Updated 25 September 2026
Outbuilding supply / sub-board cost UK 2026
The going rate for outbuilding supply / sub-board in 2026 is £600–£1,000 (total, ex VAT). Below: a calculator, what the job involves, materials at three price levels, and the prep that changes the price.
Market band£600–£1,000
Worked example, 1 supply£662
Time on site1 days
Outbuilding supply / sub-board calculator
Price a real job freeUses your rates, your speed and your receipts.
Market band source: Trade2Base.
What the job involves
| Stage | Task | Typical time |
|---|---|---|
| work | Run SWA and glands | 0.2 h per supply |
| work | Fit sub-board and test | 4 h |
Materials at three price levels
| Material | Budget | Trade choice | Premium |
|---|---|---|---|
| Steel-wired armoured cable per m | £5 2.5 mm² 3-core SWA — Lights and a socket | £8 6 mm² 3-core SWA — Garden office loads | £12 10 mm² 3-core SWA — Heaters or EV later |
| Garage sub-board with RCBOs each | £80 4-way garage unit — Lights and sockets | £120 Metal sub-board with RCBOs — Proper protection | £180 Plus SPD and spare ways — Room to grow |
Trade prices ex VAT, estimates checked 2026-09-25. Log your receipts in Grafto and your own prices replace these.
What changes the price
- Cable run to the outbuilding (m)? big effect
- Trench? customer digs it · I dig it · clip to walls/fence big effect
Prep to look for
| Condition | Check | Effect |
|---|---|---|
| No RCD protection | board with no test button | RCD protection or consumer unit upgrade, if required £400–£700. No RCD protection: needed before adding to circuits |
| Plastic consumer unit | non-metal consumer unit | Plastic consumer unit: upgrade recommended |
| Low main fuse rating | main fuse label 60 A, old cut-out | 60 A main fuse or old cut-out: DNO upgrade may be needed for EV or heat pump |
Questions
How much does outbuilding supply / sub-board cost in the UK in 2026?
The researched market band is £600–£1,000 (total, ex VAT), from Trade2Base. A worked example of 1 supply comes to about £542–£832 across budget, trade and premium materials.
How long does outbuilding supply / sub-board take?
The worked example of 1 supply takes about 1 working days.
What changes the price of outbuilding supply / sub-board?
Mainly cable run to the outbuilding (m), trench, plus any prep found on site: no rcd protection, plastic consumer unit, low main fuse rating.