Construction companies that sub out all the work make money on the spread - the gap between what the client pays and what the subs charge. That mechanic is construction arbitrage: win the job at market rate, sub it out at trade prices, keep the difference. On residential work that spread typically runs 20-35% before overhead comes off.
(Figures in USD - the model and the maths work identically in any currency.)
How the construction arbitrage spread works in plain numbers
The mechanic is straightforward once you see it written out.
You quote a bathroom renovation at $12,000. That is what the client pays, all-in.
You line up a plumber, a tiler, and a painter. Their combined invoices come to $8,500. Materials you buy at trade cost add another $1,200. Total out: $9,700.
Your spread on that job: $2,300 - just under 20% of what the client paid.
Out of that $2,300 you pay for your time quoting and coordinating, a share of your insurance, and a share of any admin or software costs. What remains is profit.
That is construction arbitrage in one job. You never picked up a tool on that bathroom. The money came from managing the outcome, not from doing the tiling.
What you are actually being paid for
This is the question most people ask when they first see the model: if the sub does the work, what did you do to earn that $2,300?
Quite a lot, as it turns out.
You took the risk. The client contracted with you, not with the plumber. If the plumber ghosts the job in week two, that is your problem. If there is a defect six months later, the client calls you. That accountability has a price, and the spread is part of it.
You coordinated the trades. Getting a plumber, a tiler, and a painter to show up in the right order - plumber finishes rough-in before the tiler goes in, tiler finishes before the painter touches a wall - requires active management. It is not passive. Miss the sequence and a trade stands idle on a day rate while another catches up.
You gave the client one throat to choke. From the client's side, dealing with one contractor who handles everything is worth paying a premium over managing three separate tradespeople themselves. That premium is the market rate you quoted above what the subs charge.
You absorbed the quoting and paperwork overhead. The time to visit the site, write the quote, negotiate, raise contracts, chase subs for certificates, and manage the invoicing is real overhead. It comes out of the spread.
None of this is free. The spread compensates for all of it. The model works because the market values a managed, guaranteed outcome more than a loose collection of individual trades.
A real worked example - full cost stack
I will use a project from my own business to show the full picture, because the topline spread number always looks better than the reality once you account for everything.
Say I win a property maintenance contract covering a full internal refurbishment - new kitchen, bathroom, replastering, decoration.
| Line | Amount |
|---|---|
| Quoted to client | $28,000 |
| Subcontractors (kitchen fitter, plumber, plasterer, decorator) | $16,400 |
| Materials (bought at trade and marked up 15%) | $4,600 |
| Skip hire, site visits, sundries | $400 |
| Total out | $21,400 |
| Gross spread | $6,600 (23.6%) |
Out of that $6,600 comes a share of my annual insurance premium, a share of my software and admin costs, and the hours I spent quoting, coordinating site, and managing snagging. Realistically, $1,200-$1,500 of real overhead comes off that job.
Net on this job: roughly $5,100-$5,400. Not bad for a job I did not lay a single tile on.
At 20-35% gross margins on residential work, a solo operator running four to six jobs like this a month is building a real income - without an employee on payroll or a van in the yard.
"But you are just a middleman"
This is the objection every new operator hears, usually from a tradesperson who feels cut out of a margin they think they deserve.
The middleman framing misses what the middle actually does.
Every industry has layers between the person who does the work and the person who pays for it. A restaurant marks up a chef's labour and ingredients 300%+ and nobody calls the owner a middleman for owning the kitchen. An estate agent takes a 2-3% commission for connecting a buyer and seller. A recruitment firm takes 15-25% of a placed candidate's first-year salary.
The construction contractor marks up subcontracted work 20-30% and provides: legal accountability, project coordination, a warranty, insurance, and a single commercial relationship for the client. That is a legitimate service.
The sub can always go direct to clients. Some do. But most do not, because running their own sales pipeline is a second unpaid job, and most of their work comes from main contractors - which is to say, from people running exactly this model.
The spread is not extracted from the sub. The sub quotes their price for the work. You quote a higher price for the managed outcome. The difference is what the market pays for the layer you add.
How this scales
The spread model has a structural advantage over being a sole trader doing the work yourself: the income does not stop when your hours do.
If you are on the tools personally, your revenue is capped at what you can physically produce in a week. At $400 a day that is $2,000 a week, $100,000 a year if you never take a day off.
Running the arbitrage model with four active subs, each generating a 25% gross margin on $3,000-$5,000 worth of weekly work, you are looking at $3,000-$5,000 gross per week without touching a tool. Scale the sub bench, scale the income.
I went from one handyman to two, then added a plumber because plumbing jobs paid the most. Then I found plumbers who had their own transport so I did not have to be on site. Then more handymen. Then I tried subcontracting most of my jobs on a trip to Scotland - away from my usual area, running jobs remotely by necessity. When I came back, I kept doing it. Within a year I had subcontracted everything.
Each step scaled the spread without scaling my hours. That is the structural point most people miss when they ask how construction companies make money by subbing everything out. The answer is: more efficiently than if they did it themselves.
What takes a bite out of the spread
The gross spread is not what you keep. Things that erode it:
Insurance. Public liability and professional indemnity are non-negotiable, and they are a real overhead. Budget a share of your annual premium into every job.
Snagging and defects. If a sub's work fails inspection or the client calls back six months later, the fix comes out of your spread. Good vetting and tight sub contracts reduce this, but they do not eliminate it. How to vet subcontractors covers the due diligence that keeps this cost down.
Quoting time. Lost jobs cost you quoting time for zero return. Track your conversion rate. If you are losing seven in ten quotes, your pricing or your targeting is off.
Payment timing. You often pay subs before the client pays you. That gap is a cash flow cost, even if it does not show up on the job margin.
Retention (UK). Contracts often hold 5% back until defects period ends - up to a year after practical completion. Half your spread on a job can sit locked in a retention account for twelve months.
Run the net margin, not just the gross. The model still works - but not at the gross number you start with.
Why this is how large construction works too
It is worth saying clearly: the biggest general contractors in the world operate this model. The main contractor on a $50 million commercial development does not employ electricians, plumbers, structural steel erectors, or fit-out crews directly. They win the contract, write the subcontracts, manage the programme, and keep the spread on each package.
The scale differs. The mechanics do not.
Small operators running $500,000 a year in residential work and the construction arms of multinational developers are doing the same thing: intermediating between a client who wants a managed outcome and specialist trades who provide the labour. The spread is the business.
If you want to understand the full model from first principles, the pillar explains what construction arbitrage is and how it works. For what realistic annual income looks like once the model is running, how much money construction arbitrage makes runs the numbers at different job volumes and margins.
The book - THE FAMILY SECRET - How Construction Arbitrage Really Works - covers the full arc from first job to running it as a system. Coming soon.
Last checked: 5 August 2026.
Frequently asked questions
If subcontractors do all the work, what exactly does the main contractor do?+
The main contractor wins the work, signs the contract with the client, takes on the legal and financial liability, coordinates the trades, and guarantees the result. That accountability is what the client is paying for - and it is worth real money.
Is it legal to make money from the spread between your price and the sub's price?+
Yes. This is standard commercial practice. You present one price to the client. What you pay subs is a separate agreement. The spread is your gross profit. Every industry does some version of this.
How big is the spread typically?+
On residential small works and renovations, a 20-35% gross margin on total job value is normal. On a $10,000 bathroom renovation, that might mean $2,000-$3,500 in gross profit before your overhead. Smaller jobs can run higher because the coordination effort is proportionally heavy.
Does the client know you are subcontracting the work?+
In most markets you are not required to disclose which specific trades you use - and in many cases clients do not care, because they are hiring you for the outcome and the guarantee. Check the legal position in your market, as disclosure rules vary.
What happens if the subcontractor does a bad job?+
The liability sits with you, not the sub. You fix it, at your cost if the sub won't, and you sort out the commercial dispute with the sub afterwards. That liability is a real risk - and it is also the economic reason the spread exists.
Can you actually make a living doing this?+
Yes. At 20-30% gross margin on residential work, a solo operator running $400,000 in annual jobs keeps $80,000-$120,000 gross before overhead. After insurance, admin, and tax, that nets down - but it compares well to trade wages for someone not picking up tools every day.
Mohamed El HadriCo-Founder
I'm a co-founder of several construction companies. I built a construction business from a 30-van operation into a lean model with 1,500+ subcontractors in the database - winning the work as the main contractor, subbing it out, and running it as a system from a laptop across multiple countries. I write this site from what actually works.
@mointhemarket · 30k followers on Instagram →Run the model with people who already do
Reading the method is step one. Inside Construction Arbitrage Players you connect with players from around the world who run construction arbitrage every day and make real money from it - share your deals, get answers, and get in the game. Founding-member access is open now.
For the operator life and the inside story, see Contractor Club.
The Family Secret - how construction arbitrage really works - is coming soon.
A construction business built this way is a sellable asset
Systems, subs and margin - that is exactly what buyers pay for. If you own a construction or trade business and the exit is on your mind, list it on ContractorExit, the marketplace for buying and selling trade businesses. The valuation is free, so you find out what it is worth before you decide anything.
Get the Construction Arbitrage playbook
One sharp email a week: real numbers, live deal breakdowns, and the systems that let you run jobs you never visit. No fluff, unsubscribe anytime.
