.00 + £210.60 £912.60, round to £900–£950

Cross-check against skim coat pricing guide's market range for this room type (£950–£1,600 for a standard bedroom skim over existing plaster) — a build-up landing at the low end of the market range signals either a tight margin worth revisiting, or a genuinely efficient operation; a build-up landing above the market range signals the estimate needs re-checking before it goes to the customer.

Frequently Asked Questions

Should I quote per m² or build up from labour and materials every time?

For repeat job types you know well (standard bedroom skim, plasterboard-only), a per-m² rate calibrated from your own cost build-up is faster to quote and perfectly reliable — the point of this guide is to make sure that per-m² rate is actually derived from real cost data, and re-checked periodically as material prices and your own day rate change, rather than copied from a rate card years out of date.

How often should I recalculate my per-m² rates?

At minimum, whenever plaster/material prices move meaningfully (check every 6 months) or when you change your day rate. A rate built up two years ago on old material prices and an old day rate is quietly eroding your margin every time you use it without re-checking.

What margin should I be running as a minimum to stay viable?

Most trade pricing guidance treats 20–25% as a bare minimum that barely covers business overhead (insurance, vehicle, admin, non-chargeable quoting time) without leaving meaningful profit. 25–35% is a more sustainable working range for an established plasterer; higher on uncertain or awkward jobs.

How do I price a job where I can't fully inspect the walls before quoting?

Quote a range or a "subject to inspection on site" price with a stated day-rate fallback if condition is worse than assumed — e.g. "£900–£1,100 depending on wall condition confirmed on the day; day rate of £250 applies for additional bonding-coat work beyond initial assessment." This protects your margin without under- or over-quoting blind.

Is it worth taking on a mate/labourer to increase output?

Only if it lets you run two chargeable jobs in parallel or significantly speeds up a job where the client is paying for speed. A labourer at £100–£150/day only improves your margin if the extra output is genuinely billable — adding a second person to a single job you'd finish solo in the same elapsed time just adds cost without adding revenue.

Regulations & Standards