does the cooker hob need a extractor fan?

An extractor hood is not a requirement, However it is a good way of eliminating smoke and steam when the hob is in use therefore reducing other problems in the future. Steam in particular obviously creates a very damp environment which over time can reduce the lifespan of kitchen units and worktops. Extractors can be purchaced very cheap now and even a very basic one will help. I would also mention that only an extractor can be fitted above a hob, No units or shelfs should ever be fitted in this space. Hope this helps you decide.

Yes your kitchen designer is correct, you don't have to have one but it's better too have one The main reason for installing an extractor is to take away the smells and grease that are produced during cooking, clean the air....DWPCutler bids his own answers up, because no one else agrees...

Have to agree with Rebel carpenter.His last sentence is bang on.Maybe the tradesman in question should call himself "ZOOLANDER" as he "likes" himself so much lol.

While its not a requirement, at the same time it is good practice to install a cookerhood. I have had several customers insist on not wanting the hood,usually because they have an extractor elsewhere in the room. At the end of the day its the customers kitchen and we can only advise on best practice. Most designs will put one above the hob as its another item that can be sold to the customer.