Growing from 5 to 15 staff without an office manager

You can grow from 5 to 15 staff without an office manager if every admin job has a written system and someone, or something, that does it without you. Hiring is one answer, but at £30,000 a year an office manager costs about £34,500 once employer National Insurance and pension are added. First count what your own admin hours already cost.

Why does admin get worse between 5 and 15 people?

Because every new person on the tools adds paperwork that lands on the owner: timesheets, materials orders, site photos, RAMS, holidays, and more jobs to quote and invoice. Up to about five people you can carry it in your head. Past that, it spills into evenings.

A groundworks and civils firm we spoke to, seven staff plus four or five subbies, turning over about £1m a year, was still running on pen and paper. The owner's verdict: "I'm maxed out. I can't get any bigger." A metal fabrication firm with eight staff had the opposite problem: their office manager had left, and the owner described the result as "a bit carnage". Both are the same risk: the admin lives in one head.

What does an office manager cost?

More than the salary. Here's an example at £30,000 a year, using 2026 to 2027 employer rates. Use the salary you'd have to pay locally; this is an illustration, not a market rate.

Worked example

Office manager on £30,000 vs the owner's own admin hours

Example office manager salaryyour local rate will differ	£30,000.00
Employer National Insurance15% × (£30,000 − £5,000)	£3,750.00
Minimum employer pension3% × (£30,000 − £6,240)	£712.80
Yearly cost of the hire	£34,462.80
Owner's admin now16 hrs a week (2 days) × 48 weeks	768 hrs
Value of those hours768 × £45 charge-out rate	£34,560
Owner's admin, valued at his rate	£34,560

The two numbers come out about the same, which is the point. Your current admin isn't free: it's paid in hours you could bill, quote or sleep. Put your own figures in the calculator.

Calculator: What admin costs you

Admin hours a weekEvenings and weekends counthrs

Weeks a year

What your hour is worthYour charge-out rate£

A year–

Your numbers, not a promise. Change any figure to match your firm.

Which admin tasks should you systemise first?

The ones that touch cash: quoting, supplier bills and invoicing. A slow quote loses the job; an unchecked supplier bill loses margin; an unsent invoice loses cash flow. Scheduling and compliance come next.

Write down who does each one. "Me" is an answer, but it's the answer you're trying to change.

How do you take admin off the owner without hiring?

Give each task a system that runs without your memory. That can be a part-time bookkeeper, a virtual assistant, better software, or AI that drafts and you approve.

1. Count your hours for two weeks.

   Write down every admin task and how long it took. Most owners guess low.

2. Pick the three biggest tasks.

   Usually quoting, bills and chasing.

3. Write the system down.

   One page per task: where things come in, what gets done, where the result goes, how you check it.

4. Hand it over.

   To a person, a tool or both. Keep approval for anything that sends money or a price.

5. Check weekly for a month.

   Fix what breaks, then check monthly.

A high-end renovation builder with four or five staff went from about two days a week of admin to about 30 minutes a day, mostly on his phone, by moving quotes, supplier bills and job costs into a system he approves rather than does. He'd described his admin before as "a bit of a shambles".

Whatever I was bringing in, was paying out.

That roofer had every job in one spreadsheet and no way to see which jobs made money. Systems aren't only about time: they're how you find out where the money goes. See owner as the bottleneck for the wider picture, and the live guide on scaling without hiring.

When should you hire an office manager anyway?

When the work needs a person: answering the phone all day, dealing face to face with clients, chasing on site, or covering when you're away. If your clients are landlords and agents with dozens of properties, someone has to own that relationship; see landlord customers. Hire for judgement and people, and systemise the typing. An office manager who joins a firm with written systems gets productive faster, and the firm doesn't fall apart when they leave.

Systems also matter if you ever want to sell. A buyer pays for a business that runs without the owner; see the records a buyer wants.

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Where Nexley fits

Nexley is the AI back office for UK trade firms: five AI assistants run your tenders, quotes, buying, scheduling and invoicing. It connects to the tools you already work in, you run it all from WhatsApp, and you approve everything. £799 a month.

Nexley does the office work a growing firm would hire for: drafting quotes from voice notes, filing supplier bills against the right job, sending invoices and chasing them, and keeping schedules. It works over WhatsApp, so engineers send timesheets and photos from site, and you approve anything that goes out.

Start 7 days freeSee back office automation

Common questions

Sources

1. GOV.UK: Rates and thresholds for employers 2026 to 2027
2. The Pensions Regulator: Making contributions to your pension scheme
3. GOV.UK: Holiday entitlement

Every rule, rate and date above was checked against these sources on the date shown at the top.