Making sure there is a profit in your renovation before you buy is one of the most important disciplines in property investing.
But, surprisingly, this is also the one thing people are most likely to fudge.
You have to build the profit in before you buy.
Not hope for it.
Not assume it is in there somewhere.
Not tell yourself you will “probably be fine”.
Build it in.
As a number.
In the appraisal.
Before you make the offer.
If the profit is not visible at that stage, it is highly unlikely to appear later by magic.
Start with the end
The simplest way to think about this is to start with the finished value and work backwards.
What is the property likely to be worth once the work is done?
Not the most flattering figure.
Not the highest asking price you have seen for something vaguely similar.
The realistic end value, based on what comparable properties are genuinely achieving in that area, in that condition, in the current market.
This point matters because people are often most generous with themselves at exactly this stage. They want the deal to work, so they instinctively reach for the optimistic number.
That is dangerous.
Then deduct everything
From that realistic end value, you then deduct every cost associated with the project.
Purchase costs.
Refurbishment costs.
Finance costs.
Selling or refinancing costs.
And, importantly, your profit.
Not “whatever is left at the end”.
The profit you want the project to produce.
That should be treated as part of the appraisal discipline, not as a pleasant surprise if the job goes well.
What “everything” really means
Buying costs are easy enough to identify. Legal fees, stamp duty, surveys, broker fees if relevant.
Refurbishment costs need more care. They should come from current local quotes wherever possible, not rough memory or something somebody said at a networking meeting last year. Labour, materials, professional fees if needed, and all the less glamorous bits that have a habit of turning up on the bill later.
Then comes contingency.
A proper contingency.
Not the one you quietly shrink because otherwise the deal stops looking attractive.
On a refurbishment project there is almost always something that was not obvious at the viewing stage, or something that turns out to be a bit more involved than expected. If you have not allowed for that, your figures are already living on borrowed time.
Finance costs also need to be there in full. Not just the purchase stage, but for the whole life of the project. If the deal takes longer, which it often does, those costs keep going.
And if you are using your own money rather than borrowing, there is still an opportunity cost.
The number that matters most
Once all of that has been deducted, what you are left with tells you the maximum you can sensibly pay for the property if the project is to do what you need it to do.
That is the number that matters.
Not the asking price.
Not what the agent tells you it ought to make.
Not what you would like to pay because you can see potential.
The discipline is in respecting the number you arrived at.
That is where many people go wrong.
They do the sums, sort of.
Then they offer more because they do not want to lose the deal.
Or they shave the works cost a bit.
Or they soften the contingency.
Or they quietly reduce the profit target.
None of those moves looks especially dramatic in isolation.
Together, they can leave you exposed before the work has even started.
What actually goes wrong
The pattern is usually the same.
An investor likes the property.
They convince themselves there must be a deal in it somewhere.
They nudge the end value up.
They nudge the costs down.
They decide contingency is probably overcautious.
And by the time they are done “adjusting”, the project works beautifully.
On paper.
As long as nothing goes wrong.
On a refurb, that is not a sensible bet.
Walking away is part of the strategy
Sometimes the most profitable decision you make is the decision not to buy.
That can feel frustrating. Especially if you have spent time viewing the property, thinking it through, maybe even getting quotes. But it is infinitely better than spending months of time, effort and money on a project that never really had enough margin in it to begin with.
A project should not need wishful thinking to make it profitable.
The numbers need to stack honestly.
If they do, then you may have something worth pursuing.
If they don’t, then however attractive the property looks, it is probably not the right deal.
Profit first.
Then everything else.
Here’s to successful property renovating.
Peter Jones (ex) Chartered Surveyor, author and property investor
www.thepropertyteacher.co.uk
By the way, I’ve completely rewritten and updated my course for 2026, The Successful Property Renovator’s Workshop — a comprehensive guide to renovating properties properly and profitably, based on my own experience across well over 150 projects over thirty years.
For more details please go to: https://thepropertyteacher.co.uk/the-successful-property-renovators-workshop/
