Roofing Quote Price Per Square Metre: A Line-by-Line Guide

A roofing quote price per square metre should be calculated on the roof surface — the sloped area you actually walk on and cover — not the building footprint. Take the plan area under the roof, multiply it by the pitch factor for the slope (a 30° roof is 1.155 × the plan area), add a waste allowance for hips, valleys and cuts (5–7% on a plain gable, 12–18% on a cut-up roof), and then keep scaffolding, fall protection, tear-off and tip fees out of the per-m² number entirely, as their own approved lines. That gives you a headline rate the homeowner can compare and a quote that still holds its margin when the roof turns out to be what roofs usually turn out to be.

Why the per-square-metre number has taken over

Homeowners do not compare roofers. They compare rates. Three quotes land in the inbox, each one a single total, and the only way to make them talk to each other is to divide by the area someone wrote down. So the customer does that division themselves, and the lowest number per m² wins the phone call.

You cannot fight that. You can only make sure your number is measuring the same thing the other two are, and that everything genuinely variable sits outside it where it can be discussed instead of absorbed.

Step 1: get the real roof area with a pitch factor

Floor area is not roof area. A 120 m² footprint with a 35° pitch is 146 m² of roof before you touch an eave or a verge. Quote the 120 and you have given away 26 m² of labour and material for free.

The pitch factor is straight geometry: 1 ÷ cos(pitch angle). Multiply plan area by it.

Then add the overhangs. Eaves and verges are real covered area and real work, and they are the first thing people forget: 400 mm eaves on a 12 m × 10 m building add roughly 9 m² of plan area before the pitch factor is even applied.

Write the method on the quote in one line: Roof area 146 m² = 120 m² plan × 1.221 (35°) + eaves. It takes ten seconds, it stops the argument later, and it quietly tells the customer the cheaper quote measured something else.

Step 2: waste is a function of roof shape, not a flat 10%

Every hip and every valley is a diagonal cut through a rectangular product. The offcut is usually scrap. A flat 10% applied to everything overcharges on simple roofs and bleeds you on complex ones.

• Plain gable, no penetrations: 5–7%
• Gable with dormers, chimney, roof windows: 8–12%
• Hipped roof: 10–14%
• Multiple valleys, L or T shaped, mixed pitches: 15–20%
• Any roof where the tile or sheet is a long-run bespoke length: add the cost of the wrong cut, because you cannot re-use it

These are working allowances, not laws of physics. Track your own: at the end of each job, log ordered quantity against installed quantity. After eight or ten roofs you will have waste percentages for your products and your crew that beat any rule of thumb in a manual, and you can stop guessing.

Metal sheet in bespoke lengths behaves differently again. Waste is not in the offcut percentage, it is in the ordering mistake. One mis-measured run on a long-sheet roof can cost more than the entire waste allowance on a tile job.

Step 3: scaffolding and fall protection come out of the m² rate

This is where most roofers lose money, because scaffolding scales with the perimeter and the eaves height, and the roof scales with area. Those two have nothing to do with each other. A long, low bungalow and a compact two-storey house can have identical roof areas and wildly different access costs.

Bury scaffolding in the per-m² rate and you have two problems. You lose the low bungalow to a competitor who priced access separately, and you win the tall awkward one at a loss.

Price it on its own terms:

• Erect and dismantle — per linear metre of facade, banded by height
• Hire period — per week beyond the first, because the delay is rarely yours
• Roof edge protection — per linear metre of eaves
• Safety rail, anchor points, harness lines — per job
• Extras that only exist on some sites — pavement licence, alterations to accommodate a conservatory, a bin lorry route, ground protection on a soft lawn

In Sweden, Arbetsmiljöverket is the authority here and work at height carries real duties, with fall protection required well before the heights people assume; the rules cover the planning of the work, not just the harness. In the UK the equivalent is the Work at Height Regulations 2005 enforced by HSE; in New Zealand it is WorkSafe. None of these treat fall protection as an optional extra you can trim to win a quote. If a competitor has hidden it, they have either priced it invisibly or they are not doing it.

Say so on the quote, without naming anyone: Scaffolding and edge protection are shown as separate lines so you can see exactly what your access costs. Any quote without them has either included them where you cannot check, or left them out.

Step 4: tear-off and tip fees priced by weight

Strip-out is the single most variable part of a roof and the part most often waved through with a round number. Price it by mass, because that is how the tip charges you.

Two things move this number hard. First, layers: a shingle roof stripped to deck can be one layer or three, and you will not know until you lift a corner. Second, mixed waste: clean concrete tile is one rate at the tip, but the moment old felt, nails and timber go in the same skip it reclassifies and the rate changes. Check your own tip's current per-tonne rates and their sorting rules before you build the line, because they move.

Put the assumption in writing: Priced on one existing layer of concrete tile, approx. 5.7 tonnes. If a second layer is found on strip-out, additional removal and tipping charged at [rate] per tonne, agreed with you before we continue. That is not a get-out clause. It is the honest description of a thing nobody can see from the ground.

Where the per-m² headline hides the losses

Anything that does not scale with area does not belong in a rate that scales with area. The usual suspects:

• Ridge, hip and verge — priced per linear metre. Two roofs of equal area can differ by 20 m of ridge.
• Valleys — per linear metre, and they are slow work
• Flashings, chimneys, soil pipes, roof windows — per unit
• Gutters and downpipes — per linear metre, often assumed by the customer and not by you
• Deck repair — provisional, per m², because you cannot see rot through tiles
• Battens and membrane — these do scale with area, so they can live in the rate
• Mobilisation, welfare, skip drops, delivery, crane or telehandler hire — per job

The test is simple. Ask yourself: if this roof were twice the area, would this cost double? If yes, it belongs in the m² rate. If no, it is a line of its own.

The line-item structure a customer can actually approve

Here is a structure that survives contact with a homeowner comparing three quotes. The headline rate stays visible and competitive. Everything variable is on the page, priced, and approvable.

Section 6 is the one that changes your life. A provisional sum is not a caveat, it is a pre-agreed price for a known unknown. The customer approves the rate on day zero, when they are calm and comparing, not on day three when the tiles are off and they feel ambushed. Roofers who do this get the ÄTA conversation over with before it becomes a dispute.

Deductions belong on labour, not on the headline

Swedish readers: ROT is a tax deduction of 30% of the labour cost on renovation work at the customer's home, with an annual per-person ceiling shared with RUT. It does not apply to material, scaffolding hire, or tip fees. Check the current ceiling and the qualifying rules at Skatteverket before you promise a net figure, because the amounts move.

Readers outside Sweden: the principle transfers even where the scheme does not. Any labour-only relief, VAT treatment or grant is calculated on a subset of your quote, which means your quote has to have that subset. If labour and material are fused into one m² rate, you cannot split them cleanly afterwards, and you end up either underclaiming or explaining an apportionment to someone who does not want to hear it. Split labour from material at quote time, always.

Staying competitive on the headline

The goal is not to be the cheapest per m². It is to be credibly comparable while everything genuinely variable sits outside the comparison. Three habits do most of the work.

• Show the area sum. One line of arithmetic signals that you measured the roof and the other quote measured the house.
• Name the assumption, price the exception. One layer, no rot, scaffolding for four weeks. Each with a rate if it turns out otherwise.
• Reconcile every job. Ordered vs. installed, quoted hours vs. clocked hours, estimated tonnage vs. weighbridge tickets. Do it ten times and your rates stop being opinions.

That last one is the hard part on paper. If you are already running your jobs in a system like OdinTask, the quote lines, the additional work approved mid-job, the clocked hours and the supplier invoice photographed from the roof all land against the same job, so the reconciliation is a report rather than an evening with a shoebox. However you do it, do it. A per-m² rate you have measured is a weapon. One you inherited from a mate in 2019 is a slow leak.

Build the quote so the customer can approve it in sections, and the headline number stops being a promise you have to keep in the dark. It becomes the one part of the job you can actually be confident about.

Try OdinTask free for 14 days and quote your next roof with the lines separated.