Job costing and cash flow for small builders

“Profitable jobs, empty bank account”

A small building firm wins a two-month flat refurbishment. The quote stacks up, the margin looks fine, and the client signs. Two weeks in, the familiar squeeze starts: merchants need paying, the crew are waiting for wages, plus fuel, sundries, skip hire and tool hire. On paper the job is still profitable, but the business account is close to zero.

That is not always bad pricing. Very often two simple views are missing:

• job costing - tracking labour, materials, subcontractors, plant and a share of overhead against that specific job
• cash flow - looking at when money actually leaves the business and when it comes back in from the client

Margin protects your profit at the end of the project. Cash flow protects your ability to survive while the job is running.

In refurbishment work, cash gaps appear quickly. You usually buy materials up front, pay labour regularly, and the client payment is tied to stages or the end of the works. Some contracts also have retentions or small holdbacks until completion or snagging is done. Industry research shows that in construction, subcontractors can wait around two to three months between doing the work and getting paid.

So “it will sort itself out” is not a plan. Better to see the numbers early.

Example: six-week flat refurb

You have a six-week programme. In weeks 1 and 2 you pay for most materials and the first works. In weeks 3 and 4 you hit peak labour. The client only pays the main chunk in week 6 after a stage sign-off.

On the quote everything looks fine. In reality you are funding several weeks out of your own pocket. If you are also running a bathroom refit and a small extension at the same time, even decent jobs can create a serious hole in your cash.

The answer is not complex accounting software. You just need a simple job cost sheet tied to a weekly money plan.

Simple job costing you will actually keep up

Job costing does not need a huge list of cost codes. For a small builder or refurbishment crew, a handful of cost groups and consistent habits are enough.

Most firms do well tracking:

1. Labour - your own time, employees and regular gangs
2. Materials - merchants, DIY stores, online orders
3. Subcontractors - electrician, plumber, tiler, joiner, glazier, stone work and similar trades
4. Plant and transport - tool hire, scaffold, skips, deliveries, fuel
5. Allocated overhead - a simple share of fixed costs if you use that in your pricing

With that split you can see quickly if the issue is hours, material prices or a subcontractor you under-allowed.

Cost codes without corporate jargon

Big contractors run detailed cost-coding structures. A small firm usually only needs 15-25 work items, ideally named the same way you write your quotes:

• strip-out / demolition
• electrical first and second fix
• plumbing and heating
• walls and ceilings
• studwork and drylining
• screeds / floor build-up
• tiling
• floor finishes
• painting and decorating
• kitchen install
• bathroom second fix / sanitaryware
• cleaning and sundries

The key is that the same wording appears on the quote, in your estimate and in the job cost report. Then you are not guessing a month later where to put the invoice for adhesive, metal stud or an extra day on site.

What a job cost sheet looks like

A basic spreadsheet is enough. Put your stages or cost codes in rows, and columns such as:

• budget labour
• budget materials
• budget subcontractors
• budget plant / transport
• total budget
• actual costs in the same groups
• variance: budget minus actual

At the bottom add:

• contract value
• total planned costs
• total actual costs
• gross profit in pounds and as a percentage

That is your core job cost report: contract value, cost categories, estimate vs actual and over / under budget.

You are not trying to replace your accountant. You are trying to manage the job before the profit leaks away in day-to-day decisions on site.

Habits that make the numbers useful

The sheet only works if data goes in regularly. A few practical habits:

• Write the job name on every invoice or receipt.
• Log labour hours daily or at least weekly.
• Allocate materials to the right stage where it matters, for example tiling rather than painting.
• Update your costs at least once a week.
• Compare actuals with your quote, not just with the bank balance.

If you use a tool like Bulido, you can keep quote, scope, costs and payments in one place. The same idea works perfectly well in a spreadsheet, as long as you are consistent.

From costs to cash: a weekly money plan

“Is the job profitable?” is only half the question. You also need to ask: “In which week will I run short of cash?”

Profitability shows the overall result after the project. Cash flow shows the timing: money out first, then money in - or the other way round if you set up your payment terms well.

You can have negative cash flow on a profitable job when:

• the client pays later than agreed
• you buy large amounts of material far in advance
• variations are not priced and invoiced quickly
• part of a payment is held back as retention until completion

How to build a simple weekly cash forecast

Take your programme of works and break it down by week. For each week, list:

• expected material spend
• expected labour costs
• payments to subcontractors
• any big plant or transport costs
• planned invoices and payments from the client

Then calculate:

cash in minus cash out = weekly balance

Add a running total. That cumulative figure shows where the deepest dip in cash sits.

Example: six-week kitchen refit

Say you have a kitchen contract at £50,000 with planned costs of about £40,000. Nice margin, but the cash does not arrive in a straight line.

You finish £10,000 up, but in week 2 you are £26,000 down. Run three similar jobs side by side and that “temporary” gap becomes a serious problem.

The forecast does not need to be perfect to the pound. Its job is to show where the big negatives sit so you can react early: move a material order, arrange a stage payment, invoice a variation sooner or renegotiate the payment schedule with the client.

Ways to shrink the cash gap

There is no one safe template that fits every contract. Local rules, tax and invoicing methods make a difference, so check details with your accountant or adviser if needed. Operationally, though, there are plenty of things you can do.

Taking some money up front

Many builders agree a payment before starting on site or before ordering major materials. To keep it professional:

• show which materials or bookings that money covers
• write it clearly into the quote and client agreement
• tie it to a specific trigger, such as “to order kitchen units” or “to book the start date”, rather than “because that is how we work”

In your cash flow table, that upfront payment can cover part of the first big material hit instead of you funding it all.

Milestone billing linked to real site events

Instead of one big invoice at the end, many firms use staged or progress billing. It works best when you link it to tangible milestones, not just percentages:

• after strip-out and first fix are complete
• after tiling, plastering and joinery are finished
• after kitchen installation
• after final snagging and handover

The client can see what they are paying for, and you can line those milestones up with your cost profile. That reduces the risk that you are acting as the bank for most of the project.

Variations without chaos

Extras are where both margin and cash flow often fall apart: extra sockets, different tiles, moving a wall, “while you are here, can you just do the hallway as well”.

Put a simple process in place:

1. write down the scope briefly by email, message or app
2. state the price for labour and materials
3. agree when it will be paid
4. add the revenue and cost to the job cost sheet
5. update the job’s cash forecast

You do not need heavy paperwork. The point is that extra work is not just a chat on site that leaves you with costs but no invoice.

Invoicing and chasing as a routine

Cash flow planning only helps if invoices actually go out and get followed up:

• raise the invoice as soon as a stage is finished
• once a week, check what needs to be billed and what is overdue
• send reminders that are calm, clear and in line with what you agreed

You will never remove late payments completely. Clear milestones, prompt invoicing and polite but firm chasing reduce the chance that you only spot the issue when the account is empty.

Tools and a weekly finance check-in

You do not need heavy software from day one. Start with a spreadsheet with three tabs:

1. Quote & budget - planned costs by stage or cost code
2. Actual costs - labour, materials, subcontractors, plant
3. Cash flow - weeks, cash out, cash in, cumulative balance

As you add more live jobs, spreadsheets can get painful: different versions, no change history, and quote, costs and payments are not properly linked. At that point it is worth looking at light job management tools. Bulido, for example, can tie together your quote, scope, materials, job costs and payments into one story for each project.

The principle does not change: first a simple way of thinking, then a tool that speeds it up.

Also set a fixed weekly 30-minute finance session. In that half hour:

• attach new invoices and receipts to the right jobs
• enter the latest labour hours
• check which lines are over budget
• review the 4-6 week cash forecast
• make a list of invoices to send and payments to chase
• decide if you need to move a purchase, adjust the programme or talk to a client

This does not have to be perfect. The main thing is consistency. After a few weeks you start spotting problems much earlier: too many hours on tiling, material prices higher than allowed, a payment running late, a stage that should already be invoiced.

Start with one live job

Here is a simple plan for the coming week:

1. Pick one active project that still has a few weeks to run.
2. Set up a job cost sheet: stages, budgets, actuals and variances.
3. Add a weekly cash table: cash out, cash in, balance.
4. Put a recurring 30-minute finance slot in your diary.
5. After two or three weeks, look at what you have learnt: where margin is slipping and where the cash gap is worst.

You do not have to rebuild your whole business overnight. One well-tracked job is often enough to change how you handle the next ones: you order materials differently, price extras quicker, and negotiate your payment stages with more confidence.

A small building firm does not need big-contractor accounting. It needs a clear view: what it was meant to cost, what it actually costs, when money leaves and when it comes back. That is enough to spot profit leaks early and stop “profitable” jobs from draining your cash halfway through.