Defending a claim or counterclaiming?

[Dandelion9]

A builder has taken out a claim against me as I have not paid his bill due to damage to our property (which he is denying.) Do I need to make a counterclaim in order to legally be able to withhold payment? I thought that I could merely defend not paying in response to his claim (without making a claim myself). Is that okay? I'm not paying him because he didn't do what we agreed, didn't take reasonable skill and knowledge, didn't advise of any risks to our property of doing the work (so that we could make an informed decision of using his services or not), and did deliberate damage.

[atticus]

put to one said the question of his claim against you. Do you have a claim against him? What has been the effect of the "deliberate damage", and what has it cost to put right?

[Dandelion9]

The builder has done damage to huge sections of lime plastering on victorian walls. Lime plastering is prohibitively expensive to replicate. The cost of doing this would far exceed his £4k claim and we would not be able to afford it ourselves. We've had to re plaster with modern methods (including reinforcement mesh to fix the damage) and all of the damage has cost about £2.5k (although we are very upset not to have the original Victorian lime plastering any more). It would have taken too long to see if we would be successful in a claim against him to reinstall the lime plastering as our house would have been in unliveable disrepair for months. At one point, he wanted to return to assess the job again himself. He then proceeded to remove the ceiling coving of a whole room without having any reason to do so and no permission. We have had to pay to have this reinstalled.

[atticus]

You appear to have a counterclaim.