Does anybody know if I am legally required to permit my landlord entry for strictly unnecessary renovations?
I think it depends on the contract you and the landlord have.
I assume the Landlord is an old retired fat lady?

Old fat man who works for the government as one of those "herp derp I read forms while eating cake, drinking coffee and talking shit at the tax payers' expense" type of people. Nice and friendly man, but I don't want any of that.
The contract doesn't specifically mention anything about arbitrary renovations that aren't necessary (such as pipe burst).