There are two published ways of measuring this and they give two different answers. On an installed per-square-metre basis, labour dominates. On an itemised project breakdown, materials and labour come out close, with materials ahead on natural slate. What both agree on is that it is not scaffolding, which is the answer most homeowners guess and the one the itemised quote pushes you towards.
The two published measures are not comparable
This has to come first, because the two figures are roughly four times apart and are routinely quoted as though they were interchangeable. Both are ex-VAT published cost-guide figures.
Checkatrade prices roofing labour at around £130 per square metre against roughly £50 per square metre for material supply. The £130 is an installed rate: it carries the firm's overhead, insurance, site time and margin as well as the wages. Across a 100 to 120 square metre roof it implies something like £13,000 to £15,600.
BestBuilders' itemised breakdown puts roofer labour at £2,000 to £4,500 for a two-person team over five to ten days. That is a bare wage line lifted out of a costed schedule, with scaffolding, waste and guttering priced separately alongside it. Over the same roof it is roughly a quarter of the first figure.
Neither is wrong, and neither can be added to or set against the other. A page that puts £130 per square metre and £2,000 to £4,500 in the same breath is comparing an installed rate with a wage bill.
On the per-square-metre basis, labour dominates
Take Checkatrade's installed rates at face value and the answer is labour, comfortably. Around £130 against £50 is close to a 70/30 split, and it holds for concrete and clay tile alike.
The reason is straightforward. A re-roof is almost entirely handwork at height. Every tile is placed by a person standing on a roof, in whatever weather turns up, and the parts that take longest, such as verges, valleys, ridge and lead around a chimney, are the parts you cannot speed up. On this measure the people cost more than the products on every covering.
On the itemised basis, materials edge ahead
Take the itemised breakdown instead and the ordering tightens and then reverses. Materials come to roughly £3,630 to £10,850 across the whole job: tiles or slates £2,500 to £8,500, membrane £350 to £600, battens £180 to £350, dry-fix ridge and hip £250 to £600, lead flashings £200 to £500 and sundries £150 to £300. Pure labour is the £2,000 to £4,500 above. On that reading materials are ahead at both ends of the range.
Whole-project percentages sit between the two views, at roughly 45% materials against 55% labour and services, because that split folds scaffolding, waste and guttering in with the wage line rather than pricing them separately.
So the honest answer is that published sources disagree about the split, and which one you use decides the headline. Where they converge is natural slate. Slates and tiles run £2,500 to £8,500 depending on covering, and at the top of that range the covering is the largest single number on the page whichever basis you read it on. On a concrete-tiled 1970s semi labour leads; on a slated Victorian terrace priced with a full new slate order, the slate does.
It is also why salvage matters. A roofer who strips carefully and relays the sound slates from your own roof is attacking the largest cost on the quote, not shaving the smallest. Ask whether the price assumes salvaged or all-new slate.
Scaffolding is not the biggest cost, though people assume it is
Scaffolding is 10 to 25% of a re-roof, and that holds on both of the bases above. A realistic London terrace figure is £800 to £1,500 for two to four weeks. Checkatrade's dedicated scaffolding guide prices a two-storey terrace over two walls at £800 a month, a two-storey semi over three walls at £875, and a three-storey semi at £1,100. All of those are ex-VAT cost-guide figures.
So why does everyone assume it is the biggest cost? Because of how it appears. Scaffolding is a large, round, separately itemised number attached to something that visibly does not fix your roof. Labour is spread across days and materials across dozens of line items; the scaffold is one conspicuous figure for a structure that goes up, sits there, and comes down.
Two further points are worth knowing. Checkatrade's own pages disagree on scaffolding, quoting £800 a month on the scaffolding guide and £900 a week on the roof installation guide. The dedicated February 2026 guide is the more reliable of the two. And safe access is not optional: the Work at Height Regulations 2005 require work at height to be properly planned and carried out with suitable equipment. The regulations do not name scaffolding, but on a full re-roof it is the usual way to satisfy them, so a quote that leaves it out is either understating the price or planning to work unsafely.
The lines that quietly add up
These are ex-VAT cost-guide rates, apart from the pavement licence, which is a fee set by the borough.
- Waste. Stripping the old roof generates one or two skips at £350 to £650, and a six-yard skip is £290 to £400 in London against £190 to £245 in the north.
- Soffit and fascia. £800 to £2,500, and much cheaper done while the scaffold is already up.
- Lead. Straight Code 5 flashing is £50 to £70 per metre; stepped flashing around a chimney is £80 to £120.
- The pavement licence. Scaffolding over a public footway needs a borough licence, typically £150 to £600 in inner London.
What this means when you read a quote
If one quote is dramatically cheaper, look at the labour line rather than the materials. Materials are broadly commodity-priced and hard to undercut honestly. A quote that lands well below the others has usually either cut days out of the schedule, left out scaffolding or waste, or is not carrying the insurance the others are paying for.