Do I have to pay the contractor's invoice if the work is not done properly?

Questioner

I hired a contractor to install a shed. He said he would take about 48 hours to do it. He did, but the work is not finished yet and what he did is not neat (posts not level, doors are hanging crooked, doors are not the size I specified and the finishing strips are not waterproof, etc.). I paid him half of the hours he worked, and the full amount of the materials he ordered because he asked for it, even though he never wants to give me the invoices for these (he promises to do so, it even says on his invoice that he gave them, but he keeps postponing it). He didn't tell me that the doors were not the right size, which I paid for in good faith without seeing the receipts. I later found out myself that the doors were too narrow, because the engine wouldn't fit through them. He said that the wider doors had a longer delivery time so he ordered them. He has admitted that the doors are not right, they are not level (the posts are not level), and also that the locks will not lock properly because he has placed the doors too far forward of the posts. He has promised to fix this. There is no date yet for the repairs, nor has he ordered replacement doors, posts and slats. Now he asks me if I want to pay the rest of the invoice in full because he has already worked these hours, and that it does not matter that the job is not finished yet. I have told him that I would like him to repair everything first (and order the right doors and materials himself, he wanted me to do this...) before I pay the other half of the invoice. And also that I want to see the receipts for all the materials ordered by him. There is still an amount of € 1150.00 outstanding. I have already paid € 3500.00 in materials and € 1150.00 in labor. Am I within my rights, what is the best way to approach this?

Lawyer

If the contractor has not performed properly, you can in principle suspend your payment obligations. It is wise to record this in a registered letter. You should then state that you will not pay again until the agreed work has been carried out correctly and you should give the contractor a reasonable period for this. Whether the contractor has not performed properly also depends on what you agreed in the construction contract. Is anything recorded about that, for example (?). If there is no proper recording of the agreements made, discussion could of course arise about whether or not performance was performed properly.