If there was no contract then you cannot be in breach of it... but then neither can he.
As already mentioned it will help everyone if you show us the original list of work that was agreed. You need to know what the builders price actually covers first and foremost. You do not seem to be very clear on this so far.
Then we will be able to see where something was not included, and thus a necessary addition to the price. If something was clearly not included, but was needed then it is legitimate for him to ask to be paid for this, whether originally quoted for or not, because you would have needed this in any case.
The same happens if you ask him to make a change whilst he is busy working.... for instance, if you decide you want a light switch in a different spot or if you decide that you want to add an extra rooflight. Now, if you can prove he made a mistake and put something in the wrong spot then the cost lies with the builder - but as it sounds like you have no drawings then it sounds like you do not have this proof.
It sounds like this project has been a victim of severe lack of paperwork. He says that you have asked for additional items, but it is likely that if this occurred, then this happened through conversations on site and not through written instruction. If this is true then it means he has no proof that you ever authorised additional work, and so he completed it of his own accord.
You need to be clear though, that just because you supply a builder with some materials that is not to say that the work costs you nothing extra. You need to be aware that builders charge you for the time it takes to carry out the work. So, for example, just because you may have provided blocks to make a wall, there would still be a charge on that wall. He still has to make it - and provide all ancillary components that you may not have provided - such as mortar, plasterboard, adhesives, tapes etc.
Anyway, the point still stands, show us your paperwork.
As already mentioned it will help everyone if you show us the original list of work that was agreed. You need to know what the builders price actually covers first and foremost. You do not seem to be very clear on this so far.
Then we will be able to see where something was not included, and thus a necessary addition to the price. If something was clearly not included, but was needed then it is legitimate for him to ask to be paid for this, whether originally quoted for or not, because you would have needed this in any case.
The same happens if you ask him to make a change whilst he is busy working.... for instance, if you decide you want a light switch in a different spot or if you decide that you want to add an extra rooflight. Now, if you can prove he made a mistake and put something in the wrong spot then the cost lies with the builder - but as it sounds like you have no drawings then it sounds like you do not have this proof.
It sounds like this project has been a victim of severe lack of paperwork. He says that you have asked for additional items, but it is likely that if this occurred, then this happened through conversations on site and not through written instruction. If this is true then it means he has no proof that you ever authorised additional work, and so he completed it of his own accord.
You need to be clear though, that just because you supply a builder with some materials that is not to say that the work costs you nothing extra. You need to be aware that builders charge you for the time it takes to carry out the work. So, for example, just because you may have provided blocks to make a wall, there would still be a charge on that wall. He still has to make it - and provide all ancillary components that you may not have provided - such as mortar, plasterboard, adhesives, tapes etc.
Anyway, the point still stands, show us your paperwork.