I’m saying that at the very least, you did the work in your entitled to be paid for the labour and the materials because, after all, why would you give those for free? That’s the very least you could expect if the court didn’t accept that you did it because you had been promised a chunk of the equity of the property.
Whether the court accepted that you had been offered a chunk of the investment would come down to how persuasive the arguments were for or against.
With regard to the value of the claim, I would do a mathematical calculation of the value of the work that you put in compared to the increase in value of the property, taking into account the original purchase price.
If you can prove that you have a financial interest in the property which he hadn’t paid, then the percentage of the financial interest with the same percentage interest in the rental.
Remember that if this goes to court and you lose for any reason or he makes a Part 36 offer of £35,000 and the court doesn’t offer you more than £35,000, you will have to pay the court costs and his solicitors costs from the date of the offer.
You can issue the claim online but because of the amount being disputed being over £10,000, would not be Small Claims Court and hence there is always a costs risk.
You have to consider whether you are better accepting the £35,000 rather than arguing over £50,000.