It's probably easier to handle as civil negligence. Criminal damage has an intent component. Of course it would hinge on discovery - as soon as you find an email to the effect of "we know this will cause damage, let's test it on someone else's house", that counts as intent.

They intended to defraud this home owner engaged under contract for their own profit. This wasn't unforeseeable or accidental damage nor due to a misunderstanding on their part.

It's also not a dichotomy. It can be both criminal and civil. Victims always have the right to seek compensation in parallel with criminal punishment.