If you ask most people why renovation projects go wrong financially, they will usually point to the obvious things.
The costs overran.
The market moved.
The builder let them down.
And of course those things do happen. Sometimes one of them is the problem. Sometimes two or three of them turn up together, which is always fun.
But in my experience, they are very often not the real reason a project fails to make a proper profit.
The real reason is usually much simpler than that.
The profit was never properly built in at the beginning.
That is not always what people want to hear, because it sounds less dramatic. It is much easier to blame the builder, or bad luck, or the market, than it is to admit that the deal never really stacked up properly in the first place. But I have seen this pattern often enough over the years to know that it is very common.
An investor finds a property they like. They can see the potential. They can imagine what it will look like once it is done up. They can almost see the profit before they have even done the sums.
And that is where the trouble starts.
Because once somebody wants a property badly enough, it becomes very easy to start trying to make the figures fit instead of checking whether they actually do fit.
The end value gets pushed up a bit.
The likely refurb cost gets trimmed down a bit.
The contingency gets squeezed because otherwise the deal starts looking less attractive.
The profit is not really built in as a proper figure at all. It is just whatever they hope will be left over at the end once everything has been paid for.
That is the wrong way round.
If you are going to renovate property for profit, the numbers need to work before you buy, not afterwards.
And that means doing the sums in a way that is honest rather than hopeful.
The starting point, in simple terms, is the likely end value once the works are 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 actually achieving in that area.
Then you work backwards.
Take off the purchase costs.
Take off the refurbishment costs, and include a proper contingency because there is almost always more to do than you first thought.
Take off the finance costs for the full period of the project, not just the purchase stage.
Take off the selling costs, or the refinance costs if that is your exit.
And then take off the profit you want to make.
Not the hoped-for profit. The planned profit.
That point matters quite a lot, because I do not think enough people do it.
They look at profit as though it is the nice surprise at the end if everything goes well. I think that is a mistake. The profit needs to be there in the appraisal from the start. In other words, once you have deducted everything else, there still needs to be enough room left in the deal to justify doing it.
If there is not, then however attractive the property may look, it is probably not the right deal.
And once you have worked out the maximum you can sensibly pay, the discipline is sticking to it.
That is another point where people come unstuck.
They know roughly what they should offer, but they do not want to lose the property, so they offer a bit more. Or they tell themselves they can save a bit on the works. Or they decide the contingency is probably being too cautious. Or they quietly reduce the amount of profit they originally said they needed.
Individually, each of those decisions may not look like a disaster.
Collectively, they can leave you in a very exposed position before the work has even begun.
Because on a refurb it does not take much for the margin to start shrinking.
A few extra costs here.
A delay there.
Something else you had not originally allowed for.
Before long, what looked like a decent profit can start looking distinctly average. Or worse.
That is why I have always felt it is better to be a bit conservative at the buying stage than to be enthusiastic and optimistic and then hope for the best.
If the numbers still work with realistic figures, a proper contingency and a profit built in from the outset, then you may well have something worth pursuing.
If they only work because you have been kind to yourself in every assumption, you probably have not.
Sometimes the best decision is not to buy.
That can feel frustrating, especially when you have spent time viewing a property, thinking it through, maybe even getting quotes, and you can see all sorts of possibilities in it. But that is still far better than doing months of work, taking all the risk, and discovering at the end that the margin was never really there.
A refurbishment project should not need wishful thinking to make it profitable.
The profit has to be built in at the beginning.
Not hoped for at the end.
Get that right and you give yourself a much better chance.
Get it wrong and you may only discover the truth when it is too late to do much about it.
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-2/