An instant estimate is only as good as the rates behind it. You already know what jobs cost. This guide turns that into a short rates sheet an online estimate can use, and checks it against work you’ve actually priced.

What a rates sheet needs

  • A rate per m² fitted for each covering, as a low and a high figure: felt, EPDM rubber and GRP fibreglass for flat roofs; tiles and slate for pitched roofs.
  • A minimum job, so a tiny roof never shows a silly figure.
  • Allowances for the things that change the price on the day: chimney stacks, roof windows, difficult access, a steep pitch, and new roofs as opposed to replacements.
  • Repair bands rather than per-m² rates, because repairs are priced by the job, not the area.
  • Your VAT position, so every figure shown is on the same basis.

Start from jobs you’ve already priced

Take ten or so recent quotes for the same kind of work. For each, take the price for the main covering, leaving out extras such as a chimney or a Velux, and divide it by the roof area. The spread of those figures is your range: the cheaper end is your low rate, the dearer end your high rate. If one job is far outside the rest, find out why before letting it move the range.

A worked example, with made-up rates: a felt flat roof at £90 to £120 per m² fitted. A garage roof of 18 m² comes out at 18 × £90 = £1,620 up to 18 × £120 = £2,160. Firstprice rounds the range outwards to the nearest £50, so the homeowner sees £1,600 to £2,200.

Roof area means the roof, not the floor plan

For a flat roof, area and footprint are close. For a pitched roof they aren’t: the slopes cover more than the ground the house sits on, and the steeper the pitch, the bigger the difference. Your rates should be per m² of actual roof surface, and the estimate should say so, so that homeowners and your rates are measuring the same thing.

The minimum job

Per-m² pricing breaks down on very small roofs. A 4 m² porch at £90 per m² comes to £360, which may be below what it costs you to turn up. A minimum charge, say £750, means the estimate shows that instead. Set it at the smallest job you’d actually take on.

Allowances and extras

Chimney stacks and roof windows

A fixed allowance each, as a range, for example £350 to £750 for flashing round a chimney stack. Homeowners mention these in their own words (“there’s a chimney”, “two Veluxes”), so the estimate should recognise the usual ways of saying them.

Difficult access

A per-job allowance for scaffolding or awkward access, such as a three-storey house or no way round the back.

Steep pitch and new roofs

A percentage uplift works better than a fixed sum here, because the extra labour grows with the size of the job.

Things you won’t price blind

Possible asbestos, listed buildings, conservation areas and structural damage need someone on the roof. Mark them as survey-only, so the estimate tells the homeowner a survey is needed rather than showing a figure.

Repairs

Leak finding, covering repairs and flashing repairs vary too much by area to price per m². Give each a band, such as a typical low and high for that kind of repair, and let anything bigger go to a survey.

VAT

Decide whether your figures include VAT, exclude it, or whether you’re not VAT registered, and say so next to the price. A homeowner comparing your estimate with a written quote needs to know they’re on the same basis.

Check it before it goes live

Run your last ten quotes through the rates and compare. If the ranges sit around what you actually charged, you’re done. If a type of job comes out consistently high or low, adjust that rate and run them again. It’s far better to find a wrong range on paper than from a customer. With Firstprice, this check is part of setting up.

Keep it up to date

Materials and labour move. Look at your rates whenever your own prices change, and at least every few months. With rates held centrally, a change takes effect without anyone touching your website.