From bill of quantities to material order sheet

To turn a bill of quantities into a material order, take each measured quantity, multiply by the manufacturer's coverage rate, add a waste allowance, then round up to the packs, pallets or lengths your merchant sells. Group the list by supplier and delivery date. The bill tells you what's built; the order sheet tells you what to buy.

Why doesn't the bill of quantities tell you what to order?

Because a bill measures the finished work, not the materials. Under the RICS measurement rules, a bill lists items in units such as m², m, m³ and number: "concrete interlocking tiles, 40° pitch, 80 m²". It doesn't say how many tiles, battens, nails or clips that takes, or allow for waste and offcuts.

So you need a conversion step. It's also where money goes missing. Over-ordering ties up cash and fills the skip; under-ordering costs a day on site waiting for a delivery.

How do you convert quantities to materials?

Four steps, in this order, for every line.

1. Find the coverage rate.

   From the manufacturer's data sheet or product page: tiles per m², sheets per m², litres per m². Coverage often changes with the spec, such as tile headlap or joist centres, so check the spec matches.

2. Multiply.

   Quantity × coverage gives the net number of units.

3. Add waste.

   As its own line. Cutting, breakage and offcuts vary by material and by how complicated the job is. Five to ten per cent is common for bricks and tiles; a roof with hips and valleys needs more than a plain gable.

4. Round to what you can buy.

   Pallets, packs, sheet sizes and lengths. Then ask about loose units or part packs before rounding a whole extra pallet.

A worked example: re-roof and a new ceiling

Here's a conversion for a small job: a re-roof of two slopes totalling 80 m² in interlocking concrete tiles, and a new plasterboard ceiling in a 4 m × 3 m room.

If loose tiles aren't available, five pallets gives 960 tiles: 128 more than you need. At that point it's cheaper to ask the merchant about a return than to store them.

What should a material order sheet include?

Everything a merchant needs to pick and deliver without ringing you back. Copy this and fill it from your take-off or the bill.

Job: job name and site address
Site contact: name and mobile   Delivery access: e.g. narrow lane, no artic; crane offload needed
Order ref / PO: number   Account: merchant account number

Phase 1, deliver date, AM/PM
Item | Product and spec | Bill ref | Net qty | Waste | Order qty | Unit
1 | Marley Modern tile, smooth grey | H60/1 | 792 | 40 | 4 pallets + 64 loose | tiles
2 | Treated batten 38 × 25 mm to BS 5534 | H60/2 | 232 m | 23 m | 255 m | m

Phase 2, deliver date
3 | Gyproc WallBoard 12.5 mm 1200 × 2400 TE | K10/1 | 4.17 | 0.41 | 5 | sheets

Please confirm prices, stock and delivery date before dispatch. Part-pack or loose units preferred where available. Return policy for unopened full packs: ask.

The bill ref column is the useful one. When the invoice comes in, you can check each line against what the job was priced for, and see straight away if the merchant's price has moved since you tendered. The guide to spotting supplier price rises on invoices covers that check.

How do you get prices from several merchants?

Send the same order sheet to each and compare line by line, not on the total. One merchant may be cheapest on tiles and dearest on battens. A national groundworks and civils firm we spoke to described ringing round for one job: "I had seven suppliers for a three-day job", around 20 calls. The same firm told us switching suppliers cut its material costs by about 30% on £300,000 to £400,000 a year of materials. That's one firm's result, not a typical saving, but it shows what comparing properly can be worth.

Getting material prices from several merchants covers how to do it without the phone calls, and material markup for tradespeople covers what to add when you pass the cost on.

Where do conversions usually go wrong?

In the coverage rate and the spec. A roofing and cladding firm in Ireland found an AI-assisted check corrected a board coverage figure from 0.75 to 1.44 m² per board. At the wrong figure, they'd have ordered nearly twice the boards they needed. Always take coverage from the product specified, and check it against the bill's description: headlap, joist centres, board size and fixing pattern all change the number.

The other common miss is the items a bill measures as one line but you buy as several: the tiles are in the bill, but the ridge, dry verge, underlay, clips and nails need their own lines on the order. If your quantities came from your own measuring, the take-off guide shows how to set them up so the conversion is easy. If you're pricing a client's bill, filling in a schedule of rates covers building the rates from the same figures.

Common questions